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Abstract
To examine the effects of pupil dilatation on driving performance and determine whether this was related to changes in standard measures of visual function.
The driving and vision performance of 16 young, visually normal participants was measured with both normal and dilated pupils. Pupils were dilated with 1% tropicamide. Driving performance was measured under daytime conditions on a closed road circuit that was free of other vehicles and has been used in previous studies of driving performance. Measures included road sign detection and recognition, hazard detection and avoidance, gap perception and negotiation, driving reaction times and time to complete the circuit. Visual performance measures included high contrast visual acuity, Pelli-Robson letter contrast sensitivity, and glare sensitivity.
Pupil dilatation significantly (p<0.05) decreased the ability of participants to recognise low contrast hazards and avoid them, decreased their visual acuity and contrast sensitivity and increased glare sensitivity. The decreases in vision performance were not, however, significantly related to the decrement in driving performance.
Pupil dilatation can impair selected aspects of driving and vision performance and patients should be cautioned about these possible effects.
... In the past, most research was directed at establishing the relationship between vision and driving among individuals with normal vision. Only recently, there have been efforts toward evaluating the driving abilities of individuals with vision impairments (1,(44)(45)(46)(47)(48)(49)(50)(51)(52)(53)(54)(55). ...
... A number of studies have evaluated the consequences of driving with reduced visual acuity produced by cataract or other ocular and neurologic diseases or by artificially degrading vision by means of lenses or translucent devices in persons with normal visual acuity (46,49,50,(53)(54)(55).These studies have mostly been performed retrospectively by reviewing visual acuity status and traffic accidents and convictions in the general population, the elderly, the young, and those with physical or mental impairments. Prospective studies have measured driving performance on a closed road track or in a driving simulator (1,(46)(47)(48)(49)(50)(51)(52)(53)(54)(55). Reductions in visual acuity produce impairments in certain aspects of driving related to specific driving tasks, such as recognition of road signs, road hazards, highway markings, and objects entering the roadway (29). ...
Minimal visual standards for obtaining driving licensure in the United States principally use 2 measures: visual acuity and visual field. Although research studies have established a correlation between performance on these measures and safe driving, the correlations are weak and mostly retrospective. These measures remain in place in screening centers largely because they (especially visual acuity) are practical. A newer test of visual attention, called the useful field of view, may be more predictive of safe driving than the traditional measures, but it has not been widely applied in licensing bureaus.
... Some aspects of daytime driving and visual performance have been observed to be altered following tropicamide administration. 1 However, others studies have shown only limited effects on high-contrast acuity and Pelli-Robson contrast threshold and no significant effects on low-contrast visual acuity and field of vision. [2][3][4] The aims of this study were to determine the effects of pupil dilatation on colour discrimination, and on contrast sensitivity over a wide range of spatial frequencies. ...
... 14 Pupillary dilation can also impair aspects of driving performance, and reduced contrast sensitivity is likely to be a contributing factor to this. 1,4 We believe patients should be warned that even if they satisfy the current legal requirements for driving after tropicamide administration, their vision can still be significantly impaired. The extent to which this affects their safety, and the safety of others, is still to be definitely answered and may vary between individuals. ...
To investigate the effects of tropicamide on chromatic and achromatic contrast sensitivities over the physiological range of spatial frequencies.
A total of 26 healthy volunteers, with a mean age of 32 years, were examined with and without one drop of 1% tropicamide being administered 30 min previously. On each occasion, acuity and pupil diameter were recorded, and chromatic and achromatic contrast sensitivities were examined using the Sussex Grating Machine.
Following tropicamide administration mean pupil diameter increased from 4.1 mm to 7.2 mm (P<0.001), and mean BCVA was reduced by 0.07 LogMar units (P<0.001). Achromatic contrast sensitivity was significantly reduced following tropicamide administration at 2.20 cycles per degree (cpd) (P=0.01), 3.40 cpd (P=0.01), 10 cpd (P=0.04), 17 cpd (P=0.04), and 25 cpd (P<0.01). There was no difference in contrast sensitivity at lower spatial frequencies (0.33 and 0.66 cpd). Chromatic contrast sensitivity was not significantly altered when tested along the red-green and tritan confusion axes.
