Article

Prospective Evaluation of Visual Acuity Assessment: A Comparison of Snellen Versus ETDRS Charts in Clinical Practice (An AOS Thesis)

December 2009
Transactions of the American Ophthalmological Society 107:311-24

Source
PubMed

Authors:

THE PURPOSE OF THIS STUDY WAS TWOFOLD: first, to prospectively compare visual acuity (VA) scores obtained with Snellen charts versus Early Treatment Diabetic Retinopathy Study (ETDRS) charts in a "real world" retinal practice, and second, to see if there was a difference in visual acuity measurements obtained with ETDRS charts starting at 4 or 2 meters. Prospective, consecutive evaluation of patients who underwent best-corrected visual acuity testing of their right eye performed at a single seating by the same experienced, certified vision examiner in the same room with standardized low light conditions using a projected Snellen chart at 20 feet, and two different back-illuminated ETDRS charts placed 4 and 2 meters from the patient. One hundred sixty-three eyes were included in the study. The mean Snellen VA was 0.67 logMAR (20/94), ETDRS VA at 4 meters was 0.54 logMAR (~20/69), and ETDRS VA at 2 meters was 0.51 logMAR (~20/65). The mean difference was 6.5 letters better on the ETDRS chart (P=.000000001). As the VA worsened, there was increased variability between the charts and the mean discrepancy between charts also increased. Subgroup analysis revealed the greatest difference between charts was in the poor vision subgroup (<20/200) with a difference of 0.2 logMAR (10 letters; P=.0000002). Patients with exudative age-related macular degeneration (AMD) had the greatest disparity on vision testing, but patients with dry AMD and diabetic retinopathy also exhibited significant differences. Visual acuity scores were significantly better on ETDRS charts compared to Snellen charts. The difference was greatest with poor visual acuity (<20/200) and in patients with exudative AMD. Thus, caution should be exercised when comparing data using the different charts.

Remote web-based self-assessment of visual acuity versus ETDRS in patients with macular diseases: a method comparison study

Article

Full-text available

Mar 2025

Background Macular diseases (MD) lead to frequent clinic visits, involve time-consuming visual acuity (VA) measurements by professionals. Independent home measurements could improve efficiency. This study evaluates the agreement of a web-based test in MD compared to in-hospital measurements. Methods Adults with MD were included at the University Medical Center Utrecht in March-July 2023. Users need a phone, computer, and 3m distance. The test uses Tumbling-E and triangles as optotypes. Primary outcome is the web-based vs. ETDRS Distance Visual Acuity (DVA). Secondary outcomes were test-retest variability (TRV), near visual acuity (NVA), and the Amsler grid. Outcomes were reported in mean differences and 95% Limits of Agreement (LoA). Results 89 eyes were included. The DVA mean difference was 0.03LogMAR(1.5 letters), SD0.17, LoA − 0.31;0.36LogMAR(-15.5;18 letters), TRV had a mean difference of 0.03(1.5 letters) SD0.14. The NVA mean difference was 0.13(6.5 letter) SD0.24, positive- and negative predictive values 0.93(95%CI = 0.82;0.98) and 0.71(95%CI = 0.51;0.86) respectively. Conclusions The agreement of the DVA web-based test is on par with Snellen line assessment and subpar to ETDRS. We showed that elderly can perform this test independently at home, providing a time- and cost-saving opportunity. Developments should focus on the NVA since it can be a valuable adjunct to MD follow-up. Trial registration the Dutch Medical Ethical committee (Medisch Ethische Toetsingscommissie; METC NedMec) registration number: 22–879/DB. Approved at 27-09-2022.

Exploring visual functionality in school-going children (6-12 years) from urban and rural district of Pune

Article

Full-text available

Dec 2024

This study examines visual impairments prevalence in Pune District's urban and rural school children, recognizing environmental influences on visual development. Understanding variations in visual metrics informs public health initiatives. Visual acuity and color vision play pivotal roles in academic and social development, highlighting the importance of targeted vision care strategies. This study emphasizes the importance of early detection and intervention for visual impairments in children, emphasizing the crucial role of clinical optometrists in conducting regular eye check-ups and collaborating with schools and parents. "To compare visual functionality, in school-going children aged 6-12 years from urban and rural districts of Pune, aiming to identify potential disparities." A cross-sectional study in Pune District evaluated 900 systematically selected school children (450 from urban, 450 from rural areas). Visual metrics were assessed: stereo acuity (Titmus test), amplitude of accommodation (RAF rule), refractive status (full spectacle correction), visual acuity (Snellen's chart), and color vision (Ishihara test). Statistical analysis employed descriptive statistics and chi-square tests. In a demographic study of 900 participants from 7 Taluka schools in Pune, Maval Taluka had the highest representation (17.9%). Prevalence of myopia was higher in urban (94.8%) than rural (70.7%) areas, while hypermetropia was more common in rural (29.3%) than urban (5.2%) areas. Color vision deficiencies exhibited no significant difference. Stereo acuity and amplitude of accommodation varied significantly geographically, with stereoacuity notably lower than refractive errors and amplitude of accommodation. The study found lower stereoacuity than refractive errors and amplitude of accommodation, with significant differences between urban and rural children, suggesting environmental influences.

Landolt C-Tests With "Fixed" Arcmin Separations Detect Amblyopia But Underestimate Crowding in Moderate-to-Severe Amblyopic Children and Adults

Article

Full-text available

Aug 2024

Purpose: Crowding is exaggerated in central vision of strabismic amblyopia, impacting on reading ability. Crowding magnitude and interocular differences (IODs) in acuity are indicators for detection, assessment, and monitoring of treatment. Lateral masking (including contour interaction) also affects acuity and can mimic or ameliorate crowding. We investigated lateral masking/contour interaction and crowding impact on crowding magnitude and IOD measures in healthy and amblyopic pediatric and juvenile/adult groups using two Landolt C-tests with "fixed" arcmin separations. Methods: Acuity (logMAR) was measured with Landolt C-tests with specified 2.6' ("crowded") and 35' ("uncrowded") separations. Crowding magnitudes (crowded - uncrowded acuities) and IODs were calculated. Participants were 69 subjects with strabismic amblyopia (n = 39 pediatric, i.e. children ≤8 years of age), 31 subjects with anisometropic amblyopia (n = 14 pediatric), and 76 healthy controls (n = 36 pediatric). Subjects with amblyopia were subgrouped by acuity as low severity (<0.4 logMAR) or high severity (≥0.4 logMAR) using the 35' separation C-test. Results: Crowding magnitudes were greater in strabismic than in anisometropic amblyopia and control/fellow eyes. They were higher in pediatric control/fellow eyes than in juvenile/adult eyes. In high severity strabismic amblyopia, crowding magnitudes progressively and significantly reduced (slope = -0.17 ± 0.07, P < 0.05) with worsening acuity. IODs for this group were higher on the 2.6' C-test, but lower than expected. In high severity pediatric subjects with anisometropic amblyopia, seven of eight had lower IODs measured with the "crowded" than the "uncrowded" C-tests. Conclusions: These C-tests detect amblyopia but underestimate crowding in children and adults with high severity strabismic amblyopia. Separate isolated optotype acuity and crowding distance tests may better target specific functions, while minimizing the impact of masking.

Visual‐somatosensory integration as a novel behavioral marker of amyloid pathology

Article

Full-text available

Mar 2025
ALZHEIMERS DEMENT

INTRODUCTION The ability to integrate information across sensory modalities is a vital aspect of everyday functioning and is linked to cognition. Increasing evidence suggests that Alzheimer's disease (AD) pathology manifests in sensory association areas before appearing in higher‐order cognitive areas. We examined the role of visual‐somatosensory integration (VSI) as a novel behavioral marker of AD‐associated amyloid pathology. METHODS This cross‐sectional study included 243 adults (77 ± 6.5 years; 52% female) who completed the VSI test and AD biomarker assays. The magnitude of VSI was the independent variable and amyloid‐beta probability scores (APS; PrecivityADTM) were the dependent variable. Cognitive status (normal, mild cognitive impairment, or AD) was assigned during case conferences. RESULTS Linear regression revealed an inverse association between the magnitude of VSI and APS (β = −0.16; p ≤ 0.01). As cognitive impairment increased from normal to dementia, the magnitude of VSI decreased (p < 0.05). DISCUSSION Findings provide support for VSI impairment as a new behavioral marker of AD‐associated amyloid pathology. Highlights Here we provide support for the magnitude of VSI as a novel behavioral marker of AD‐associated amyloid pathology given its significant association with an established, accurate, and reliable biomarker of AD pathology. Adults with normal cognition maintained the highest magnitude of VSI and brain amyloid negative scores. As cognitive impairment increased, the mean magnitude of VSI significantly decreased while amyloid probability scores (APS) increased. In fact, individuals with dementia revealed the lowest magnitude of VSI and the highest APS. Our research continues to emphasize the importance of successful multisensory integration in aging, where the establishment of future novel multisensory‐based interventions aimed at preventing disability and optimizing independence could prove valuable.

Beyond Longer Intervals: Advocating for Regular Treatment of Neovascular AMD

Article

Full-text available

Dec 2024

Personalizing the management of neovascular age-related macular degeneration (nAMD) poses significant challenges for practicing retina specialists and their patients. This commentary addresses some of these complexities, particularly those that arise in the context of an expanding array of intravitreal agents targeting vascular endothelial growth factor (VEGF) and related retinal disease targets. Many of these newer agents approved by the Food and Drug Administration (FDA) for the treatment of nAMD have labeling that indicates that they can provide non-inferior visual outcomes when compared head-to-head with previously available treatments and can be used at significantly extended dosing intervals in some patients. It can be difficult to know if patients should be transitioned to these agents, especially those who are doing well on existing therapies. Although offering extended intervals may be appropriate for some patients with excellent disease control, retina specialists know that undertreatment risks the loss of visual acuity (VA). It can also be challenging for clinicians to interpret the results delivered by clinical trial treatment protocols compared with what is likely to occur in real-world office settings. Many retina specialists use less liberal treatment paradigms than employed in clinical study protocols and consequently many patients experience shorter injection intervals. Since VA is most closely linked to quality of life, it should be prioritized compared with other endpoints. The authors advocate for maintaining consistent treatment schedules dictated by disease control instead of switching therapies even in the presence of small amounts of macular fluid that may occur with longer injection intervals.

Effectiveness of EScoop® lenses on a Select Group of Veterans

Article

Full-text available

Apr 2024

Purpose: The purpose of this study was to perform a retrospective chart review to see if the use of EScoop® lenses improved the referred veterans' contrast acuity and subjective visual discomfort of glare, photophobia, or difficulty with night driving. Methods: We retrospectively reviewed examinations of 23 veterans aged 36 to 91 who chose EScoop ® for their spectacle prescription. The EScoop ® set available in our clinic included two shades, yellow or orange, two center lens thicknesses (LT), 6 or 9 mm, and with or without 4 prism diopters yoked base up (BU) prism. Results: The largest diagnostic group tested was with traumatic brain injury (12 of 23), and they preferred the orange-tinted lens (10 of 12). The orange 9 mm LT with 4 prism diopters BU was the most commonly chosen EScoop® lens overall (5 of 23). Pre and post lens visual acuity testing with Sloan EDTRS LogMAR Low Contrast Chart at 25% contrast was available for 13 of the 23 patients. A small but statistically significant improvement of 0.11 decimal mean acuity (about one-line Snellen) under a low contrast condition was noted while wearing the preferred EScoop ® lenses (Wilcoxon Signed Rank P=0.015). Conclusion: Our retrospective study reviewed visually impaired patients with varied clinical conditions, including traumatic brain injury, age-related macular degeneration, glaucoma, and optic atrophy. Upon informal questioning, the patients reported improvements in glare, photophobia, and night glare symptoms. Objectively, we measured approximately one line of improvement in contrast Snellen acuity, which was statistically significant. Further research is needed to discern the actual effectiveness of this lens.

Effectiveness of EScoop® lenses on a Select Group of Veterans

Article

Full-text available

Apr 2024

Inter-Rater Reliability of EyeSpy Mobile for Pediatric Visual Acuity Assessments by Parent Volunteers

Article

Full-text available

Jan 2024
Clin Ophthalmol

Purpose To assess the inter-rater test reliability of the EyeSpy Mobile visual acuity smartphone algorithm when administered to children by eye professionals and parent volunteers. Patients and Methods Visual acuity test-retest results were analyzed for 106 children assigned to one of three different screenings: (1) An eye technician and pediatric ophthalmologist using their typical visual acuity testing method on a M&S computer; (2) An eye technician and pediatric ophthalmologist using EyeSpy Mobile; (3) An eye technician and parent volunteer using EyeSpy Mobile. Results All three phases demonstrated a strong agreement between the two testers, with mean test-retest equivalency results within 0.05 logMAR (2.5 letters, 90% CI). Whether testing using their typical technique on an M&S computer or using EyeSpy Mobile, eye professionals obtained statistically closer mean test-retest results than parent volunteers by 1 letter, with equivalency results within 0.03 logMAR (1.5 letters, 90% CI). Conversely, the number of retests within 2 vision lines was statistically greater when EyeSpy mobile was used by parents as compared to eye professional’s customary technique on the M&S computer. Conclusion EyeSpy Mobile provides clinically useful visual acuity test-retest results even when used by first-time parent volunteers. Adaptive visual acuity algorithms have the potential to improve reliability, lessen training requirements, and expand the number of vision screening volunteers in community settings.

Comparison of Online Visual Acuity Testing with Dynamic Dyop and Static LogMAR Optotypes in Healthy Non-Presbyopic and Presbyopic Individuals

Article

Full-text available

Apr 2025
Clin Ophthalmol

Introduction Visual acuity (VA) is typically measured using stationary optotypes, though real-world visual experiences involve dynamic targets. The Dyop (dynamic optotype) VA test is a computerized motion perception assessment designed to simulate daily visual experiences. With the rise of telemedicine, this study examined the feasibility and agreement between virtual online VA testing using Dyop compared to standard LogMAR optotypes in non-presbyopic and presbyopic participants. Methods After an initial online Zoom® meeting verifying inclusion criteria and technical feasibility, participants accessed the examiner’s computer using the “Anydesk” application enabling them to view the “Chart 2020” program. Monocular right eye VA was measured three consecutive times using Dyop and LogMAR optotypes in a counter-balanced design. Participants aged 18–39 yrs were considered non-presbyopic, and those 40–60 yrs were considered presbyopic. VA measurements were analyzed using the Mann–Whitney U-test, Spearman correlation coefficients, intraclass correlation coefficients (ICC), and non-parametric Bland-Altman analysis, which examined median differences and limits of agreement (LoA). Results Of the 110 participants, (70% females, mean age: 32.5 ± 13.0, range: 18–60), 73 (66%) were considered non-presbyopic (mean age: 24.1 ± 4.9, range: 18–39), and 37 (34%) were presbyopic (mean age: 49.0 ± 6.4, range: 40–60). The mean VA measured with the Dyop and LogMAR charts for the entire cohort (0.09 and 0.08), for the non-presbyopic (0.09 and 0.07) and the presbyopic (0.10 and 0.09) sub-groups was significantly positively correlated (r = 0.80, p < 0.001, r = 0.82, p < 0.001 and r = 0.72, p < 0.001, respectively), with a small mean difference (−0.01 ± 0.08, −0.02 ± 0.08, −0.01 ± 0.09 log units), for the entire cohort, the non-presbyopic, and the presbyopic, respectively. There were no significant differences between the two tests for the whole cohort (p = 0.80), for group 1 (p = 0.98) and for group 2 (p = 0.62). Conclusion This study demonstrated the feasibility of online VA measurements and that online VA measurements using Dyop and LogMAR optotypes are interchangeable in healthy non-presbyopic and presbyopic participants.

