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ABSTRACT: This study examines the reading performance of patients with age-related macular degeneration (AMD) using 4 readily available fonts.
Experimental study.
Twenty-four patients with bilateral AMD participated.
Reading performance (reading acuity, critical print size, and maximum reading speed) was measured for all patients, using 4 versions of the MNRead charts. These charts were printed in the following fonts: Times New Roman (serif, proportionally spaced), Arial (sans serif, proportionally spaced), Courier (serif, mono spaced), and Andale Mono (sans serif, mono spaced).
Reading acuity was significantly better on the Courier chart (0.58±0.21 logMAR) and significantly worse on the Arial chart (0.69±0.20 logMAR) than on any of the other charts (P<0.05). A larger proportion of patients were able to read≥1 sentences on the Courier chart than on any of the other charts. Reading speed dropped below the limit for fluent reading first with the Arial chart. There was no difference in maximum reading speed with the 4 fonts, and differences in critical print size failed to reach significance (P = 0.052).
Font has an effect on the reading performance of patients with AMD at print sizes close to their reading acuity. Courier was the most advantageous and Arial the worst font for reading smaller print. This is contrary to the advice given by agencies for the blind.
Canadian Journal of Ophthalmology 02/2013; 48(1):56-62. · 1.47 Impact Factor
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ABSTRACT: To explore fixation stability of patients with decreased vision due to idiopathic epiretinal membrane.
Fourteen consecutive patients with unilateral idiopathic epiretinal membrane participated. Visual acuity was measured with ETDRS, and fixation stability was recorded with the MP-1 microperimeter (Nidek Technologies Srl., Vigonza, Italy) for both eyes. Informed consent was obtained from all participants.
Visual acuity of the affected eye (mean = .45 ± .23 LogMAR) was significantly worse than that of the contralateral eye (mean = .11 ± .16 Log-MAR), P < .0001. Fixation stability of the affected eye was not significantly different from that of the contralateral eye. There was a high correlation between fixation stability of the affected and contralateral eyes, r(12) = .67, P = .0087. Moreover, fixation was central or within 3 degrees from the fovea.
Despite lower visual acuity, untreated eyes with idiopathic epiretinal membrane have unimpaired central fixation.
Ophthalmic surgery, lasers & imaging retina. 01/2013; 44(1):46-9.
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ABSTRACT: We investigated whether the sensory impairments of amblyopia are associated with a decrease in eye position stability (PS).
The positions of both eyes were recorded simultaneously in three viewing conditions: binocular, monocular fellow eye viewing (right eye for controls), and monocular amblyopic eye viewing (left eye for controls). For monocular conditions, movements of the covered eye were also recorded (open-loop testing). Bivariate contour ellipses (BCEAs), representing the region over which eye positions were found 68.2% of the time, were calculated and normalized by log transformation.
For controls, there were no differences between eyes. Binocular PS (log(10)BCEA = -0.88) was better than monocular PS (log(10)BCEA = -0.59) indicating binocular summation, and the PS of the viewing eye was better than that of the covered eye (log(10)BCEA = -0.33). For patients, the amblyopic eye exhibited a significant decrease in PS during amblyopic eye (log(10)BCEA = -0.20), fellow eye (log(10)BCEA = 0.0004), and binocular (log(10)BCEA = -0.44) viewing. The PS of the fellow eye depended on viewing condition: it was comparable to controls during binocular (log(10)BCEA = -0.77) and fellow eye viewing (log(10)BCEA = -0.52), but it decreased during amblyopic eye viewing (log(10)BCEA = 0.08). Patients exhibited binocular summation during fellow eye viewing, but not during amblyopic eye viewing. Decrease in PS in patients was mainly due to slow eye drifts.
Deficits in spatiotemporal vision in amblyopia are associated with poor PS. PS of amblyopic and fellow eyes is differentially affected depending on viewing condition.
Investigative ophthalmology & visual science 07/2012; 53(9):5386-94. · 3.43 Impact Factor
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ABSTRACT: The goal of this study was to explore binocular coordination during fixation in patients with age-related macular degeneration (AMD) and to investigate whether there is a shift in eye position when the viewing condition changes from binocular to monocular.
Sixteen people with normal vision and 12 patients with AMD were asked to look at a 3 deg fixation target with both eyes and with each eye individually while the fellow eye was covered by an infrared filter. Fixational eye movements were recorded for both eyes with an EyeLink eye-tracker in all conditions. The shift in eye position at the end of every fixation period was calculated for each eye.
All people with normal vision as well as the majority of patients had good binocular coordination during fixation in the binocular viewing condition. When the viewing condition changed from binocular to monocular, three patients (25%) had atypical shifts in their eye position. The shift was related to (1) loss of fixational control when the better eye was covered and the worse eye viewed the target or (2) a slow drift of the viewing eye that was associated with a large phoria in the covered eye.
Patients with AMD have good binocular ocular motor coordination during fixation. A change in viewing condition from binocular to monocular can lead to disturbances in ocular motor control for some patients, especially in the worse eye.
Optometry and vision science: official publication of the American Academy of Optometry 03/2012; 89(3):277-87. · 1.53 Impact Factor
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ABSTRACT: We studied changes in visual acuity (VA), fixation stability, and location of the preferred retinal locus (PRL) after treatment for unilateral neovascular age-related macular degeneration (AMD) for previously untreated eyes. Concomitant changes in fixation stability, PRL, and VA in the untreated fellow eye were also analyzed.
Pre- and posttreatment tests of visual acuity, fixation stability, and PRL location in both the treated and the untreated eyes were performed on 13 patients undergoing three monthly intravitreal injections of ranibizumab in one eye.
For the treated eyes there were improvements in VA and fixation stability but no changes in the location of the PRL. No significant changes in any of the three variables were found in the untreated eye.
For previously untreated eyes, the improvement in visual acuity after intravitreal ranibizumab injections was accompanied by improvement in fixation stability.
Investigative ophthalmology & visual science 03/2011; 52(7):4208-13. · 3.43 Impact Factor
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ABSTRACT: The authors examined the fixation stability of patients with age-related macular degeneration (AMD) and large interocular acuity differences, testing them in monocular and binocular viewing conditions. The relationship between fixation stability and visual performance during monocular and binocular viewing was also studied.
Twenty patients with AMD participated. Their monocular and binocular distance acuities were measured with the ETDRS charts. Fixation stability of the better and worse eye were recorded monocularly with the MP-1 microperimeter (Nidek Technologies Srl., Vigonza, PD, Italy) and binocularly with an EyeLink eye tracker (SR Research Ltd., Mississauga, Ontario, Canada). Additional recordings of monocular fixations were obtained with the EyeLink in viewing conditions when one eye viewed the target while the fellow eye was covered by an infrared filter so it could not see the target.
Fixation stability of the better eye did not change across viewing conditions. Fixation stability of the worse eye was 84% to 100% better in the binocular condition than in monocular conditions. Fixation stability of the worse eye was significantly larger (P < 0.05) than that of the better eye when recorded monocularly with the MP-1 microperimeter. This difference was dramatically reduced in the binocular condition but remained marginally significant (95% confidence interval, -0.351 to -0.006). For the better eye, there was a moderate relationship between fixation stability and visual acuity, both monocular and binocular, in all conditions in which this eye viewed the target.
Fixational ocular motor control and visual acuity are driven by the better-seeing eye when patients with AMD and large interocular acuity differences perform the tasks binocularly.
Investigative ophthalmology & visual science 11/2010; 52(3):1887-93. · 3.43 Impact Factor
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ABSTRACT: The aim of this study was to explore the plasticity of fixation in patients with central vision loss. Most of these patients use preferred retinal loci (PRLs) in the healthy eccentric part of the retina to fixate, but fixation stability and retinal location are not always optimal for best visual performance. This study examined whether fixation stability and a new PRL location can be trained and whether these changes in ocular motor control transfer into better reading performance. Six patients with age-related macular degeneration participated in the study. Fixation stability measurements, microperimetry, and auditory biofeedback training were performed with the MP-1 microperimeter. The auditory biofeedback was used during five 1-h long training sessions to improve fixation and relocate the PRL. Fixation location and stability were recorded while viewing four different targets: a cross, a letter, a word, and a nine-cycle radial grating. Visual acuity was assessed with the Early Treatment Diabetic Retinopathy Study (ETDRS) chart and reading performance with the MNRead test. The results showed that all patients developed a new PRL in an optimal location for reading, and they were able to use it consistently while viewing different targets. Fixation stability improved 53% after training. Learning transferred to the old PRL even though fixation stability at this location was not trained. All these improvements in ocular motor control translated into better reading performance: reading speed improved 38% and reading acuity and critical print size gained two lines. We conclude that the ability of the ocular motor system to fixate is flexible in patients with central vision loss: a new PRL can be trained, fixation stability can be improved, and learning transfers to an untrained location. These gains in ocular motor control result in better visual performance. This property can be successfully used to optimize the residual vision of patients with central vision loss.