Two-Year Switzerland Cohort Results from a Global Observational Study Investigating Proactive Dosing with Intravitreal Aflibercept 2 mg in Neovascular Age-Related Macular Degeneration

Article

Full-text available

Mar 2025

Background/Objectives: XTEND is the largest global, prospective, observational study of treatment-naïve patients with neovascular age-related macular degeneration (nAMD) receiving 2 mg of intravitreal aflibercept (IVT-AFL) in routine clinical practice designed to examine the real-world effectiveness of IVT-AFL proactive treatment regimens. The outcomes from the Switzerland cohort are reported here. Methods: Patients aged ≥50 years were eligible if they planned to receive IVT-AFL 2 mg. After three initial monthly IVT-AFL injections, treatment intervals could be extended (4-week minimum treatment interval). Visual and anatomic outcomes, treatment exposure, and safety were assessed. Statistics were descriptive. Results: Fifty-one patients were treated. At baseline, the mean ± standard deviation (SD) best-corrected visual acuity (BCVA) was 64.9 ± 17.9 letters, and central subfield thickness (CST) was 402 ± 106 µm. At month (M) 12 and M24, the mean (95% confidence interval [CI]) change from baseline in BCVA was +5.7 (1.9, 9.4) and +5.6 (1.3, 9.8) letters, respectively. In patients with a high baseline BCVA (≥70 letters [n = 28; mean ± SD: 77.5 ± 4.8 letters]), BCVA was maintained at ≥70 letters at M12 and M24 (mean change from baseline [range] +1.0 [−15.0, 11.0] and +1.1 [–10.0, 14.0], respectively). At M12 and M24, the mean (95% CI) change in CST was −125 (−161, −90) µm and −127 (−162, −93) µm, respectively. Patients received a mean ± SD of 9.5 ± 3.2 and 13.7 ± 6.0 injections by M12 and M24, respectively. No safety concerns were identified. Conclusions: In Swiss routine clinical practice, functional and anatomic improvements were achieved with IVT-AFL 2 mg proactive treatment in patients with nAMD over 24 months despite a relatively high baseline BCVA.

Obstacle Circumvention Strategies During Omnidirectional Treadmill Walking in Virtual Reality

Article

Full-text available

Mar 2025
SENSORS-BASEL

Obstacle circumvention is an important task for community ambulation that is challenging to replicate in research and clinical environments. Omnidirectional treadmills combined with virtual reality (ODT-VR) offer a promising solution, allowing users to change walking direction and speed while walking in large, simulated environments. However, the extent to which such a setup yields circumvention strategies representative of overground walking in the real world (OVG-RW) remains to be determined. This study examined obstacle circumvention strategies in ODT-VR versus OVG-RW and measured how they changed with practice. Fifteen healthy young individuals walked while avoiding an interferer, performing four consecutive blocks of trials per condition. Distance at onset trajectory deviation, minimum distance from the interferer, and walking speed were compared across conditions and blocks. In ODT-VR, larger clearances and slower walking speeds were observed. In contrast, onset distances and proportions of right-side circumvention were similar between conditions. Walking speed increased from the first to the second block exclusively. Results suggest the use of a cautious locomotor behavior while using the ODT-VR setup, with some key features of circumvention strategies being preserved. Although ODT-VR setups offer exciting prospects for research and clinical applications, consideration should be given to the generalizability of findings to the real world.

Real world data on digital remote refraction in a healthy population of 14,680 eyes

Article

Full-text available

Feb 2025

Refractive errors are the leading cause of preventable visual impairment, to which web-based remote refraction could contribute. We report real-world 2021–2022 data of the underlying algorithm and validated these to conventional prescriptions among healthy individuals (high visual acuity and satisfactied current refraction). Participants were 18–45 years with a spherical (S) error between −3.50 + 2.00S to −2.00 Diopter Cylinder (DC), reported as Spherical Equivalent (SEQ) in mean differences and 95% Limits of agreement. Consecutive measurements ( n = 14,680) were assessed of which n = 6386 selected for validation. The mean difference was 0.01D(SD 0.69) and −0.73D(SD 0.92) for myopes and hyperopes respectively. This algorithm shows variation, nonetheless, 67% and 82% of myopes were within ±0.5 and ±0.75D. The test underestimates hyperopes (34% and 50% within ±0.5D and ±0.75D) and had inconsistencies distinguishing hyperopia. This proof-of-concept shows home testing has the potency to increase accessibility to care by delivering a valuable alternative for uncomplicated refractive assessments.

A study on the prevalence of corneal blindness: A demographic correlates

Article

Jul 2018

Dr Gyan Chandra Dube

Objective: To describe the prevalence corneal blindness and to correlate with demographic profile. Methods: This was a retrospective cross-sectional study. Patients who came in OPD of the Department during the study period were included in the study. Their demographic profile was recorded. Corneal blindness was defined as presenting a VA of less than 3/60 due to corneal disease in the affected eye. The diagnosis was made by the experts available in the OPD. A total of 756 patients of either age and gender with 791 eyes were included in the study. The analysis was based on patients not on number of eyes. Results: The prevalence of corneal blindness in at least one was found to be in 11 patients (1.5%, 95%CI=1.0-3%) in 15 eyes. The prevalence of corneal blindness was lower among males (1.3%) than females (1.7%). The highest prevalence of corneal blindness was noted among the patients of age >50 years (3.4%) and lowest was among the age group <10 years (06%). The prevalence of corneal blindness was higher among the patients of having primary education. The prevalence of corneal blindness was higher among patients belonging to urban area (2%) than rural (1%). The prevalence of corneal blindness was highest among farmers. There was no significant (p>0.05) association of the prevalence of corneal blindness with demographic factors Conclusion: There is a significant burden of corneal blindness in the studied population.Preventive measures for corneal blindness are required for further strengthened.

Effects of lifestyle activity level on anticipatory locomotor adjustments for pedestrian circumvention: an exploratory study

Article

Full-text available

Jan 2025
EXP BRAIN RES

Navigating public environments requires adjustments to one’s walking patterns to avoid stationary and moving obstacles. It is known that physical inactivity induces alterations in motor capacities, but the impact of inactivity on anticipatory locomotor adjustments (ALA) has not been studied. The purpose of the present exploratory study was to compare ALAs and related muscle co-contraction during a pedestrian circumvention task between active (AA) and inactive young adults (IA). Fourteen AA and fourteen IA were placed in a virtual environment simulating a public park. Participants circumvented virtual pedestrians walking towards them. Walking speed, onset of deviation, clearance, foot placement strategies and muscle co-contraction were analysed on a total of 26 participants (13 in each group; 2 excluded due to technical issues). IA exhibited slower walking speeds compared to the AA during circumvention condition but not during unobstructed walking condition. The distance at the onset of trajectory deviation was larger for IA. Both groups increased co-contraction for pedestrian circumvention at the ankle and left hip and IA displayed greater ankle co-contraction overall. No significant group differences were observed in minimum clearance. This study suggests that an inactive lifestyle influences ALAs by inducing a cautious behavior during pedestrian circumvention.

Clinical, laboratory, and orbital imaging features of giant cell arteritis in comparison to non-arteritic anterior ischemic optic neuropath: a single center case series

Article

Full-text available

Dec 2024

Background Giant cell arteritis (GCA) is the most common vasculitis in patients older than 50 years and is considered a “do not miss” diagnosis. However, it remains a diagnostic challenge given overlapping clinical syndromes such as non-arteritic anterior ischemic optic neuropathy (NAION) and poorly explored imaging findings. Materials and methods In this retrospective study between the time period of January 2013 and December 2021, a total of 13 consecutive patients with a pathological diagnosis of GCA and 8 patients with clinical diagnosis of NAION were isolated. Demographic and clinical data for each patient were collected, including pertinent laboratory data. Pertinent physical exam data was also collected, including fundoscopic exam and visual acuity. Two neuroradiologist assessed the orbital MRI imaging findings of GCA and NAION for the presence and characterization of imaging abnormalities. Assessment for potential relationship between GCA orbital findings, laboratory and visual outcomes was performed. Finally, comparison between GCA and NAION imaging findings was performed. Results 13 GCA patients were assessed. 9 patients had abnormal orbital findings. Of these 8 patients had bilateral orbital involvement The most common imaging findings was perineuritis of the optic nerve sheath, present in 7 patients. In total, 8 NAION patients were assessed. All patients demonstrate optic nerve involvement. The Snellen test was converted to logmar, and visual acuity was assessed for both NAION and GCA for each eye at diagnosis and at the last follow-up. There was no statistical significance for either eye for both GCA and NAION at initial diagnosis and final follow-up. In the 4 GCA patients with normal MRI findings and 9 GCA patients with abnormal MRI findings, there was no statistical significance between initial presentation and final follow-up visual acuity. Conclusion GCA and NAION are potentially overlapping clinical syndromes with different treatment approach and poorly explored imaging findings. Our case series assesses the orbital imaging findings of both syndromes while noting different imaging pattern of both on MRI, which can serve as a potential tool to aid in diagnosis of both.

Economic evaluation of an adjunctive intraocular and peri-ocular steroid vitreoretinal surgery for open globe trauma: Cost-effectiveness of the ASCOT randomised controlled trial

Article

Full-text available

Dec 2024
PLOS ONE

Background In the United Kingdom, it is estimated that 5,000 patients sustain eye injuries or ocular trauma requiring hospital admission annually, of which 250 patients will be permanently blinded. This study explores the cost-effectiveness of Adjunctive Steroid Combination in Ocular Trauma (ASCOT) given during surgery versus standard treatment in vitreoretinal surgery in patients with open globe trauma. Methods This economic evaluation was embedded alongside the ASCOT RCT (ClinicalTrials.gov Identifier: NCT02873026). We conducted a primary cost-effectiveness analysis from a National Health Service perspective using the proportion of patients who achieved a visual acuity of 10 or more letter improvement on the Early Treatment Diabetic Retinopathy Study (ETDRS) scale as the measure of effect, in developing incremental cost-effectiveness ratios (ICERs). Secondary cost-utility analysis using the EuroQol 5 Dimension 5 Level (EQ-5D-5L) to generate a cost per quality-adjusted life-year (QALY), and a cost-effectiveness analysis using vision-specific quality of life (QoL) was conducted. Sensitivity analyses were also applied to investigate parameter uncertainties. Results The sample size of the ASCOT intervention arm and standard care arm of this study was 130 and 129, respectively. The intervention cost per patient was estimated at £132. The proportion of participants with an ETDRS of 10 or more letter improvement was 0.47 for the ASCOT group with a mean cost of £5,526 per patient, while the standard care group had an effect of 0.43 with a mean cost of £5,099 per patient. The ICER value of the primary outcome was £12,178 per 10 or more letter improvement on the ETDRS score. The secondary result in terms of cost per QALYs gained had a probability of 44% being cost-effective at a willingness-to-pay threshold of £30,000/QALY gained. Conclusions Though there is no formally accepted cost-effectiveness willingness-to-pay threshold for 10-letter or more improvement, the ASCOT intervention for open globe trauma is a low-cost intervention. The ASCOT intervention is not cost-effective when compared to the standard care in this group and setting. The proportion of patients in the ASCOT intervention arm with 10 or more letter improvement produced some positive results but this is outweighed by the costs.

Monovision versus multifocality for presbyopia during primary phacoemulsification: systematic review and network meta-analysis

Article

Nov 2024

This systematic review and network meta-analysis (NMA) focuses on comparing monovision and bilateral multifocal lenses (bMFIOL) implantation methods in treating presbyopia, a common age-related condition often seen in post-cataract surgery patients. This review focuses on evaluating the efficacy, user satisfaction and limitations of these two approaches through direct or indirect comparison. A comprehensive search was conducted in Medline, Embase, and Cochrane library, considering studies up to 15 July 2022, with direct or indirect comparisons between any monovision and bMFIOL implantation with bilateral cataract surgery. The study protocol has been published in the International Prospective Register of Systematic Reviews (PROSPERO, CRD42022340257). Thirty-two studies (3082 patients) were included in the NMA for the primary outcome, complete post-operative spectacle independence. NMA showed monovision to be inferior to bMFIOLs, as bMFIOL was more likely to provide complete spectacle independence (RR = 2.06, 95% CI = 1.34 to 3.15, p = 0.002) compared to monovision. Monovision resulted in less glare compared to bMFIOL (RR = 0.343, 95% CI = 0.181 to 0.651, p = 0.001). There was no statistically significant difference between monovision and bMFIOL for binocular unadjusted distance visual acuity (MD = 70.01, 95% CI = -19.88 to 4.60, p = 0.437) and binocular unadjusted near visual acuity (MD = 5.46, 95% CI = -5.24 to 10.94, p = 0.191). When compared to monovision, bMFIOL provided greater complete spectacle independence at the expense of greater glare. This study was limited by data heterogeneity, and further studies with standardized reporting would be useful.

Article

Full-text available

Aug 2024

Background Neovascular age-related macular degeneration (nAMD) is a common cause of visual impairment and blindness in the elderly with globally increasing prevalence. Vascular endothelial growth factor inhibitor (anti-VEGF) treatment has improved visual prognosis of nAMD, but continuous treatment may cause anxiety and stress, although increase in visual acuity (VA) may also have positive effects on patients’ quality of life. The health care burden due to frequent treatment and monitoring is apparent, but the effect of anti-VEGF treatment on patients’ quality of life is not fully understood. We evaluated the overall impact of nAMD and its treatment on newly diagnosed patients’ health-related quality of life (HRQoL) in real-world setting. Methods The present prospective cohort study included newly diagnosed nAMD patients treated with anti-VEGF injections at Oulu University Hospital during 2019–2020. Data included parameters from comprehensive ophthalmic examination and fundus imaging, age at diagnosis, sex, comorbidities, visual acuity, and frequency of anti-VEGF injections. HRQoL was assessed by 15D questionnaire at diagnosis, 6 months, and 12 months. Results 95 nAMD patients were included. They were 78 ± 8 years old, 56 (59%) were female, and 74 (78%) had more than one comorbidity. The patients received 8 ± 3 anti-VEGF-injections. Visual acuity (VA) improved from 56 ± 18 to 61 ± 24 Early treatment diabetic retinopathy study (ETDRS) letters in 12 months. VA improved > 5 ETDRS letters in 45 (47%), remained stable in 30 (32%) and decreased > 5 letters in 17 (18%) eyes. The mean total 15D score reflecting overall HRQoL decreased from 0.850 ± 0.104 to 0.834 ± 0.103 in 12 months. Decreased HRQoL was associated with baseline best-corrected VA (BCVA) ≥ 70 ETDRS letters ( p = 0.023) and more than one comorbidity ( p = 0.034). HRQoL regarding visual function increased from 0.765 ± 0.194 to 0.789 ± 0.184 during the 12-month follow-up. Conclusions In real world setting, HRQoL regarding visual function improved in anti-VEGF-treated nAMD patients during the first 12 months after the diagnosis and treatment initiation. Good baseline VA or several comorbidities were associated with decreased overall HRQoL during the follow-up. Despite the effectiveness of anti-VEGF treatment on visual function, several other aspects affecting elderly patients’ everyday life should be considered when nAMD treatment is implemented.

DMEK Surgery at a Tertiary Hospital in Sweden. Results and Complication Risks

Article

Full-text available

Jun 2024
Clin Ophthalmol

Purpose This study reports clinical outcomes up to 6 years after Descemet’s membrane endothelial keratoplasty (DMEK) performed at the Department of Ophthalmology, Örebro University Hospital, Örebro, Sweden. Methods The study has a cross-sectional and case series design. Inclusion criteria were all DMEK-operated eyes during 2013–2018 until repeat keratoplasty. Results Altogether 162 eyes from 120 patients were enrolled. Among eyes without preoperative comorbidities, examined 1–6 years after DMEK, 85.8% achieved visual acuity of 0.1 logMAR or better. The median endothelial cell density (ECD) loss was 27% in a cohort of eyes examined 1–2 years post-DMEK, 31% at 2–3 years, 42% at 3–4 years, and > 60% at 4–6 years post–DMEK. ECD at the examination timepoint was correlated with donor ECD (as expected) and time since surgery. Conclusion The results from DMEK surgeries in Örebro, Sweden, are promising. Further studies with even longer follow–up are needed to evaluate graft sustainability.