Visual Neuroscience 12/2009; 26(5-6):487-94. · 2.23 Impact Factor
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ABSTRACT: This study examined whether changes in fixation stability and fixation location are good predictors of visual acuity after successful macular hole surgery.
Ten patients with macular hole were tested before surgery and at 1 and 3 months after surgery. Visual acuity was measured with the ETDRS; fixation stability and fixation location were assessed with the MP-1 Microperimeter (Nidek Technologies Srl., Vigonza, PD, Italy). The quantitative measure of fixation stability was calculated with a bivariate contour ellipse area (BCEA). Fixation location shift was evaluated using the differential map analysis feature of the MP-1 Microperimeter.
There was a significant improvement in visual acuity after macular hole closure. Fixation location shifted an average of 0.55 deg and 0.87 deg at 1 month and 3 months after surgery, respectively. The fixation shift was not a good predictor of visual outcome. Fixation stability improved from an average of 0.35 deg(2) before surgery to 0.29 deg(2) at 3 months after surgery. The change in fixation stability (DeltaBCEA = BCEA before - BCEA after surgery) correlated highly with visual outcome. The regression model showed that DeltaBCEA accounted for a significant proportion of the variance in visual acuity both 1 and 3 months after surgery.
Some changes in ocular motor function explain the visual outcome after the anatomic success of macular hole surgery. Fixation location shift has no influence on visual acuity post-operatively; however, change in fixation stability is a strong predictor of visual outcome after successful closure of the macular hole.
Investigative ophthalmology & visual science 09/2008; 50(1):84-9. · 3.43 Impact Factor
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ABSTRACT: The contribution of peripheral vision in inducing self-motion (vection) was investigated in people with bilateral age-related macular degeneration (AMD).
Eleven patients with bilateral AMD and dense central scotomas with no islands of functional central retina and 12 age-matched control subjects were exposed to random-dot patterns projected on a large screen. The dots either moved from left to right, inducing linear vection, or rotated about the roll axis, inducing roll vection. Latency, total vection time, and objective and subjective measures of tilt were recorded.
The patients with AMD experienced shorter latencies than did the age-matched control participants, but the total vection time in both conditions and tilt during roll vection were the same in both groups. There was a positive correlation between objective tilt and subjective measures of tilt in the AMD, but not in the age-matched control group. There was a negative relationship between absolute scotoma size and latency.
Two main conclusions were drawn. First, the role of peripheral vision in inducing vection is enhanced in people with bilateral central vision loss. Second, people with bilateral AMD adapt successfully to a moving environment (they do not experience vection longer, nor do they tilt more) and are more aware of their postural position than are age-matched control subjects.
Investigative ophthalmology & visual science 08/2008; 49(7):3253-8. · 3.43 Impact Factor
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ABSTRACT: The authors examined the fixation stability patterns of people with age-related macular degeneration (AMD) using the MP-1 microperimeter and describe a method to bypass some calibration artifacts that can influence the fixation results.
The preferred retinal locus (PRL) and fixation patterns of 37 eyes with AMD and the fovea's location relative to the middle of the optic disc of 10 experienced controls were measured. For the patients, fixation characteristics such as the former fovea's location, PRL distance, and fixation stability were analyzed.
For the controls, the mean foveal distance temporal to the middle of the optic disc was 15.5 deg +/- 0.86 deg horizontally and -1.33 deg +/- 0.71 deg vertically. Thirty-one out of 37 PRLs occurred in the upper and right quadrants of the retina. There were significant positive correlations between fixation stability and PRL distance from the former fovea. Time since diagnosis and acuity also showed positive correlations with fixation stability and PRL distance from the fovea.
The authors recommend that fixation stability recorded with the MP-1 be analyzed based on the raw data. Most of the fixation parameters obtained agree with those reported in the literature, if proper calibration is used.