Visual perception and user satisfaction in video see-through head-mounted displays: a mixed-methods evaluation

Article

Full-text available

Jun 2024

Objective Our study addresses the challenges limiting the adoption of Extended Reality (XR) Head-Mounted Displays (HMDs), mainly focusing on device quality and cybersickness. We aim to investigate the impact of hardware and software on user experience and task performance while wearing Video See-Through (VST) HMDs. We employ a novel methodology designed to bridge the gaps identified in previous research. Methods This study uses a convergent mixed-methods approach, combining qualitative and quantitative data in a within-subjects evaluation involving 20 participants. This comprehensive evaluation examines visual perception, visual quality, and user experience through a range of tasks. Usability, comfort, and cybersickness are assessed, with insights derived from both user performance metrics and subjective measures collected through in-depth interviews and comments. The study includes three distinct HMDs—two prototypes (PD1 and PD2) and one commercial device (CD1)—to provide a broad analysis of the technology. Findings Our findings reveal that while participants were generally satisfied with VST mode, their preferences varied across devices. CD1 was preferred for its realistic color representation and superior reading task performance due to its high-resolution display and camera. However, visual disturbances and temporal issues differed across devices, with CD1 exhibiting fewer artifacts when stationary but showing more disturbances when participants were moving. Participants found PD1 and PD2 more comfortable for extended use and fewer cybersickness symptoms, but they highlighted color and display resolution issues. These variations underscore the importance of considering both qualitative and quantitative measures in HMD evaluations. Conclusion This mixed-methods evaluation emphasizes the limitations of relying solely on visual perception performance measures for VST HMDs. By integrating both quantitative and qualitative insights, we offer a more detailed evaluation framework to identify design flaws and user experience issues that quantitative metrics alone might miss. This methodology contributes to the field by illustrating how a mixed-methods approach provides a broader perspective on XR technology, guiding future improvements and enhancing VST adoption in future applications.

Exploring the challenges of avoiding collisions with virtual pedestrians using a dual-task paradigm in individuals with chronic moderate to severe traumatic brain injury

Article

Full-text available

May 2024
J NEUROENG REHABIL

Background Individuals with a moderate-to-severe traumatic brain injury (m/sTBI), despite experiencing good locomotor recovery six months post-injury, face challenges in adapting their locomotion to the environment. They also present with altered cognitive functions, which may impact dual-task walking abilities. Whether they present collision avoidance strategies with moving pedestrians that are altered under dual-task conditions, however, remains unclear. This study aimed to compare between individuals with m/sTBI and age-matched control individuals: (1), the locomotor and cognitive costs associated with the concurrent performance of circumventing approaching virtual pedestrians (VRPs) while attending to an auditory-based cognitive task and; (2) gaze behaviour associated with the VRP circumvention task in single and dual-task conditions. Methodology Twelve individuals with m/sTBI (age = 43.3 ± 9.5 yrs; >6 mo. post injury) and 12 healthy controls (CTLs) (age = 41.8 ± 8.3 yrs) were assessed while walking in a virtual subway station viewed in a head-mounted display. They performed a collision avoidance task with VRPs, as well as auditory-based cognitive tasks (pitch discrimination and auditory Stroop), both under single and dual-task conditions. Dual-task cost (DTC) for onset distance of trajectory deviation, minimum distance from the VRP, maximum lateral deviation, walking speed, gaze fixations and cognitive task accuracy were contrasted between groups using generalized estimating equations. Results In contrast to CTLs who showed locomotor DTCs only, individuals with m/sTBI displayed both locomotor and cognitive DTCs. While both groups walked slower under dual-task conditions, only individuals with m/sTBI failed to modify their onset distance of trajectory deviation and maintained smaller minimum distances and smaller maximum lateral deviation compared to single-task walking. Both groups showed shorter gaze fixations on the approaching VRP under dual-task conditions, but this reduction was less pronounced in the individuals with m/sTBI. A reduction in cognitive task accuracy under dual-task conditions was found in the m/sTBI group only. Conclusion Individuals with m/sTBI present altered locomotor and gaze behaviours, as well as altered cognitive performances, when executing a collision avoidance task involving moving pedestrians in dual-task conditions. Potential mechanisms explaining those alterations are discussed. Present findings highlight the compromised complex walking abilities in individuals with m/sTBI who otherwise present a good locomotor recovery.

Unveiling the retinal secrets of neuromyelitis optica spectrum disorder

Article

Full-text available

May 2024

Background Vascular alterations are now recognized as important contributors to the pathophysiology of neuromyelitis optica spectrum disorder (NMOSD). This study aimed to use optical coherence tomography (OCT) and OCT-angiography (OCTA) to assess alterations in the retinal structure and microvasculature in patients with NMOSD, so we can understand pathophysiology of NMOSD, implicating this on disease activity, visual outcome and management on the future. Methods A case–control study was conducted on 40 NMOSD patients with (NMOSD + ON) and without (NMOSD – ON) history of optic neuritis and 36 healthy subjects. The following data were assessed in NMOSD patients: clinical history, EDSS, and visual function testing. Both groups underwent spectral domain (SD)-OCT and OCTA. Results In this study, NMOSD + ON patients had a statistically significant reduction in all SD-OCT parameters compared to healthy control. Regarding OCTA, there was a significant reduction in radial peripapillary capillary density (RPCD) in NMOSD + ON ( P -value < 0.001) and some sectors of NMOSD–ON compared to healthy control. NMOSD + ON patients had significant differences in RPCD compared to those without ( P -value < 0.001). Conclusions Here we show that the advance of this study is that retinal microvascular alterations have been noticed in NMOSD–ON eyes, indicating that subclinical primary retinal vasculopathy and disease activity may occur in NMOSD before onset of ON and retinal atrophy. This may have implications on early detection of disease activity, early interference in management and prognostic tool to visual outcome in following the patients.

Visual acuity screening by school teachers in Far West Nepal: A randomized trial of alternate screening models.

Preprint

Full-text available

May 2024

Background: School vision screening programs are more effective and less costly in comparison to primary eye care model. However, studies have not examined alternate school visual acuity screening methods in Nepal in terms of accuracy and cost. This study was conducted to validate recent evidence from India of the effectiveness and cost of alternate school visual acuity screening models involving all class teachers (ACTs) versus a few selected teachers (STs) from schools in Far West Nepal. Methods: Nine schools in Far West Nepal were randomly selected for the ACTs which is the intervention arm or STs which is the standard arm. Teachers from both arms were trained to identify children aged 6 years and above with visual acuity 6/9 or worse in either eye as well as obvious ocular abnormalities and refer them to an ophthalmic team from Geta Eye Hospital who visited the schools to examine all children regardless of initial screening. Mean values were compared using student t and Wilcoxon rank sum tests, and proportions were compared between study groups using chi square statistics. Results: A total of 3793 children in 5 ACTs schools and 2144 children in 4 STs schools were included. ACTs (80 teachers) screened 3713 children and STs (9 teachers) screened 2064 children aged 6 to 15 years. ACTs had better sensitivity (95.1% [95% CI: 91.9- 98.2]) and specificity (92.8% [95% CI: 92.0%-93.6%]) compared to STs: sensitivity (73.2% [95% CI: 64.4- 82.0]) and specificity (85.3% [95% CI: 83.8-86.7]). More children from ACTs than STs reached the Geta Eye Hospital for further investigation within 3 months (n= 10/30 [33.3%] versus n= 5/18 [27.7%]) for ACTs and STs respectively but the difference was not statistically significant. The cost of screening per child with refractive error and or other ocular abnormalities was

3.05 for ACTs and

5.29 for STs. Conclusion: A school vision screening program involving ACTs in Nepal was more accurate than ST screening in identifying refractive error and or other ocular abnormalities at approximately 60% of the cost.

Three-Year Follow-Up Study Investigating Changes in Retinal Vascular Morphology and the Relationship with Diabetic Retinopathy in Children with Type 1 Diabetes Mellitus

Article

Full-text available

Apr 2024
OPHTHAL RES

Introduction: This study aimed to investigate changes in retinal microvascular morphology and associated factors, and their relationship with diabetic retinopathy (DR) in children with type 1 diabetes mellitus (T1DM). Methods: Thirty-eight children enrolled in this 3-year follow-up study underwent complete ophthalmic examinations including fundus photography. Retinal vascular parameters were measured automatically and compared between baseline and follow-up. Multiple linear regression was used to investigate factors affecting changes in vascular parameters. Binary logistic regression was used to analyze the relationship between retinal microvascular morphology and DR. Results: The caliber of all retinal vessels (within 1–1.5 papillary diameter [PD] from the center of the optic disc, p = 0.030; 1.5–2 PD, p = 0.003), arterioles, and venules (1.5–2 PD, p = 0.001) was narrower in nearly all regions in the follow-up group compared with the baseline group. Vascular tortuosity increased in the central part of the retina and decreased in the periphery. The density (1–1.5 PD, p = 0.030) and fractal dimension (p = 0.037) of retinal vessels were increased at the end of the follow-up compared with baseline. Retinal vascular caliber was independently correlated with DR (odds ratio 0.793 [95% confidence interval 0.633–0.993]; p = 0.044). Conclusion: Retinal microvascular morphology in children with T1DM varied with the disease course. Narrower retinal vessels may be an independent risk factor for DR. Results of this study emphasized the importance of regular follow-up of fundus vascular morphology for the detection of early DR in children with T1DM.

Validation of the Norwegian International Reading Speed Texts (IReST) in adult readers with normal vision

Article

Apr 2024

There is a lack of standardised reading tests in Norwegian suitable for adults and persons with visual impairment (VI). The International Reading Speed Texts (IReST) measure reading performance of longer paragraphs. The aim of this project was to translate and validate the IReST in Norwegian. Each of the German, English and Swedish IReST were translated into Norwegian. The translations were matched for length, linguistic difficulty, and structure, and piloted in five adults. Reading speed was assessed in 25 readers (41 years, SD = 10) with normal vision and the readings were recorded. Reading speeds were analysed for variability between texts and participants. There were no statistically significant differences between the ten texts (135 words, 765 characters [SD=18], word variation index 91.8% [SD = 0.9%]). Reading speed in adult readers was 204 (SD=31) words/min. There was no difference across texts for any of the participants (p>0.05). Reading speed variance was 77.4% between subjects and 22.6% between texts. The Norwegian IReST is standardised and comparable to the international IReST tests. Reading speed falls within normative values in adult readers. The Norwegian IReST will be a valuable tool in assessing reading in clinical health care, rehabilitation and educational practice of adult and visually impaired readers and in reading research.

Comparison of the accuracy of phone applications with Snellen chart in determining visual acuity

Article

Full-text available

Jan 2024

Objective: To correlate the visual acuity assessment as tested by smartphone application with standard Snellen visual acuity. Methodology: A total of 136 individuals were included in this analytical cross-sectional survey conducted at Shifa Foundation Community Health Center, Islamabad between January 2022 and January 2023. Individual’s age ? 18 years were included. Snellen’s visual acuity was assessed using a standard Snellen’s visual acuity chart by the optometrist, while the Paxos checkup by DigiSight technologies was used to assess visual acuity on smart phone using one appropriately color calibrated I-phone 7 device. Both assessments were done in physically separate areas to reduce observation bias. Visual acuity from each assessment was noted in the decimal format. Frequency distribution and Pearson’s correlation was calculated to ascertain the relationship between the two study variables. Results: A total of 88 males and 48 females were included in the study (n=136). The mean age of patients was 29.72±9.0 years. The mean visual acuity of right and left eyes as assessed with Snellen’s chart were 0.88±0.2 and 0.86±0.22, respectively. The mean visual acuity for right and left eyes as assessed by Paxos checkup were 0.84±0.19 and 0.86±0.21, respectively. There was positive correlation was present in both eyes. The Pearson’s correlation for right eyes was r = 0.66 and significant at p = 0.001, while the correlation for left eyes was r = 0.71 and significant at p = 0.001. Conclusions: There is a strong correlation between Snellen’s visual acuity assessment and assessment of visual acuity by the smartphone application. This makes the latter a viable strategy for screening at places where taking a Snellen’s chart might not be feasible.

Visual Function Measurements in Eyes With Diabetic Retinopathy: An Expert Opinion on Available Measures

Article

Full-text available

Apr 2024

Clinical Relevance Visual function impairment from diabetic retinopathy can have a considerable impact on patient’s quality of life. Best-corrected visual acuity (BCVA) is most commonly used to assess visual function and guide clinical trials. However, BCVA is affected late in the disease process, is not affected in early disease, and does not capture some of the visual disturbances described by patients with diabetes. The goal of this report is to evaluate the relationship between diabetic retinal disease (DRD) and visual function parameters to determine which if any of them may be used in a future DRD staging system. Methods The visual functions working group was 1 of 6 areas of DRD studied as part of the DRD staging system update, a project of the Mary Tyler Moore Vision Initiative. The working group identified 12 variables of possible interest, 7 of which were judged to have sufficient preliminary data to suggest an association with DR to warrant further review: microperimetry, static automated perimetry, electroretinogram (ERG) oscillatory potentials, flicker ERG, low luminance visual acuity (LLVA), contrast sensitivity (CS), and BCVA. The objective field analyzer (OFA) was added after subsequent in-person workshops. Results Currently, the only visual function test available for immediate use is BCVA; the remaining tests are either promising (within 5 years) or have potential (>5 years) use. Besides BCVA, most visual function tests had a limited role in current clinical care; however, LLVA, CS, flicker ERG, and OFA demonstrated potential for screening and research purposes. Conclusions Although current visual function tests are promising, future prospective studies involving patients with early and more advanced retinopathy are necessary to determine if these tests can be used clinically or as endpoints for clinical studies. Financial Disclosure(s) Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Morphological and Functional Correlations in Acute Central Serous Chorioretinopathy

Article

Full-text available

Mar 2024
DOC OPHTHALMOL

Purpose We evaluate morphological and functional correlations in patients with acute central serous chorioretinopathy (CSC). Methods A prospective study was conducted on 50 patients with an acute CSC episode lasting less than 3 months. At baseline, assessments included optical coherence tomography (OCT), best-corrected visual acuity (BCVA), contrast sensitivity (CS), microperimetry (MP), and multifocal electroretinography (mfERG). A correlation analysis between OCT morphological parameters (maximal subretinal fluid height (SRF), central retinal thickness (CRT), and macular volume (MV)) and functional parameters was conducted on the affected eye for each patient. Results Among the morphological parameters, SRF showed the strongest correlations with functional parameters (r absolute value range = 0.10–0.70). Weak correlations were observed between BCVA and morphological parameters (r absolute value range = 0.14–0.26). Average retinal sensitivity (MP-A) was the functional parameter displaying the most robust negative correlation with morphological parameters (r absolute value range = 0.61–0.70). In contrast, average contrast sensitivity (CS-A) and mfERG average amplitude density in the first (mfERG-A1) and second (mfERG-A2) ring showed weak to moderate (r absolute value range = 0.35–0.56) yet statistically significantly nonzero correlations. Conclusions SRF and CRT could serve as the most representative morphological proxies for visual function deficit in acute CSC patients. Retinal sensitivity, as measured by MP, may be superior to BCVA in clinical research studies or when an in-depth visual function evaluation is needed.

Exploring the challenges of avoiding collisions with virtual pedestrians using a dual-task paradigm in individuals with chronic moderate to severe traumatic brain injury

Preprint

Full-text available

Mar 2024

Background: Individuals with a moderate-to-severe traumatic brain injury (m/sTBI), despite good locomotor recovery after six months post-injury, face challenges in adapting locomotion to the environment. They also present with altered cognitive functions, which may impact dual-task walking abilities. Whether they present collision avoidance strategies with moving pedestrians that are altered under dual-task conditions, however, remains unclear. This study aimed to compare between individuals with m/sTBI and age-matched control individuals: (1), the locomotor and cognitive costs associated with the concurrent performance of circumventing approaching virtual pedestrians (VRPs) while attending to an auditory-based cognitive task and; (2) gaze behaviours associated with VRP circumvention task between single and dual-task conditions. Methodology: Twelve individuals with m/sTBI (age=43.3±9.5 yrs; >6 mo. post injury) and 12 healthy controls (CTLs) (age=41.8±8.3 yrs) were assessed while walking in a virtual subway station viewed in a head-mounted display. They performed a collision avoidance task with VRPs, as well as auditory-based cognitive tasks (pitch discrimination and auditory Stroop), both under single and dual-task conditions. Dual-task cost (DTC) for onset distance of trajectory deviation, minimum distance from the VRP, maximum lateral deviation, walking speed, gaze fixations and cognitive task accuracy were contrasted between groups using generalized estimating equations. Results: In contrast to CTLs who showed locomotor DTCs only, individuals with m/sTBI displayed both locomotor and cognitive DTCs. While both groups walked slower under dual-task conditions, only individuals with m/sTBI failed to modify their onset distance of trajectory deviation and maintained smaller minimum distances and smaller maximum lateral deviation compared to single-task walking. Both groups showed shorter gaze fixations on the approaching VRP under dual-task conditions, but this reduction was less pronounced in the individuals with m/sTBI. A reduction in cognitive task accuracy under dual-task conditions was found in the m/sTBI group only. Conclusion: Individuals with m/sTBI present altered locomotor and gaze behaviours as well as cognitive performances when executing a collision avoidance task involving moving pedestrians, especially under dual-task conditions. Potential mechanisms explaining those alterations are discussed. Present findings highlight the compromised complex walking abilities in individuals with m/sTBI who otherwise present a good locomotor recovery.

A Quality of Experience Evaluation of Text and 3D Instruction Formats in Augmented Reality Applications

Thesis

Full-text available

Jul 2023

Augmented reality (AR) is an emerging technology that has significant potential as a solution for novel procedure assistance and repeatable procedure training. Instructions are a method to communicate how to perform a procedure for different pedagogical goals ranging from assistance with once-off product assembly to long term learning. The main barrier to mass adoption of see-through AR headsets for these roles arises when AR instruction fails to fulfil the user’s pragmatic and hedonic needs and expectations due to human, system and context influencing factors. User quality of experience (QoE) considers this fulfilment to be reflected in the user’s degree of delight or annoyance. The ability to directly measure emotional response using modern psychophysiological instruments is shifting the focus of quality assessment towards evaluation of fulfilment of user needs and expectations. In this context, the work presented in this thesis focuses on understanding the influence of instruction formats considering AR as a potential platform for procedure assistance and training. Instruction format was evaluated over two distinct studies specific to the procedure assistance and training roles. In Study 1, the influence of paper-based and AR-based text instruction formats on user QoE for procedure assistance was evaluated using a Rubik’s Cube® proof of concept. In Study 2, a combined text and interactive animated 3D model instruction format was compared against a text-only instruction format within AR using a GoCube™ proof of concept for training. Two separate AR applications were developed. Physiological ratings, facial expressions and eye gaze metrics were recorded. Subjective experience was reported using Likert scale, self-assessment manikin and NASA task load questionnaires. Statistical analysis was employed to identify statistically significant differences between usage of the different instruction formats. Correlation and regression analysis were undertaken to identify novel implicit metrics of QoE. Study 1 results show that the AR instruction format yielded objective performance benefits over the paper-based instruction format for procedure assistance while participants reported higher acceptability of AR. Skin temperature correlated to joy of experience and facial expressions across both independent groups. Study 2 results show that the text-only instruction format yielded faster instruction response times in procedure training compared to a combined text and model instruction format. Female trainees using the combined instruction format were significantly slower in training and recall than females that used the text-only instruction format but reported requiring less cognitive effort than male participants during training and recall. An absence of statistically significant correlations between physiological ratings, facial expression and emotion terms used by the participants, calls into question the utility of such emotion terms.

Interleukin-8 Promoter Polymorphism −251 A/T and Treatment Response in Neovascular Age-related Macular Degeneration

Article

Full-text available

Feb 2024
Clin Ophthalmol

Purpose Interleukin-8 (IL-8) is a potent pro-angiogenic and pro-inflammatory chemokine, suggested to hold a role in neovascular age-related macular degeneration (nAMD). Our aim is to study the association of the single-nucleotide polymorphism −251 A/T (rs4073) in the IL-8 promoter region with the treatment response to intravitreal anti-vascular endothelial growth factor (VEGF) injections in nAMD. Patients and Methods This is a prospective study of treatment-naïve patients with nAMD. Treatment response after a loading dose of three intravitreal anti-VEGF injections was defined as functional response based on change in visual acuity, and morphological response based on change in central retinal thickness (CRT) and intraretinal fluid on optical coherence tomography. Morphological response was categorized in good, partial, and poor responders. Blood DNA was analyzed for −251 A/T genotype. Results The IL-8 promoter polymorphism −251 A/T was not significantly associated to functional treatment response (P=0.09). No significant association was found between genotype and morphological treatment response (P=0.799). Older age was significantly associated to good morphological responders compared to partial and poor responders (P=0.014). Conclusion The IL-8 polymorphism −251 A/T is not associated to morphological nor functional treatment response to intravitreal anti-VEGF injections in patients with nAMD.

Visual Acuity Examination Methodology in Keratoconus

Article

Full-text available

Dec 2023

Visual acuity is one of the most important parameters for evaluating the vision of patients with keratoconus. This study reviewed 295 articles related to keratoconus published between 2017 and 2022 in which visual acuity was one of the parameters measured. The methodology of visual acuity testing in studies on keratoconus was thoroughly analyzed. The analysis showed that the most commonly indicated chart for testing visual acuity papers on keratoconus is the Snellen chart. It was shown that in 150 out of 295 articles, the authors do not describe the methodology for testing visual acuity. What is more, it was also shown that in 68 of the 295 articles which were analyzed, a procedure for converting visual acuity tested with a Snellen chart into a logMAR scale was used. In this review, we discuss the validity and reliability of such conversions. In particular, we show that insufficient description of visual acuity testing methodology and lack of information on the conversion of visual acuity results into the logMAR scale may contribute to the misinterpretation of visual acuity test results.

Comparison of smartphone based peek visual acuity with Snellen Visual Acuity

Article

Full-text available

Oct 2023

Purpose: To test an alternative method of visual acuity assessment by comparing habitual and best-corrected visual acuity by Snellen and Peek (a visual acuity testing smartphone application). Methods: A prospective study comparing visual acuity using Snellen's and Peek's visual acuity charts (smartphone-based applications). 162 eyes were assessed in this hospital-based setting by a single observer. Patients with gross ocular pathology and visual acuity less than 6/60 were excluded from the study. Results: There was no statistically significant difference between best corrected visual acuity by Snellens and Peeks'. Snellen's mean best corrected visual acuity was 0.9902 (±0.075), and Peek acuity was 0.9875 (±0.080). Conclusion: The visual acuity assessment by Peek is comparable to that of Snellen's; hence, it can be used as an excellent alternative to Snellens' visual acuity testing.

Determining the variability associated with visual acuity and refractive error measurements: a systematic review

Article

Apr 2025
OPHTHALMOLOGY

A Comparative Study to Validate PEEK Acuity Smartphone Application for Home-based Vision Screening in India

Article

Mar 2025

Background Vision screening via portable eye examination kit (PEEK) acuity app provides results comparable to the gold standard Snellen or early treatment of diabetic retinopathy study (ETDRS) charts when administered by professionals. However, data on the accuracy of vision assessments conducted by laypersons using PEEK acuity is limited. This study evaluates whether visual acuity measurements taken by a layperson using the PEEK acuity app align with those obtained through traditional Snellen chart screening by a trained refractionist mid-level ophthalmic personnel (MLOP). Methods A total of 66 volunteers underwent vision screening of the right eye. Initially, their visual acuity was assessed using the PEEK acuity app by a layperson. This was followed by a second assessment using the Snellen acuity chart, conducted by an MLOP. Results A paired t -test indicated no significant difference between the visual acuity measurements obtained by the two methods and the Pearson correlation coefficient is 0.718 with a P -value < 0.05 suggesting a moderate to strong positive correlation. Conclusion The PEEK acuity app is an effective and cost-efficient tool for home-based vision screening, even when conducted by laypersons. By leveraging smartphone technology, PEEK acuity can facilitate vision screening in the comfort of individuals’ homes, reducing the need for on-site visits and enhancing accessibility, particularly for those in remote or underserved regions. This transition to home-based vision screening would improve early detection and intervention for visual impairments, enabling a more scalable, convenient, and user-friendly approach to public health vision initiatives.

Low Vision Services Are Underutilized by Patients with Vision Loss from Corneal Disease

Article

Mar 2025

Purpose This study evaluated the rate at which patients with visual impairment primarily from corneal disease were referred for low vision (LV) services and assessed the visual outcomes from completed evaluations. Methods This 1-year retrospective, cross-sectional study included patients with corneal disease limiting best-corrected visual acuity (BCVA) to ≤ 20/40. Outcome measures included the change in BCVA achieved after distance refraction by a LV specialist. Incremental costs per quality-adjusted life years (QALY) gained were calculated upon the better-seeing eye, by using a willingness-to-pay threshold of USD 50,000/QALY. Results Of 3230 patients, 143 (4.4%) had visual impairment from corneal disease. The median age of those patients was 80 years (IQR: 66–88 years) and 64.3% were male. Just over half were referred for LV evaluations (53.2%), and most completed appointments (96.1%). Patients more likely to be referred had better vision in their worse-seeing eye (0.961 logMAR vs. 1.451 logMAR, P = 0.002) and were more frequently diagnosed with corneal dystrophies, degenerations, or ectatic disease (51.3% vs. 26.9%, P = 0.003) compared with other corneal conditions, but they were less likely to have immunologic conditions (2.6% vs. 13.4%, P = 0.016). In total, two-thirds of patients achieved improved BCVA for their better-seeing eye, with 32% gaining ≥ 2 lines. This translated into an average gain of 0.04 QALYs/patient at a cost of USD 3128/QALY. The estimated net monetary benefit was USD 1923/LV evaluation completed. Conclusions Referring patients with corneal disease to LV services resulted in significant improvements in visual function at a reasonable cost.

Safety of intravenous thrombolysis in central retinal artery occlusion patients with concomitant acute cerebral infarctions

Article

Feb 2025
J NEUROL SCI

Relationship between Visual Acuity and Intraocular Pressure among Glaucoma Suspected Patients in Gwalior City of Central India

Article

Full-text available

Dec 2024

Background: Rise in intraocular pressure (IOP) is a major risk factor for the development of primary open-angle glaucoma, and even in normal tension glaucoma, the reduction of IOP may slow the progression of visual field loss. The longer the IOP stays elevated, the more the vision is affected. The main objective of this study is to observe relationship between visual acuity and IOP in suspected glaucomatous patients and to find any association of age and gender with the visual acuity. Materials and methods: This observational study was conducted on 100 suspected glaucomatous patients. Visual acuity was recorded using Snellen’s chart and IOP using GAT noncontact tonometry. Chi-squared test and Fisher’s exact test, one-way analysis of variance (ANOVA) were applied using Statistical Package for the Social Sciences (SPSS-22). Statistical significance was assessed on 5% level of significance. Results: In the study, we observed 200 eyes of 100 patients, and it was found that 43 eyes had mild, 96 eyes had moderate, and 17 eyes had severe visual impairment. Visual impairment was found to be significantly associated with age, gender, and IOP. For right eye, the mean IOP showed a significant increase from 15.37 ± 2.91 mm Hg in normal to 23.13 ± 8.04 mm Hg in severe visual impairment. While for left eye, the mean IOP was increased from 16.42 ± 2.94 mm Hg among normal eyes to 17.08 ± 5.16 mm Hg among the severe visual impairment eyes. Conclusion: Present study showed a statistically significant relationship between IOP and vision, that is, as IOP rises there was increase in severity of visual impairment from normal to severe. Hence, controlling IOP is important to prevent visual impairment.

Suprachoroidal Triamcinolone Acetonide for Noninfectious Uveitis: Real-World Impact on Clinical Outcomes

Article

Dec 2024
AM J OPHTHALMOL

Visual Acuity

Chapter

Jan 2024

A Telemedicine-Enabled Intravenous Thrombolytic Treatment Pathway for Patients with Hyperacute Non-Arteritic Central Retinal Artery Occlusion

Article

Oct 2024

Evaluating Online Measures of Contrast Sensitivity and Visual Acuity

Preprint

Full-text available

Sep 2024

Good visual acuity (VA) and contrast sensitivity (CS) are essential for many behaviours (from reading to driving), and tests of visual function have become crucial for many purposes. Clinicians and researchers administer the clinically validated versions of these tests under carefully controlled lighting conditions. However, the rapid expansion of online testing highlights the great utility of having these tests available in digital format. We conducted two experiments to determine whether accurate and reliable online testing of VA and CS is possible. Firstly, participants completed both the Online and Clinical measures of CS and VA in one session and the Online measures in a separate session. Secondly, we artificially degraded vision (using 0.4 logMAR Bangerter filters) in three different visual conditions (full vision, monocular blur and binocular blur) and again compared the Online and clinical tests. The results showed that the Online tests of CS and VA provided a reasonable estimation of CS and VA with little to no bias compared to their clinical equivalent. However, the Online tests were affected by increased noise compared to the clinical tests. The Online tests were sensitive to changing levels of visual blur and were robust to poorly calibrated visual displays. We conclude that our Online measures provide a valid, reliable and robust option for the mass testing of CS and VA.

Evaluating a web-based visual acuity and refractive error self-assessment tool in myopic children

Article

Jul 2024
OPHTHAL PHYSL OPT

Introduction Demands for myopia management are rising. A web‐based tool that allows home‐performed self‐assessments of visual acuity (VA) and refractive error may enable hybrid care pathways and aid in identifying those with deteriorating visual performance. The tool has been validated in adult populations, but has yet to be evaluated in children. This study compared home‐performed VA and refraction self‐assessments to conventional measurements obtained at the clinic in a population of myopic children. Methods Myopic children aged ≥6 years old were invited to perform web‐based eye tests at home, assisted by a parent. At two myopia control clinics, they also underwent measurements of VA using a Snellen chart and refractive error using cycloplegic autorefraction. Agreement between the tests, repeatability of the web‐based test and associations between clinical characteristics and web‐based test accuracy were evaluated. Results A total of 147 children were enrolled, of whom 116 (51% male; mean age 13 ± 3 years; mean spherical equivalent refraction (SEQ) −5.58 ± 3.05) performed the web‐based tests at home. Overall, the home‐performed VA self‐assessment and the Snellen chart assessment at the clinic agreed well (mean difference 0.03 ± 0.11 logMAR). A significant proportional bias was identified (β 0.65, p < 0.001), indicating underestimated web‐based VA scores when the child's vision declined. The sensitivity to detect VA poorer than 0.10 logMAR was 94%; the specificity was 71%. The web‐based refractive error algorithm measured more myopia progression compared to clinic observations (mean difference SEQ 0.40 ± 0.51 dioptres). Age, sex or use of atropine drops were not significantly associated with test accuracy. Conclusions The web‐based test for self‐assessing vision, performed at home by children with assistance from their parents, yielded VA scores with a precision similar to Snellen chart testing conducted in a clinical setting. However, the web‐based refractive error algorithm overestimated myopia progression and requires recalibration for this specific age group.