Retina 02/2008; 28(1):125-33. · 2.81 Impact Factor
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ABSTRACT: The authors present a computer-based method for evaluating the visual acuity of patients with age-related macular degeneration (AMD). It incorporates four features known to improve visual acuity: high contrast, white optotypes on a black background to reduce intraocular scatter, proportional layout to reduce the effects of crowding, and multiple optotypes to minimize the effects of fixation instability and to maximize the likelihood of optotype detection.
Experiment 1 evaluated the best-eye acuity of 24 patients with AMD using the ETDRS chart and three versions of the Tumbling E acuity test: multiple black optotypes on a white background, single white optotype on a black background, and multiple white optotypes on a black background. Experiment 2 compared the two White E optotype tests with the ETDRS in patients with AMD, and Experiment 3 measured probability summation in persons with normal vision.
Multiple white optotypes on a black background yielded the highest acuity estimates and the ETDRS the lowest. The Single E test yielded a lower estimate of acuity than the two Multiple E tests. The effect of polarity-white on black was better than black on white-was consistent with results found in persons with healthy retinas. For patients with AMD, acuity measured with the Multiple E test was independent of that measured with the ETDRS, but acuity measured with the Single E test decreased as acuity worsened. For the participants with normal vision, the differences between the Multiple and Single E tests were within the known limits of test-retest variability.
The multiple-optotype, reversed-polarity test provides a measure of the optimal visual acuity of which a person is capable and, in this sense, may be a useful tool for assessing rehabilitation progress.
Investigative Ophthalmology & Visual Science 11/2007; 48(10):4838-45. · 3.60 Impact Factor
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ABSTRACT: This study examined two aspects of binocular function in patients with age-related macular degeneration (AMD): summation/inhibition of visual acuity and rivalry. The performance of 17 patients with AMD was compared with that of 17 elderly controls and 21 young people. Monocular and binocular acuities were measured using a multiple-E optotype test. Binocular ratios, defined as the better-eye acuity divided by the binocular acuity, were calculated. We also measured eye dominance during rivalry (proportion of time the participants reported perceiving the input to each eye) and rivalry rates (number of alternations per minute). The results showed that while overall binocular ratios were similar for the three groups, the frequency distributions of people who experienced inhibition, equality or summation were different for the young and AMD groups. In the rivalry test, patients experienced more piecemeal perception than the elderly and young controls, but time dominance from the better-seeing eye was comparable for the three groups. Rivalry rates decreased with age and further with pathology. Moreover, rivalry time dominance of the worse-seeing eye was negatively correlated with interocular acuity differences for the AMD group.
Vision Research 09/2006; 46(16):2487-98. · 2.41 Impact Factor
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ABSTRACT: Normally sighted observers typically benefit from binocular viewing when monocular sensitivities are equivalent. Age-related macular degeneration (AMD) not only destroys the foveal vision, however, but it also affects the 2 eyes unequally, providing grounds for impairment of binocular function. The aim of the present article is to provide a review of the current research on the effect of AMD on binocular vision. The main findings to date reveal that a high proportion of patients show characteristics of binocular contrast inhibition at low and medium spatial frequencies. Yet binocular acuity gain is not different from that of age-matched control participants without AMD. Additional findings show that rivalry processes are severely disrupted in patients with AMD. The effects of the disease on other binocular functions have yet to be explored. Knowledge of binocular function in AMD may one day help clinicians decide on the most appropriate management and rehabilitation techniques.
Canadian Journal of Ophthalmology 07/2006; 41(3):327-32. · 1.47 Impact Factor
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ABSTRACT: The effects of stimulus eccentricity, visual angle, and fixation on linear vection (sensation of self-translation induced by large moving scenes) were examined in healthy young people. Three aspects of vection were measured: latency, total vection time, and strength. The results showed that when peripheral and central stimuli are equal in area, they induce similar vection, but only when they are presented with a fixation cross. When presented without a fixation cross, peripheral stimuli are more effective in inducing vection than central stimuli. In addition, central stimuli with a fixation cross elicited more vection than central stimuli without a fixation cross. Fixation had no influence on the vection induced by peripheral stimuli. These findings indicate that statements about the role of central and peripheral stimuli of equal area in inducing vection should be made only in conjunction with reports about whether these stimuli are presented with or without fixation.
Journal of Vestibular Research 02/2006; 16(6):265-72. · 1.35 Impact Factor