Vision screening and refraction of Greenlandic schoolchildren

Article

Jul 2024

Purpose: To estimate the prevalence of amblyopia and refractive errors among 6-year-old children in Greenland and to assess the impact of incorporating autorefraction, stereoacuity and near visual acuity testing into vision screening. Methods: In this cross-sectional study, 517 children (238 girls and 279 boys) from 21 locations in Greenland were screened using HOTV charts for distance and near visual acuity (VA), stereoacuity test and non-cycloplegic autorefraction. Referral criteria for further ophthalmological examination included a VA of ≥0.2 logMAR on the worse-seeing eye or an interocular VA difference of ≥2 lines. Results: Initial screening identified amblyopia (defined as VA of ≥0.3 logMAR) in 7% (unilateral) and 3% (bilateral) of children. However, subsequent ophthalmological examinations confirmed amblyopia in under 40% of referrals. Significant interocular VA differences were found in 9%. The prevalence of refractive errors at the screening was 3% for myopia (≤-0.5 dioptres), 10% for hyperopia (>+2.0 dioptres) and 14% for astigmatism (≤-1.00 dioptres), while the corresponding prevalences at the ophthalmological examination were 4% for myopia, 8% for hyperopia and 6% for astigmatism. Combining screening measurements increased the positive predictive values, thereby enhancing screening accuracy. Specifically, the incorporation of autorefraction or stereoacuity with distance VA demonstrated to be the most effective combination. Six percent of the children were prescribed glasses after the screening procedure. Conclusion: This study provides the first visual profile of Greenlandic schoolchildren. Incorporating autorefraction, stereoacuity and near visual acuity in vision screenings enhanced the efficacy of detection of vision anomalies. Although this may lead to more false positives, accurate screening is crucial in regions with limited ophthalmological resources.

Investigating the impact of asymmetric macular sensitivity on visual acuity chart reading in choroideremia

Article

Jul 2024
OPHTHAL PHYSL OPT

Introduction Degeneration in choroideraemia, unlike typical centripetal photoreceptor degenerations, is centred temporal to the fovea. Once the fovea is affected, the nasal visual field (temporal retina) is relatively spared, and the preferred retinal locus shifts temporally. Therefore, when reading left to right, only the right eye reads into a scotoma. We investigate how this unique property affects the ability to read an eye chart. Methods Standard‐ and low‐luminance visual acuity (VA) for right and left eyes were measured with the Early Treatment of Diabetic Retinopathy Study (ETDRS) chart. Letters in each line were labelled by column position. The numbers of letter errors for each position across the whole chart were summed to produce total column error scores for each participant. Macular sensitivity was assessed using microperimetry. Central sensitivity asymmetry was determined by the temporal‐versus‐nasal central macular difference and subsequently correlated to a weighted ETDRS column error score. Healthy volunteers and participants with X‐linked retinitis pigmentosa GTPase regulator associated retinitis pigmentosa ( RPGR ‐RP) were used as controls. Results Thirty‐nine choroideraemia participants (median age 44.9 years [IQR 35.7–53.5]), 23 RPGR ‐RP participants (median age 30.8 years [IQR 26.5–40.5]) and 35 healthy controls (median age 23.8 years [IQR 20.3–29.0]) were examined. In choroideraemia, standard VA in the right eye showed significantly greater ETDRS column errors on the temporal side compared with the nasal side ( p = 0.002). This significantly correlated with greater asymmetry in temporal‐versus‐nasal central macular sensitivity ( p = 0.04). No significant patterns in ETDRS column errors or central macular sensitivity were seen in the choroideraemia left eyes, nor in RPGR ‐RP and control eyes. Conclusion Difficulty in tracking across lines during ETDRS VA testing may cause excess errors independent of true VA. VA assessment with single‐letter optotype systems may be more suitable, particularly for patients with choroideraemia, and potentially other retinal diseases with asymmetric central macular sensitivity or large central scotomas including geographic atrophy.

Prevalence and Impact of Refractive Errors in School-Aged Children: A Cross-Sectional

Article

Jun 2024

This cross-sectional study aims to determine the prevalence and patterns of refractive errors among 700 schoolchildren aged 5-15 years in Al-Manara School, Tobruk, Libya. A comprehensive ophthalmic examination will be conducted to assess visual acuity and identify refractive errors. Academic performance will be evaluated by reviewing school records, including grades and standardized test scores. The impact of refractive errors on quality of life will be measured using a validated pediatric vision-related quality of life questionnaire. The study seeks to provide data on the burden of refractive errors and their effects on learning and daily living in this population. We hypothesize that uncorrected refractive errors will be associated with poorer academic achievement and reduced quality of life compared to peers without vision impairment. This research can highlight the need for regular vision screening and provision of spectacles for schoolchildren in Libya. Findings may guide education policy and school health programs to address this treatable cause of impaired classroom performance. The large sample size will allow for analysis of prevalence stratified by key demographics and characterization of the patterns of refractive errors in this geographic setting.

Self-assessment of Visual Acuity Using a Smartphone Application

Article

Jun 2024

Purpose: We evaluated the accuracy and usefulness of self-assessment of visual acuity (VA) using a smartphone application for Korean users and explored its potential application in screening eye diseases.Methods: In total, 52 participants aged ≥ 20 years were included in the study. Of these participants, 31 used Jin Yong-Han’s VA chart and the smartphone application to measure their distant visual acuity (DVA), whereas 21 used Han Chun-Seok’s near visual acuity chart and the application to measure their near visual acuity (NVA). The results and time required for VA measurement using both methods were compared. VA was converted to logarithm of the minimum angle of resolution (logMAR) for analysis. The voice recognition rate of the application for numbers 2-9 was assessed.Results: The mean NVA was 0.29 ± 0.28 using Han’s chart and 0.30 ± 0.43 using the application with no significant difference ( p = 1.00). The mean DVA was 0.19 ± 5.89 using Jin's chart and 0.20 ± 0.27 using the application with no significant difference ( p = 0.19). The average time spent for measuring NVA and DVA was 19 seconds (s) using Han’s and Jin's charts, whereas it was 42 and 38 s for measuring NVA and DVA using the application. The voice recognition rate of the application was 87% on average for numbers 2-9, with the highest rate for number 7 (79%) and the lowest rate for number 4 (91%).Conclusions: Self-assessment of VA using a smartphone application exhibited similar results to conventional VA measurement methods. Although the measurement time varied, DVA and NVA could be measured at home using a smartphone, and would be particularly useful for those who have difficulty visiting a hospital.

Web-based Telemonitoring of Visual Function and Self-reported Postoperative Outcomes in Cataract Care: an International Multicenter RCT

Article

May 2024
J CATARACT REFR SURG

Purpose Comparing web-based, self-administered follow-up after cataract surgery to conventional face-to-face follow-up. Setting Eye clinics in the Netherlands, Austria and Germany. Design Randomized controlled trial with an embedded method comparison study [ClinicalTrials.gov: NCT04809402]. Methods Routine cataract patients were randomized into two groups: the 'telemonitoring' group undertook web-based vision self-assessments and questionnaires from home, while the 'usual care' group received conventional care. All participants had a 4-6 week post-surgery clinic visit for safety and validation purposes. Outcomes included: the web-test's accuracy for assessing postoperative visual acuity (VA) and refractive error; adverse event rates; and patient reported outcome measurements (PROMs). Results 94 participants (188 eyes) were enrolled. Web-based uncorrected distance VA testing demonstrated a negligible mean difference (-0.03±0.14 logMAR) when compared to conventional ETDRS chart testing, with 95% limits-of-agreement ranging from -0.30 to 0.24 logMAR. The web-based refraction assessment overestimated the postoperative refractive error (mean difference 0.15±0.67 diopters), resulting in a poorer corrected distance VA compared to subjective refraction (mean 0.1 vs. -0.1 logMAR). Rates of adverse events and unscheduled consultations were minimal across both groups. Preoperative and postoperative PROMs questionnaires had a 100% response rate. Visual functioning (Catquest-9SF and NEI-VFQ-25) improved after surgery (mean improvement -0.80 and 16.70 respectively) and did not significantly differ between the two groups. Conclusion The cataract patients in this study effectively provided postoperative outcome data via a web-interface. Both conventional and web-based follow-ups yielded similar PROMs and adverse event rates. Future developments should reduce the variability in the web-based VA test and yield representative refraction outcomes.

Therapeutic benefit of idebenone in patients with Leber hereditary optic neuropathy: The LEROS nonrandomized controlled trial

Article

Feb 2024

Leber hereditary optic neuropathy (LHON) is a mitochondrial disease leading to rapid and severe bilateral vision loss. Idebenone has been shown to be effective in stabilizing and restoring vision in patients treated within 1 year of onset of vision loss. The open-label, international, multicenter, natural history-controlled LEROS study (ClinicalTrials.gov NCT02774005) assesses the efficacy and safety of idebenone treatment (900 mg/day) in patients with LHON up to 5 years after symptom onset (N = 199) and over a treatment period of 24 months, compared to an external natural history control cohort (N = 372), matched by time since symptom onset. LEROS meets its primary endpoint and confirms the long-term efficacy of idebenone in the subacute/dynamic and chronic phases; the treatment effect varies depending on disease phase and the causative mtDNA mutation. The findings of the LEROS study will help guide the clinical management of patients with LHON.

Enhancing Inverted Internal Limiting Membrane Flap Stability in Macular Hole Retinal Detachment by the “Viscoelastic Agent Pool” Technique

Article

Jan 2024
RETINA-J RET VIT DIS

Purpose To evaluate the surgical anatomical and functional results of “viscoelastic agent pool” technique-assisted stability of inverted internal limiting membrane (ILM) flap in macular hole retinal detachment (MHRD). Methods The innovative surgical technique was carried out on 10 patients with MHRD. The primary outcomes included best corrected visual acuity (BCVA) after surgery, rate of closure of MH, retinal reattachment, and occurrence of complications. Results The mean age of the individuals was 67.70±8.75 (range, 55–84) years; mean axial length, 29.34±1.53 (range, 27.10–30.93) mm; mean corrected MH diameter, 685.30± 345.65 (range, 172–1325) μm; and average follow-up period, 6.01±1.71 (range, 3.10–8.4) months. In six eyes (60%), the postoperative BCVA showed improvement. All patients had MH closure, and the retinal reattachment rate was 100%. No postoperative complications were noted. Conclusions The "Viscoelastic agent pool" technique, an innovative surgical approach designed to enhance the stability of the ILM flap, serves as an effective adjunctive procedure for the inverted ILM flap technique. It presents a viable option for patients with MHRD.

Uniformity of Visual Acuity Measures in Published Studies

Article

Full-text available

Nov 2008

To investigate the methods used in contemporary ophthalmic literature to designate visual acuity (VA). Papers in all 2005 editions of five ophthalmic journals were considered. Papers were included if (1) VA, vision, or visual function was mentioned in the abstract and (2) if the study involved age-related macular degeneration, cataract, or refractive surgery. If a paper was selected on the basis of its abstract, the full text of the paper was examined for information on the method of refractive correction during VA testing, type of chart used to measure VA, specifics concerning chart features, testing protocols, and data analysis and means of expressing VA in results. One hundred twenty-eight papers were included. The most common type of charts used were described as logMAR-based. Although most (89.8%) of the studies reported on the method of refractive correction during VA testing, only 58.6% gave the chart design, and less than 12% gave any information whatsoever on chart features or measurement procedures used. The methods used and the approach to analysis were rarely described in sufficient detail to allow others to replicate the study being reported. Sufficient detail should be given on VA measurement to enable others to duplicate the research. The authors suggest that charts adhering to Bailey-Lovie design principles always be used to measure vision in prospective studies and their use encouraged in clinical settings. The distinction between the terms logMAR, an acuity notation, and Bailey-Lovie or ETDRS as chart types should be adhered to more strictly.

Changes in the lower displacement limit for motion with age

Article

Full-text available

Feb 1995

Previous studies have alleged that the ability to perceive motion remains constant with age. We investigated the effect of age on minimum displacement thresholds using computer-generated random dot stimuli in 91 healthy, visually normal subjects (age range 21-82 years). High and low contrast visual acuity and letter contrast sensitivity were also tested. We found that minimum displacement thresholds increased significantly at a rate of 0.07 log min arc per decade (approximately 17%). The relationship between age and performance was very similar for all visual tests.

Repeatability of Visual Acuity Measurement

Article

Full-text available

Jun 1998

This study investigates features of visual acuity chart design and acuity testing scoring methods which affect the validity and repeatability of visual acuity measurements. Visual acuity was measured using the Sloan and British Standard letter series, and Landolt rings. Identifiability of the different letters as a function of size was estimated, and expressed in the form of frequency-of-seeing curves. These functions were then used to simulate acuity measurements with a variety of chart designs and scoring criteria. Systematic relationships exist between chart design parameters and acuity score, and acuity score repeatability. In particular, an important feature of a chart, that largely determines the repeatability of visual acuity measurement, is the amount of size change attributed to each letter. The methods used to score visual acuity performance also affect repeatability. It is possible to evaluate acuity score validity and repeatability using the statistical principles discussed here.

The development of a “reduced logMAR” visual acuity chart for use in routine clinical practice

Article

Full-text available

May 2001

The advantages of logMAR acuity data over the Snellen fraction are well known, and yet existing logMAR charts have not been adopted into routine ophthalmic clinical use. As this may be due in part to the time required for a logMAR measurement, this study was performed to determine whether an abbreviated logMAR chart design could combine the advantages of existing charts with a clinically acceptable measurement time. The test-retest variability, agreement (with the gold standard), and time taken for "single letter" (interpolated) acuity measurements taken using three prototype "reduced logMAR" (RLM) charts and the Snellen chart were compared with those of the ETDRS chart which acted as the gold standard. The Snellen chart was also scored with the more familiar "line assignment" method. The subjects undergoing these measurements were drawn from a typical clinical outpatient population exhibiting a range of acuities. The RLM A prototype chart achieved a test-retest variability of +/-0.24 logMAR compared with +/-0.18 for the ETDRS chart. Test-retest variability for the Snellen chart was +/-0.24 logMAR using clinically prohibitive "single letter" scoring increasing to +/-0.33 with the more usual "line assignment" method. All charts produced acuity data which agreed well with those of the ETDRS chart. "Single letter" acuity measurements using the prototype RLM charts were completed in approximately half the time of those taken using the ETDRS and Snellen charts. The duration of a Snellen "line assignment" measurement was not evaluated. The RLM A chart offers an acceptable level of test-retest variability when compared with the gold standard ETDRS chart, while reducing the measurement time by half. Also, by allowing a faster, less variable acuity measurement than the Snellen chart, the RLM A chart can bring the benefits of logMAR acuity to routine clinical practice.

Repeatability of ETDRS Visual Acuity in Children

Article

Full-text available

Sep 2003
INVEST OPHTH VIS SCI

To evaluate repeatability of the best corrected log minimum angle of resolution (MAR) Early-Treatment Diabetic Retinopathy Study (ETDRS) acuity in a group of 6- to 11-year old children with myopia. Best corrected monocular visual acuity (VA) of a subset of children (n = 86) enrolled in the Correction of Myopia Evaluation Trial (COMET; mean spherical equivalent refractive error -2.35 D with no more than 1.25 D astigmatism) was measured at baseline and 1 month later with ETDRS logMAR charts. Children started with logMAR 0.4 (6/15 or 20/50) and read each letter on all subsequent lines until they missed all letters in 1 line. At baseline, the mean best corrected logMAR VA was 0.003 +/- 0.076 (6/6 or 20/20 +/- 3.8 letters) in the right eye and 0.008 +/- 0.059 (6/6 or 20/20 +/- 2.95 letters) in the left eye. The signed difference between VA measured at baseline and that measured at 1 month was not significantly different from zero in either eye. Repeatability was not associated with age, but a small, statistically significant association with gender was detected in the left eye, with boys approximately 2 letters more variable than girls. The kappa statistic (agreement within 1 line) was good to excellent. Based on the 95% limits of agreement, the criterion for a statistically significant change in VA is no more than +/-0.15 logMAR (or +/-8 letters). This value is similar to those reported for adults and indicates that logMAR VA provides a repeatable measure of acuity in children.

How sensitive to clinical change are ETDRS logMAR visual acuity measurements?

Article

Full-text available

Sep 2003
INVEST OPHTH VIS SCI

To determine the sensitivity to change and specificity achieved when published test-retest variability (TRV) data are used to determine whether measured changes in ETDRS logarithm of the minimum angle of resolution (logMAR) visual acuity reflect true clinical change or are attributable to measurement error alone. Various degrees of change in visual acuity were simulated in a group of normal subjects by adjusting test difficulty through manipulation of viewing distance. Sensitivity to simulated change and specificity were determined with change criteria derived from published Bland-Altman 95% ranges for TRV. The relationship between viewing distance and measured acuity was as predicted theoretically. Simulated acuity change of 0.2 logMAR (two lines of letters) or greater can be reliably distinguished from no change (both sensitivity and specificity >95%) with the ETDRS chart, but a change of 0.1 logMAR or less cannot. The use of 95% ranges for TRV to establish the smallest measured visual acuity change that can be reliably detected ensures a high specificity but does not take account of sensitivity. Use of change criteria derived from published 95% ranges results in a sensitivity of approximately 50% (assuming identical levels of TRV). Sensitivity may be improved by using a change criterion that is smaller than the minimum change sought, providing the change criterion is still at least as large as the 95% range for TRV, so that specificity is maintained. Reducing TRV allows smaller changes in acuity to be reliably detected.

Improving on ETDRS acuities: Design and results for a computerised thresholding device

Article

Full-text available

Sep 2003

All visual acuity data are subject to test-retest variability (TRV). This measurement error obscures true clinical change and reduces the statistical power of clinical trials using acuity as a primary outcome measure. This study was designed to assess whether a computerised system can reduce TRV by taking repeated acuity measurements and averaging them. A computerised system (PC-test) was developed for this purpose and compared in terms of TRV with the current Gold Standard ETDRS logMAR chart. A total of 19 subjects with a mean acuity of +0.16 logMAR (range +0.49 to -0.10 logMAR) were recruited. The performance of two computerised tests (one averaging 10 repeats and one five) was compared with that of the ETDRS logMAR chart in terms of TRV and agreement of acuity data. Results The 10 and five repeat computerised tests (PC-tests) produced a TRV of +/-0.11 and +/-0.10 logMAR, respectively, compared with +/-0.18 logMAR for the ETDRS chart. No significant bias was observed between PC-test and ETDRS acuities. A computerised system that takes repeated acuity measurements and averages them is subject to less TRV than a single ETDRS acuity measurement. A reduced TRV of visual acuity data allows earlier detection of true clinical change in individual patients. It also allows smaller differences between groups to be detected in clinical trials for a given degree of statistical confidence and power.

Development of a clinically feasible logMAR alternative to the Snellen chart: Performance of the "compact reduced logMAR" visual acuity chart in amblyopic children

Article

Full-text available

Nov 2003

The "compact reduced logMAR" (cRLM) chart is being developed as a logMAR alternative to the Snellen chart. It is closer spaced and has fewer letters per line than conventional logMAR charts. Information regarding the performance of such a chart in amblyopes and children is therefore required. This study aimed to investigate the performance of the cRLM chart in amblyopic children. Timed test and retest measurements using two versions of each chart design were obtained on the amblyopic eye of 43 children. Using the methods of Bland and Altman the agreement, test-retest variability (95% confidence limits for agreement, TRV) and test time of the cRLM and the current clinical standard Snellen chart were compared to the gold standard ETDRS logMAR chart. No systematic bias between chart designs was found. For line assignment scoring the respective TRVs were 0.20 logMAR, 0.20 logMAR, and 0.30 logMAR. Single letter scoring TRVs were cRLM (95% CL 0.17) logMAR, ETDRS (95% CL 0.14) logMAR, and Snellen (95% CL 0.29) logMAR. Median testing times were ETDRS 60 seconds, cRLM 40 seconds, Snellen 30 seconds. The sensitivity to change of the cRLM equalled or approached that of the gold standard ETDRS and was at least 50% better than that of Snellen. This enhanced sensitivity to change was at the cost of only a 10 second time penalty compared to Snellen. The cRLM chart was approximately half the width of the ETDRS chart. The cRLM chart may represent a clinically acceptable compromise between the desire to obtain logMAR acuities of reasonable and known sensitivity to change, chart size, and testing time.

Intravitreal triamcinolone as a primary therapy in diabetic macular oedema

Article

Full-text available

May 2005

To evaluate the effect of intravitreal triamcinolone in eyes with diabetic macular oedema that had no previous laser treatment. In all, 12 eyes of 12 patients with diabetic retinopathy, aged 47-70 years (mean 59.2), made up the study. All the eyes had persistent diabetic macular oedema despite having received medical treatment for at least 3 months. In this consecutive case series, none of the eyes received previous laser photocoagulation. Intravitreal injection of 0.1 ml (4 mg) triamcinolone acetonide was offered to treat macular oedema. The visual and anatomic responses were observed as well as complications related to the injection procedure and corticosteroid medication. The follow-up period was between 6 and 10 months (mean 7.9 months) and all eyes completed 6 months of follow-up. Macular oedema was documented for an average of 3.5 months (ranged 3-5 months) before intravitreal corticosteroid injection. Baseline mean central macular thickness was 448.6 microm. At 1 month follow-up, a reduction in mean central macular thickness of 40.8% from 448.6 microm to 265.4 microm was obtained. At 3 and 6 months follow-up, mean central macular thicknesses, were 310 mum and 294.5 mum, respectively. No eyes lost vision at 1 month and 10 eyes (83.2%) showed improvement. At 3 months, no eyes lost vision from baseline and 8 eyes (66.6%) showed improvement. At 6 months, again no eyes lost vision from baseline and 10 eyes (83.2%) maintained improved visual acuity. Intravitreal triamcinolone is a promising therapeutic method in eyes with diabetic macular oedema without previous application of laser treatment. Further study with longer follow-up and large series is warranted to assess the long-term efficacy and safety and the need for retreatment.

Ranibizumab versus Verteporfin for Neovascular Age-Related Macular Degeneration

Article

Full-text available

Oct 2006
NEW ENGL J MED

We compared ranibizumab--a recombinant, humanized, monoclonal antibody Fab that neutralizes all active forms of vascular endothelial growth factor A--with photodynamic therapy with verteporfin in the treatment of predominantly classic neovascular age-related macular degeneration. During the first year of this 2-year, multicenter, double-blind study, we randomly assigned patients in a 1:1:1 ratio to receive monthly intravitreal injections of ranibizumab (0.3 mg or 0.5 mg) plus sham verteporfin therapy or monthly sham injections plus active verteporfin therapy. The primary end point was the proportion of patients losing fewer than 15 letters from baseline visual acuity at 12 months. Of the 423 patients enrolled, 94.3% of those given 0.3 mg of ranibizumab and 96.4% of those given 0.5 mg lost fewer than 15 letters, as compared with 64.3% of those in the verteporfin group (P<0.001 for each comparison). Visual acuity improved by 15 letters or more in 35.7% of the 0.3-mg group and 40.3% of the 0.5-mg group, as compared with 5.6% of the verteporfin group (P<0.001 for each comparison). Mean visual acuity increased by 8.5 letters in the 0.3-mg group and 11.3 letters in the 0.5-mg group, as compared with a decrease of 9.5 letters in the verteporfin group (P<0.001 for each comparison). Among 140 patients treated with 0.5 mg of ranibizumab, presumed endophthalmitis occurred in 2 patients (1.4%) and serious uveitis in 1 (0.7%). Ranibizumab was superior to verteporfin as intravitreal treatment of predominantly classic neovascular age-related macular degeneration, with low rates of serious ocular adverse events. Treatment improved visual acuity on average at 1 year. (ClinicalTrials.gov number, NCT00061594 [ClinicalTrials.gov].).

Ranibizumab for Neovascular Age-Related Macular Degeneration

Article

Full-text available

Oct 2006
NEW ENGL J MED

Ranibizumab--a recombinant, humanized, monoclonal antibody Fab that neutralizes all active forms of vascular endothelial growth factor A--has been evaluated for the treatment of neovascular age-related macular degeneration. In this multicenter, 2-year, double-blind, sham-controlled study, we randomly assigned patients with age-related macular degeneration with either minimally classic or occult (with no classic lesions) choroidal neovascularization to receive 24 monthly intravitreal injections of ranibizumab (either 0.3 mg or 0.5 mg) or sham injections. The primary end point was the proportion of patients losing fewer than 15 letters from baseline visual acuity at 12 months. We enrolled 716 patients in the study. At 12 months, 94.5% of the group given 0.3 mg of ranibizumab and 94.6% of those given 0.5 mg lost fewer than 15 letters, as compared with 62.2% of patients receiving sham injections (P<0.001 for both comparisons). Visual acuity improved by 15 or more letters in 24.8% of the 0.3-mg group and 33.8% of the 0.5-mg group, as compared with 5.0% of the sham-injection group (P<0.001 for both doses). Mean increases in visual acuity were 6.5 letters in the 0.3-mg group and 7.2 letters in the 0.5-mg group, as compared with a decrease of 10.4 letters in the sham-injection group (P<0.001 for both comparisons). The benefit in visual acuity was maintained at 24 months. During 24 months, presumed endophthalmitis was identified in five patients (1.0%) and serious uveitis in six patients (1.3%) given ranibizumab. Intravitreal administration of ranibizumab for 2 years prevented vision loss and improved mean visual acuity, with low rates of serious adverse events, in patients with minimally classic or occult (with no classic lesions) choroidal neovascularization secondary to age-related macular degeneration. (ClinicalTrials.gov number, NCT00056836 [ClinicalTrials.gov].).

Comparison of Visual Acuity in Macular Degeneration Patients Measured with Snellen and Early Treatment Diabetic Retinopathy Study Charts

Article

Full-text available

Feb 2008

To compare the measurements of visual acuity (VA) results measured with Snellen and Early Treatment Diabetic Retinopathy Study (ETDRS) charts in eyes with and without age-related macular degeneration (AMD). Cross-sectional study. One hundred four participants (190 eyes) selected from a university retina practice; 80 participants (142 eyes) had some degree of AMD. Visual acuity was measured in each patient using standard procedure with both Snellen and ETDRS charts in random order. Statistical analysis of the results was performed. Difference in VA measured by both charts in logarithm of minimal angle of resolution (logMAR) notations. Overall, the mean Snellen VA was 0.78 logMAR (= 20/120), and the mean ETDRS VA in the same eye was 0.54 logMAR (= 20/70; P<0.001). In the low vision group (<20/200), represented by patients with AMD, the average difference in number of lines was considerably larger than in the good vision range (>20/30). On average, 20/200 on Snellen was 20/95 on ETDRS (>3 lines difference), and 20/30 on Snellen was 20/25 on ETDRS (<1 line difference). Our results show poor agreement between the Snellen and ETDRS charts, and it was more pronounced in the group with poor vision. The ETDRS measurements yielded better VA, particularly in participants with vision <20/200 (representing more advanced AMD patients). We suggest taking these findings into consideration when comparing outcomes in clinical practices (which typically measure VA using standard Snellen charts) with outcomes from clinical trials (which typically measure VA using ETDRS charts).

Intravitreal Bevacizumab for Treatment of Neovascular Age-related Macular Degeneration: A One-year Prospective Study

Article

Full-text available

Mar 2008
AM J OPHTHALMOL

To investigate the efficacy of intravitreal bevacizumab for treatment of neovascular age-related macular degeneration (AMD). Prospective, open-label, nonrandomized clinical study. Sixty patients (60 eyes) with subfoveal choroidal neovascular membrane (CNV) attributable to AMD participated in this study at the American University of Beirut and Hotel Dieu de France Retina Clinics. All lesion types were included except for retinal angiomatous proliferation. In the initial treatment phase, intravitreal bevacizumab (2.5 mg/0.1 ml) was given at baseline, and then two additional monthly injections were given if the macula was not dry on optical coherence tomography. The criteria for re-injection after the induction phase were presence of new fluid in the macula, increased central retinal thickness (CRT) at least 100 microm, loss of at least five letters of vision with increased fluid in the macula, new classic CNV or new macular hemorrhages. Main outcome measure was the proportion of eyes losing <15 letters of vision after 12 months. Fifty-one patients (51 eyes) completed the 12 months. Mean visual acuity improved from 45.7 letters at baseline to 53.1 letters at 12 months (P = .004), and 47 eyes (92.2%) lost <15 letters. Mean CRT decreased from 327.4 microm at baseline to 227.8 microm at 12 months (P < .001). A mean of 3.4 injections were given over the course of the study, and no ocular or systemic side-effects were noted. Eyes with neovascular AMD treated with intravitreal bevacizumab over 12 months had significant anatomical and functional improvement. Further studies need to confirm the long-term efficacy of this treatment.

Comparison of three types of test target for the measurement of visual acuity

Article

Jan 1952

A randomized trial comparing intravitreal triamcinolone acetonide and focal/grid photocoagulation for diabetic macular oedemaDiabetic Retinopathy Clinical Research Network OphthalmologyOphthalmology200811514471459274826418662829

Article

Sep 2008
OPHTHALMOLOGY

Objective: To evaluate the efficacy and safety of 1-mg and 4-mg doses of preservative-free intravitreal triamcinolone in comparison with focal/grid photocoagulation for the treatment of diabetic macular edema (DME). Design: Multicenter, randomized clinical trial. Participants: Eight hundred forty study eyes of 693 subjects with DME involving the fovea and with visual acuity of 20/40 to 20/320. Methods: Eyes were randomized to focal/grid photocoagulation (n = 330), 1 mg intravitreal triamcinolone (n = 256), or 4 mg intravitreal triamcinolone (n = 254). Retreatment was given for persistent or new edema at 4-month intervals. The primary outcome was evaluated at 2 years. Main Outcome Measures: Visual acuity measured with the electronic Early Treatment Diabetic Retinopathy Study method (primary), optical coherence tomography-measured retinal thickness (secondary), and safety. Results: At 4 months, mean visual acuity was better in the 4-mg triamcinolone group than in either the laser group (P<0.001) or the 1-mg triamcinolone group (P = 0.001). By 1 year, there were no significant differences among groups in mean visual acuity. At the 16-month visit and extending through the primary outcome visit at 2 years, mean visual acuity was better in the laser group than in the other 2 groups (at 2 years, P = 0.02 comparing the laser and 1-mg groups, P = 0.002 comparing the laser and 4-mg groups, and P = 0.49 comparing the 1-mg and 4-mg groups). Treatment group differences in the visual acuity outcome could not be attributed solely to cataract formation. Optical coherence tomography results generally paralleled the visual acuity results. Intraocular pressure increased from baseline by 10 mmHg or more at any visit in 4%, 16%, and 33% of eyes in the 3 treatment groups, respectively, and cataract surgery was performed in 13%, 23%, and 51 % of eyes in the 3 treatment groups, respectively. Conclusions: Over a 2-year period, focal/grid photocoagulation is more effective and has fewer side effects than 1-mg or 4-mg doses of preservative-free intravitreal triamcinolone for most patients with DME who have characteristics similar to the cohort in this clinical trial. The results of this study also support that focal/grid photocoagulation currently should be the benchmark against which other treatments are compared in clinical trials of DME.

Mycorrhizal associations in Polylepis woodlands of Central Argentina

Article

Jan 2007
CAN J BOT

Reproducibility of Refraction and Visual Acuity Measurement Under A Standard Protocol

Article

Jan 1989
RETINA-J RET VIT DIS

The authors present results of a study in which certified visual acuity examiners in the Macular Photocoagulation Study Group, performed independent replicate refractions and visual acuity measurements on both eyes of patients whose visual acuities ranged from 20/20 to <20/800. Patients with neovascular age-related macular degeneration (AMD), ocular histoplasmosis, or idiopathic neovascularization were represented. A total of 328 observations for 164 eyes from 82 patients were available for analysis. Overall reliabilities of the refraction data and the visual acuity data were 98.9% and 98.7%, respectively. Differences between replicate measurements were small; 87% were less than one line. However, differences were greater in patients with visual acuity <20/100 and in patients with AMD. These results indicate that the reliability of refraction and visual acuity measurements under a standard protocol is high and may depend on both visual acuity level and disease process. If a standard, systemic procedure is used for refraction and visual acuity testing, the clinician may be able to differentiate between true changes and measurement error, even among low vision patients with AMD. RETINA 9:163-169, 1989 (C) The Ophthalmic Communications Society, Inc.

New Design Principles for Visual Acuity Letter Charts

Article

Dec 1976
Am J Optom Physiol Optic

This paper intoduces new principles for the design and use of letter charts for the measurement of visual acuity. It is advocated that the test task should be essentially the same at each size level on the chart. Such standardization of the test task requires the use of letters of equal legibility, the same number of letters on each row, and uniform between-letter and between-row spacing. It is also advocated that, combined with the test task standardization, there should be a logarithmic progression of letter size. Charts incorporating these design features have been made. These charts facilitate the use of nonstandard testing distances which might be used when there is low visual acuity, when examination room layout prevents testing at the standard distance, or when it is necessary to validate visual acuity scores or detect malingering. Adjusting the visual acuity score according to the chosen testing distance is simplified by the use of logarithmic scaling.

Clinical experience with the surgical removal of subfoveal neovascular membranes: Short-term postoperative results

Article

Jul 1992
OPHTHALMOLOGY

Severe visual loss occurs in the presumed ocular histoplasmosis syndrome (POHS) and in age-related macular degeneration (ARMD) from subfoveal neovascularization. Although laser photocoagulation has recently been recommended for this complication in ARMD, treatment is inevitably associated with a loss of central vision. In an attempt to restore and/or preserve central vision, the authors undertook surgical removal of subfoveal neovascular membranes in these diseases. Patients with POHS and ARMD with reduced Snellen visual acuity to 20/80 or less were selected if there was angiographic evidence of a neovascular membrane beneath the fovea. Modern vitreoretinal techniques were used to remove the subfoveal neovascular complex. The authors' first 15 patients with POHS and 19 patients with ARMD were followed for an average of 4 months postoperatively. Snellen visual acuity improved by 2 lines or more in 8 of 15 (53%) cases of POHS. Although similar improvements in Snellen visual acuity were not observed in cases of ARMD, 14 of 19 (74%) cases showed either slight improvement or stabilization of their vision postoperatively. Complications included recurrent neovascularization in 2 of 15 (13%) and 3 of 19 (16%) eyes with POHS and ARMD, respectively. No retinal detachment or preretinal proliferation was observed. These results suggest that subfoveal neovascularization can be successfully removed with preservation of foveal vision in POHS and stabilization in ARMD, at least for the short term. Visual improvement was observed in POHS even after 6 months of decreased vision. Finally, visual prognosis is most dependent on the integrity of the subfoveal RPE after removal of the membrane.

Reproducibility of refraction and visual acuity measurement under a standard protocol. The Macular Photocoagulation Study Group

Article

Feb 1989
RETINA-J RET VIT DIS

The authors present results of a study in which certified visual acuity examiners in the Macular Photocoagulation Study Group, performed independent replicate refractions and visual acuity measurements on both eyes of patients whose visual acuities ranged from 20/20 to less than 20/800. Patients with neovascular age-related macular degeneration (AMD), ocular histoplasmosis, or idiopathic neovascularization were represented. A total of 328 observations for 164 eyes from 82 patients were available for analysis. Overall reliabilities of the refraction data and the visual acuity data were 98.9% and 98.7%, respectively. Differences between replicate measurements were small; 87% were less than one line. However, differences were greater in patients with visual acuity less than 20/100 and in patients with AMD. These results indicate that the reliability of refraction and visual acuity measurements under a standard protocol is high and may depend on both visual acuity level and disease process. If a standard, systemic procedure is used for refraction and visual acuity testing, the clinician may be able to differentiate between true changes and measurement error, even among low vision patients with AMD.

Study of Chart Designs and Optotypes for Preschool Vision Screening - I. Comparability of Chart Designs

Article

Jul 1989

Design variations in children's distance vision screening charts contribute to inconsistencies noted in preschool vision screening programs. This study compares children's distance visual acuity on two chart designs: logarithm of the minimal angle of resolution (LOGMAR) vs a chart of 'standard' design. In theory, the LOGMAR chart offers the advantages of improved precision in measuring inter-patient differences and greater consistency of follow-up measurements. Our findings indicate the following: 1) the ability to complete a test depends upon the child's age, not on chart design; 2) isolation of symbols is required more frequently for the LOGMAR charts than for the standard charts; and 3) on average, children have slightly poorer visual acuity scores on LOGMAR charts than on standard charts.

Standardized Illumination for Visual Acuity Testing in Clinical Research

Article

Aug 1982
AM J OPHTHALMOL

We have designed two boxes, one using direct illumination and the other using retroillumination, to light high-contrast visual acuity charts during testing. The evenness of the lighting eliminated one of the variables in visual acuity testing.

New Visual Acuity Charts for Clinical Research

Article

Aug 1982
AM J OPHTHALMOL

Three new visual acuity charts facilitate quantitative use of visual acuity test results. The charts have high-contrast lettering on washable white polystyrene. Each line has five Sloan letters; the lines are of equal difficulty and there is a geometric progression in letter size from line to line. This provides a similar task for each line on the chart with the letter size being the only variable. Charts with different letter sequences are used for testing right and left eyes.

Observer variation in Ophthalmology

Article

Jul 1980

Data collected by clinicians and nurses from patients with clinically diagnosed lens opacities revealed that there was poor repeatability of the description of the position of lens opacities, statistically significant observer variation in determining visual acuity, and good repeatability as to what visual tasks the patient can perform. It is suggested that clinicans should give more weight to the visual handicap revealed by performance of visual tasks in making a decision for cataract surgery than at present.

Visual Acuity Changes Throughout Adulthood in Normal, Healthy Eyes: Seeing Beyond 6/6

Article

Apr 1995

There are many useful longitudinal and cross-sectional epidemiological studies of how visual acuity (VA) deteriorates with age. However, few studies have evaluated age-related VA changes in normal, healthy eyes. Data from three previous studies that included VA measurements taken with logMAR charts from subjects with normal, healthy eyes were collated and additional data from 42 subjects were added. This provided VA results from 223 subjects (age range 18 to 80 years). Mean logMAR VA improved from -0.13 (Snellen equivalent 6/4.5) in 18- to 24-year-olds to -0.16 (Snellen 6/4(-1)) in 25- to 29-year-olds and then gradually became worse with age to a mean value of -0.02 (Snellen 6/6+1) for subjects over 75 years of age. The inadequacy of 6/6 as a norm value of VA is illustrated. The data show VA levels far superior to the data from the standard references of Pitts (1982) and Weale. (1975, 82) We suggest that this is because we used logMAR charts (providing nontruncated data), the subject's optimal refractive correction (rather than habitual) and strict exclusion criteria ensuring that only subjects with normal, healthy eyes were recruited for the studies.

Standardizing the Measurement of Visual Acuity for Clinical Research Studies

Article

Feb 1996
OPHTHALMOLOGY

Variability of measurements of visual acuity in a large eye clinic

Article

Jan 2000

The aim of this study was to determine the variability of visual acuity in a large eye clinic. A cross-sectional study using 50, consecutively presenting adult patients with visual acuity of at least 6/60 and aged between 18 and 75 years was performed. Measurements of visual acuity obtained under normal clinical conditions were compared to measurements obtained using standard clinical research protocols. The variability of visual acuity was assessed by determining the 95% limits of agreement between test and retest measures. There were no significant differences between test-retest measurements of visual acuity, either aided or unaided. Pearson r correlation coefficients between test and retest measurements were high for both aided and unaided visual acuity. The 95% limits of agreement revealed repeatability of about +/-1.5 logMAR or 1.5 lines on a standard logMAR chart. In large eye clinics, in order to be confident that a real change in visual acuity has occurred between measurements, a difference of at least 0.15 logMAR (8 letters on a standard logMAR visual acuity chart) is required.

Chart construction and letter legibility/readability

Article

Nov 1999

Charles Mcmonnies

Variation in legibility/readability between charts letters may be due to differences in chart construction and/or examination protocols and/or subject selection. An examination of legibility/readability of letters that are common to two chart constructions was undertaken. Identical examination and subject selection protocols for both charts were employed. It was found that ranking of error frequencies for some letters varied between the Bausch & Lomb Compact Acuity Projector and Bailey-Lovie charts. Despite many similarities in ranking, the differences found for the letters D and E indicate that caution should be observed before assuming that legibility/readability determined with one letter chart would apply when using another. Lack of standardisation for chart construction, as well as measurement methods and conditions of measurement, invalidate inter-practice comparisons for visual acuity.

Letter legibility and chart equivalence

Article

Apr 2000

We tested the appropriateness of the assumption that charts, which only vary in having different sequences of five letters per line, chosen from the same 10 letter set, can be regarded as equivalent for the purpose of making valid comparisons of visual acuity. Visual acuity findings from samples of 400 patients, for each of two nominally equivalent Bailey-Lovie charts, have been used to determine the relative legibility of individual letters and lines, using the percentage incorrect method of analysis. The chance of error for the hardest letter is approximately 13 times greater than for the easiest letter on each chart. Significant between-chart differences in error rates for the hardest letters ('F' and 'H') were found. Some letters that have adjacent ranks on the legibility scale were found to have significantly different legibility. Significant differences in difficulty can occur for the same nominal line on apparently equivalent charts because of chance combinations of easier or harder letters in that line. Uneven line-to-line scale intervals have been confirmed for the charts examined, by showing corresponding differences in the distributions of lines of threshold acuity. The use of varying examination distances may be inappropriate for Bailey-Lovie (or similar) charts that depart from their nominal interval scaling. When different versions of these charts are assumed to be equivalent, the discrepancy between repeated measurements may be significantly increased. There is the possibility of increasing measurement precision using charts having different sequences of the same 10 letters in each line to achieve equal scaling of line intervals. Equivalent charts can be validly constructed using different sequences of the same 10 letters in each line.

Repeatability and Intercorrelations of Standard Vision Tests as a Function of Age

Article

Aug 2000

We assessed repeatability and intercorrelations of five standard vision tests in subjects with normal vision. Seventy-eight subjects (aged 21 to 68 years) completed five measurements each of high- and low-contrast visual acuity, near visual acuity and contrast sensitivity (Pelli-Robson chart). Except for correlations between high- and low-contrast visual acuity (r = 0.78), intercorrelations between tests were low to moderate (r < 0.5). For each measure, variability for the group was about one line on the chart (one triplet for the Pelli-Robson chart) and the minimum variability for an individual subject was about one third of this. On average, 1 to 2 lines can be expected to be lost over the normal lifespan on each test. Variability in responses did not increase significantly with age for any test. The criterion for judging change on commonly used clinical vision tests is about one line for subjects over a wide age range.

Reliability of Snellen charts for testing visual acuity for driving: Prospective study and postal questionnaire

Article

Nov 2000

To assess the ability of patients with binocular 6/9 or 6/12 vision on the Snellen chart (Snellen acuity) to read a number plate at 20.5 m (the required standard for driving) and to determine how health professionals advise such patients about driving. Design: Prospective study of patients and postal questionnaire to healthcare professionals. 50 patients with 6/9 vision and 50 with 6/12 vision and 100 general practitioners, 100 optometrists or opticians, and 100 ophthalmologists. Ophthalmology outpatient clinics in Sheffield. Ability to read a number plate at 20.5 m and health professionals' advice about driving on the basis of visual acuity. 26% of patients with 6/9 vision failed the number plate test, and 34% with 6/12 vision passed it. Of the general practitioners advising patients with 6/9 vision, 76% said the patients could drive, 13% said they should not drive, and 11% were unsure. Of the general practitioners advising patients with 6/12 vision, 21% said the patients could drive, 54% said they should not drive, and 25% were unsure. The level of acuity at which optometrists, opticians, and ophthalmologists would advise drivers against driving ranged from 6/9(-2) (ability to read all except two letters on the 6/9 line of the Snellen chart) to less than 6/18. Snellen acuity is a poor predictor of an individual's ability to meet the required visual standard for driving. Patients with 6/9 vision or less should be warned that they may fail to meet this standard, but those with 6/12 vision should not be assumed to be below the standard.

Visual acuity testing in diabetic subjects: The decimal progression chart versus the Freiburg visual acuity test

Article

Aug 2003

Lars Loumann Knudsen

To study reproducibility and biological variation of visual acuity in diabetic maculopathy, using two different visual acuity tests, the decimal progression chart and the Freiburg visual acuity test. Twenty-two eyes in 11 diabetic subjects were examined several times within a 12-month period using both visual acuity tests. The most commonly used visual acuity test in Denmark (the decimal progression chart) was compared to the Freiburg visual acuity test (automated testing) in a paired study. Correlation analysis revealed agreement between the two methods (r(2)=0.79; slope=0.82; y-axis intercept=0.01). The mean visual acuity was found to be 15% higher (P<0.0001) with the decimal progression chart than with the Freiburg visual acuity test. The reproducibility was the same in both tests (coefficient of variation: 12% for each test); however, the variation within the 12-month examination period differed significantly. The coefficient of variation was 17% using the decimal progression chart, 35% with the Freiburg visual acuity test. The reproducibility of the two visual acuity tests is comparable under optimal testing conditions in diabetic subjects with macular oedema. However, it appears that the Freiburg visual acuity test is significantly better for detection of biological variation.

Effect of lesion size, visual acuity, and lesion composition on visual acuity change with and without verteporfin therapy for choroidal neovascularization secondary to age-related macular degeneration: TAP and VIP report no. 1

Article

Oct 2003
AM J OPHTHALMOL

To determine whether differences in baseline lesion size and visual acuity might explain differing results found in three different lesion compositions (predominantly classic, minimally classic, and occult with no classic) among three placebo-controlled, randomized clinical trials evaluating photodynamic therapy with verteporfin (Visudyne, Novartis AG), also termed verteporfin therapy, in patients with subfoveal choroidal neovascularization (CNV) due to age-related macular degeneration (AMD). Exploratory analyses were conducted in patients with predominantly classic or minimally classic lesions at enrollment in the Treatment of AMD with Photodynamic Therapy (TAP) Investigation and in AMD patients with occult with no classic CNV in the Verteporfin In Photodynamic Therapy (VIP) Trial. Baseline characteristics of patients among these three lesion compositions were compared. In addition, multiple linear regression modeling was used to explore the effect of baseline lesion size, visual acuity, and lesion composition on mean change in visual acuity from baseline to 24 months. At baseline, the mean size of predominantly classic lesions (3.4 disk areas) was smaller than that of minimally classic (4.7 disk areas) and occult with no classic lesions (4.3 disk areas). In the multiple linear regression model of individual lesion compositions, there was a significant treatment-by-lesion-size interaction for minimally classic and occult with no classic lesions, but not for predominantly classic lesions. Interaction between treatment and baseline visual acuity was not significant for any lesion composition. Small verteporfin-treated lesions lost less vision than large verteporfin-treated lesions in each lesion composition. In the multiple linear regression model that included all lesion compositions, lesion size was a more significant predictive factor for the magnitude of treatment benefit than either lesion composition or visual acuity. Smaller (4.0 disk areas or less) minimally classic and occult with no classic lesions had similar visual acuity outcomes to those observed in predominantly classic lesions. Based on exploratory analyses, lesion size in the TAP Investigation and VIP Trial was an important predictor of the magnitude of treatment benefit with verteporfin therapy in occult with no classic and minimally classic lesion compositions. In patients with AMD, treating smaller rather than larger neovascular lesions, regardless of lesion composition, likely will result in a better level of visual acuity.

Contour Interaction and Visual Resolution: Contralateral Effects

Article

Dec 1963

Detection of the gap in a four-position Landolt C presented to one eye is impaired by critically spaced surrounding bars seen only by the other eye. The intensity and spatial extent of this contralateral contour interaction match those obtained ipsilaterally. These results indicate that the neural site for this loss of visual information is supraretinal.

Random measurement error in visual acuity measurement in clinical settings

Article

Jun 2005

To estimate the random measurement error in visual acuity (VA) determination in the clinical environment in cataractous, pseudophakic and healthy eyes. The VAs of patients referred for cataract surgery or consultation by ophthalmic professionals were re-examined and the VA results for distance using projector acuity charts were compared. Refractive errors were also remeasured. A total of 99 eyes (41 cataractous, 36 pseudophakic and 22 healthy eyes) were examined. The healthy comparison group consisted of hospital staff. Only one eye of each person and eyes with Snellen VAs of 0.3-1.3 (logMAR 0.52 to - 0.11) were included. The mean time interval between the first and second examinations was 45 days. The estimated standard deviation of measurement error (SDME) of repeated VA measurements of all eyes was logMAR 0.06. Eyes with the lowest VA (0.3-0.45) had the largest variability (SDME logMAR 0.09), and eyes with VA > or = 0.7 had the smallest (SDME logMAR 0.04). The variability may be partly explained by the line size progression in lower VAs, partly by the difference in the remeasurement of the refractive error. The difference in the average VA between examinations 1 and 2 (logMAR 0.15 versus 0.12) was considered to be of some interest because it indicates that some learning effect is possible. Visual acuity results in clinical settings have a certain degree of inherent variability. In this series variability ranged from SDME logMAR 0.04 (eyes with good vision) to logMAR 0.09 (in the lower vision group) in the Snellen VA range of 0.3-1.3. Changes should be judged with caution, especially in cases of decreased VA.

Intravitreal Cortisone Injection for Refractory Diffuse Diabetic Macular Edema

Article

Jan 2006

Purpose: The purpose of this study was to evaluate the safety and efficacy of intravitreal triamcinolone acetonide injection in patients with diffuse diabetic macular edema. We also compared the effect of intravitreal triamcinolone with macular grid laser photocoagulation in macular edema. Patients and methods: Thirty patients with diabetic diffuse macular edema unresponsive to grid laser photocoagulation for at least 4 months received 0.1 ml (4 mg/ml) intravitreal triamcinolone acetonide (Kenakort-A) injection as treatment. This study group was compared with a control group of 30 patients (30 eyes) who had undergone grid laser macular coagulation. Mean follow-up time was 17 months (range 14-24 months) in the study group and 19 months (range 16-24 months) in the control group. Results: In the study group, mean improvement in visual acuity measured 3.8, 3.4, 0.9 and 0.2 Snellen lines at the follow-up intervals of 1, 3, 6 and 12 months, respectively. Improvement in visual acuity was statistically significant only at 1 month (p = 0.002) and 3 months (p = 0.003) after injection. Visual acuity was significantly (p < 0.05) better in the study group than the control group at 1 and 3 months. Overall, 6 of 30 eyes (20%) required a second injection and 3 eyes (10%) a third due to regression in visual acuity. Towards the end of the follow-up period, the visual acuity decreased to almost baseline levels. Elevation of intraocular pressure was found in 4 patients and controlled with topical antiglaucomatosis treatment. Sterile endophthalmitis was detected in only one eye. No eye exhibited cataract progression during the follow-up period. Conclusion: Intravitreal injection of triamcinolone may be beneficial for temporarily increasing visual acuity in patients with diabetic diffuse macular edema who are unresponsive even to grid laser photocoagulation. But the regression of visual acuity looks inevitable in the long term after injection. Therefore, repeated injections with/without increasing doses might be required for the stabilization of visual acuity.

Reliability and Consistency of Visual Acuity and Contrast Sensitivity Measures in Advanced Eye Disease

Article

Dec 2005

The purpose of this article is to establish reliability of standard visual function measures in patients with severe vision loss. Legally blind subjects were enrolled in a repeated-measures study to determine the reproducibility of a battery of psychophysical vision measures. Tests reported here include ETDRS visual acuity (VA) under regular and dim illumination and Pelli-Robson letter contrast sensitivity (CS) under regular, dim, and glare conditions. Two to five test repetitions were performed at monthly intervals. Subject groups included retinitis pigmentosa (RP) (n = 29), macular disease (MD) (n = 17), optic nerve disease (ON) (n = 4), diabetic retinopathy (DR) (n = 5), and other retinal diseases (OR) (n = 10). For most subject groups, VA measures had mean 95% coefficient of repeatability (CR.95) of 0.20 (group means between 0.13 and 0.36) log units, and CS measures had mean CR.95 of 0.35 (group means between 0.19 and 0.48) log units. The established reliability of VA and CS tests in subjects with severe visual impairments will allow investigators to determine whether a significant change in vision has occurred during future clinical trials to reverse, halt, or slow vision loss. The criterion for change needs to be larger than for normally sighted controls, i.e., approximately two to three lines for VA and between eight to 11 letters for CS.

Comparison of visual acuities at different distances and defocus curves

Article

Dec 2002

To evaluate how visual acuities at different distances correlate with results from defocus curves. Department of Ophthalmology and Institute of Medical Physics, University of Vienna, Medical School, Vienna, and Department of Ophthalmology, Krankenhaus St. Pölten, St. Pölten, Austria. This study comprised 15 eyes of 14 patients with a mean age of 67.9 years +/- 9.7 (SD) with a monofocal silicone intraocular lens (911A, Pharmacia). The best corrected distance visual acuity was determined at viewing distances of 6 m, 2 m, 1 m, 67 cm, 50 cm, 40 cm, and 33 cm using logMAR charts. Defocus curves were then evaluated from -3.0 to -0.5 diopter (D) at 0.5 D increments from the best distance correction at a viewing distance of 6 m. The mean distance visual acuity was logMAR 0.08 +/- 0.07. The visual acuity graph from the testing at different distances was above the defocus graph at all testing points. Comparison of the visual acuity results from the 2 tests revealed statistically significant differences in the range from 2 m (-0.5 D) to 33 cm (-3.0 D). Results of defocus curves disregard the diminutions of minus glasses, the normally restricted viewing distance to 6 m for distance acuity determination, and in particular the physiological miosis caused by the near-point reaction.

Ranibizumab: Phase III Clinical Trial Results

Article

Oct 2006
Ophthalmol Clin

Ranibizumab therapy is the first treatment for neovascular AMD to improve vision for most patients. The benefits apply to all angiographic subtypes of neovascular AMD and across all lesion sizes. Although the pivotal phase III trials (MARINA and ANCHOR) used monthly injections of ranibizumab for 2 years, the ongoing PIER, PrONTO, and SAILOR trials are investigating less frequent dosing regimens, and preliminary results from the PrONTO study suggest that fewer injections will most likely result in visual acuity improvements similar to the results from the phase III trials. When comparing the ANCHOR results with the FOCUS results, it also becomes apparent that the combination of ranibizumab with PDT does not necessarily result in better visual acuity outcomes, and the use of PDT may even reduce the visual acuity benefits achieved with ranibizumab alone (see Figs. 1-3). It seems unlikely that combination therapy provides any significant advantage over ranibizumab alone unless the combination of PDT and ranibizumab can decrease the need for frequent retreatment. The results from the PrONTO Study already suggest that less frequent treatment with ranibizumab is possible by using a variable dosing regimen with OCT. Ranibizumab also seems to be safe, with the 2-year MARINA data showing no increase in the incidence of systemic adverse events that could be associated with anti-VEGF therapy, such as myocardial infarction and stroke. There was a hint of a safety concern, however, in the pooled 1-year safety results from the MARINA and ANCHOR trials. Although the combined rate of myocardial infarction and stroke during the first year of the ANCHOR and MARINA trials was similar in the control and the 0.3-mg ranibizumab arms (1.3% and 1.6% respectively), these adverse events were slightly higher in the 0.5-mg ranibizumab arm (2.9%). These differences are not statistically significant, however, and probably do not represent a dose-dependent increase in risk because the 2-year results from the MARINA trial with the same monthly injection regimen showed no increased risk of thromboembolic events. In December 2005, Genentech submitted a Biologics License Application to the FDA for the use of ranibizumab in the treatment of neovascular wet AMD based on 1-year clinical efficacy and safety data from the two pivotal phase III trials, ANCHOR and MARINA, and the phase I-II FOCUS trial. Genentech has been granted a 6-month Priority Review from the FDA with a decision anticipated 6 months from the December submission date or by the end of June 2006 [29]. By the summer of 2006, this revolutionary therapy should be available for the treatment of neovascular AMD. At that time, the major dilemma facing most retina specialists will be whether to use intravitreal ranibizumab or intravitreal bevacizumab, the low cost alternative, for the treatment of neovascular AMD.

Comparison of logMAR ETDRS chart and a new computerised staircased procedure for assessment of the visual acuity of children

Article

Dec 2006

The validity and repeatability of visual acuity measures are particularly important in the detection and monitoring of childhood visual anomalies such as amblyopia. The repeatability and sensitivity of a new computerised visual acuity test, 'Staircased Procedure' is compared with the now gold standard visual acuity test, the early treatment of diabetic retinopathy study (ETDRS). Twenty-seven visually normal children (mean age: 6.7 +/- 1.1 years) and 27 children with amblyopia (mean age: 6.1 +/- 0.7 years) were tested with the ETDRS and Staircased Procedure. A retest was administered 4-5 weeks later and 30 min later for the visually normal and the amblyopic children, respectively. The staircased procedure produced significantly better visual acuity than the ETDRS for visually normal and amblyopic children. Repeatability was similar for both tests (ETDRS: 0.11 log units; staircased procedure: 0.13 log units). In conclusion, the Staircased Procedure was an acceptable test with high repeatability and validity.

Pedersen R, Soliman W, Lund-Andersen H, Larsen M. Treatment of choroidal neovascularization using intravitreal bevacizumab

Article

Sep 2007

This study aimed to assess the pharmacodynamic profile of intravitreal bevacizumab in relation to best corrected visual acuity (BCVA), foveal thickness, and other aspects of macular morphology after intravitreal injection of bevacizumab in eyes with subretinal choroidal neovascularization (CNV). A retrospective observational, uncontrolled case series including 26 eyes in 25 patients followed for up to 6 months after intravitreal injection of bevacizumab 1 mg repeated as deemed necessary after monthly assessments by biomicroscopy, optical coherence tomography, colour fundus photography, fluorescein angiography and BCVA determination. At follow-up, cases were classified by morphological treatment response (reduction or elimination of pathological neovascular leakage, retinal thickening or serous retinal detachment) or absence of response (deterioration or lack of improvement). Primary disease entities included age-related macular degeneration (22 eyes, four of which had evidence of retinal angiomatous proliferation), idiopathic peripapillary neovascularization (one eye), and angioid streaks (three eyes in two patients). One month after the first injection, apparent morphological improvement was observed in 24/26 eyes and mean BCVA had improved by 3.1 +/- 7.8 letters (p = 0.05). Of these 24 responders, which included all primary diagnoses, 11 (46%) demonstrated BCVA improvement of >or= 5 letters. The two non-responders (7.7%) had lost > 3 lines of vision at 2 months follow-up. Overall, 18 eyes completed 6 months follow-up, with a mean BCVA improvement of 0.5 +/- 12.7 letters, and 22 eyes completed 3 months follow-up, with a mean BCVA improvement of 2.0 +/- 11.0 letters. Two months after the first injection, 11 (46%) of the 24 responders demonstrated signs of recurrent CNV activity, defined as decreased BCVA and/or increased retinal thickness and/or fluorescein angiographic CNV leakage. No serious drug-related adverse events were observed during the course of the study. Overall mean BCVA remained stable throughout the study. Morphological signs of reduced CNV activity were seen in the majority of eyes at 2-4 weeks after intravitreal bevacizumab injection. Half the responders showed signs of renewed CNV activity at 2 months after their first injection. All first-injection responders were also second-injection responders.

Reliability of the electronic Early Treatment Diabetic Retinopathy Study testing protocol in children 7 to <13 years old

Article

Oct 2003
AM J OPHTHALMOL

To assess the test-retest reliability of the electronic Early Treatment Diabetic Retinopathy Study (E-ETDRS) visual acuity algorithm using the computerized Electronic Visual Acuity (EVA) tester in children 7 to <13 years old. Test-retest reliability study. This multicenter study involved 245 subjects at four clinical sites. As the main outcome measure, visual acuity was measured twice using the E-ETDRS testing protocol on the EVA system, which uses a programmed handheld device to communicate with a personal computer and a 17-inch monitor at a 3-m test distance. Test-retest reliability was high (r =.94 for right eyes and 0.96 for left eyes) and for both right and left eyes, 89% of retest scores were within 0.1 logarithm of the minimal angle of resolution (logMAR) (five letters) of the initial test score and 99% of retests were within 0.2 logMAR (10 letters). Reliability was high across the age range of 7 to <13 years. Based on 95% confidence level estimates, a change in visual acuity of 0.2 logMAR (10 letters) from a previous acuity measure is unlikely to result from measurement variability. The E-ETDRS protocol using the EVA has high test-retest reliability in children 7 to <13 years of age. Potential advantages include better standardization across multiple sites, the ability to directly capture data electronically with an automatic acuity score calculation, the reduction of potential bias by limiting the tester's role, and the requirement of only a single testing distance for measurements from 20/800 to 20/12. This computerized testing method should be considered when visual acuity is used as an outcome measure in eye research involving children 7 to <13 years old.

Change of Visual Acuity Recording Methods in Clinical Studies across the Years

Article

Feb 2008
OPHTHALMOLOGICA

To report any differences in the visual acuity (VA) recording method used in peer-reviewed ophthalmology clinical studies over the past decade. We reviewed the method of assessing and reporting VA in 160 clinical studies from 2 UK and 2 US peer-reviewed journals, published in 1994 and 2004. The method used to assess VA was specified in 62.5% of UK-published and 60% of US-published papers. In the results sections of the UK publications the VA measurements presented were Snellen acuity (n = 58), logMAR acuity (n = 20) and symbol acuity (n = 1). Similarly in the US publications the VA was recorded in the results section using Snellen acuity (n = 60) and logMAR acuity (n = 14). Overall 10% of the authors appeared to convert Snellen acuity measurements to logMAR format. Five studies (3%) chose to express Snellen-type acuities in decimal form, a method which can easily lead to confusion given the increased use of logMAR scoring systems. The authors recommend that to ensure comparable visual results between studies and different study populations it would be useful if clinical scientists worked to standardized VA testing protocols and reported results in a manner consistent with the way in which they are measured.

Clinical experience with the surgical removal of subfoveal neovascular membranes Visual Acuity Assessment with Snellen and ETDRS Charts Trans Am Ophthalmol Soc / 107 / 2009 324 28 Visual acuity changes throughout adulthood in normal, healthy eyes: seeing beyond 6/6

975-976186

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Abrams GW. In discussion of: Berger A, Kaplan HJ. Clinical experience with the surgical removal of subfoveal neovascular membranes. Ophthalmology 1992;99:975-976. Visual Acuity Assessment with Snellen and ETDRS Charts Trans Am Ophthalmol Soc / 107 / 2009 324 28. Elliott DB, Yang KC, Whitaker D. Visual acuity changes throughout adulthood in normal, healthy eyes: seeing beyond 6/6. Optom Vis Sci 1995;72:186-191.

Prospective Evaluation of Visual Acuity Assessment: A Comparison of Snellen Versus ETDRS Charts in Clinical Practice (An AOS Thesis)

Abstract

No full-text available

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Visual Acuity and Fixation Characteristics in Age-Related Macular Degeneration

Scheduled versus Pro Re Nata dosing in the VIEW trials