Achromatic contrast sensitivity is significantly reduced following tropicamide administration at intermediate and high spatial frequencies. No significant changes were seen at low spatial frequencies and in chromatic contrast sensitivities.
... The Diopsys® NOVA™ fixed-luminance flicker flash stimulus is constant and does not adjust for changes in pupil size. While patients would benefit from avoiding risks associated with artificial dilation, such as impaired driving and acute closedangle glaucoma, the intra-patient flicker ERG parameters will change with varying pupil size [22,23]. This is in contrast to RETeval, another mydriasis-free ERG system, which adjusts retinal illumination according to pupil size [24]. ...
Purpose
Diopsys® NOVA™ is a novel full-field electroretinography (ffERG) device that can make rapid measurements of retinal electrophysiologic function. Diagnosys® Espion 2™ is a clinical gold-standard ERG device. This study aimed to investigate whether light-adapted Diopsys® NOVA™ fixed-luminance flicker ffERG magnitude and implicit time (converted from phase) measurements correlate with light-adapted Diagnosys® Espion 2™ flicker ffERG amplitude and implicit time measurements, respectively.
Methods
Twelve patients (22 eyes) with various retinal and uveitic diseases underwent light-adapted Diagnosys® Espion 2™ and Diopsys® NOVA™ fixed-luminance flicker testing. Diopsys® magnitude and implicit time (converted from phase) measurements were compared to Diagnosys® amplitude and implicit time measurements, and a Pearson correlation was used to evaluate any existing correlation. Groups were also compared using generalized estimating equations. Bland–Altman plots were utilized to determine agreement between the comparison groups.
Results
Age of patients ranged from 14 to 87 years. 58% (n = 7/12) of patients were female. A significant, positive correlation (r = 0.880, P < 0.001) was observed between magnitude (Diopsys®) and amplitude (Diagnosys®) measurements. Amplitude increases by 6.69 µV for each 1 µV increase in Magnitude (p-value < 0.001). A statistically significant, strong positive correlation was observed between Diopsys® implicit time measurements (converted from phase) and Diagnosys® implicit time measurements (r = 0.814, p-value < 0.001). For each 1 ms increase in Diopsys® implicit time, Diagnosys® implicit time increases by 1.13 ms (p-value < 0.001).
Conclusions
There is a statistically significant positive correlation between light-adapted Diopsys® NOVA™ fixed-luminance flicker amplitude and Diagnosys® flicker magnitude values. Additionally, there is a statistically significant positive correlation between Diopsys® NOVA™ fixed-luminance flicker implicit time (converted from phase) and Diagnosys® flicker implicit time values. These results imply that the Diopsys® NOVA™ module, which utilizes the nonstandard shortened International Society for Clinical Electrophysiology of Vision (ISCEV) ERG protocol, can produce reliable light-adapted flicker ffERG measurements.
... People who are photosensitive are also more prone to blinking during photography, which can introduce blink artefacts, such as eyelashes, that obscure the captured image [16]. Mydriasis can provide discomfort, increase examination time, and prevent people from driving for some time post-application [17,18]. Although not observed in this study's participants, there is a small risk for mydriasis-induced acute angle-closure glaucoma, especially in ethnically susceptible populations such as Asians due to differing ocular anatomy [19]. ...
Aims:
Endothelial dysfunction is an early risk marker of cardiovascular disease in diabetes mellitus. Timely screening is important in reducing cardiovascular disease-associated morbidity and mortality. This cross-sectional study investigates the acceptability and preferability of non-invasive cardiovascular risk procedures (EndoPAT2000 system and the ECG-gated fundoscope) in participants with diabetes mellitus compared to controls.
Methods:
A self-administered Likert scale-based questionnaire was completed by 106 controls and 117 participants with diabetes mellitus, identified through stratified random sampling, upon conclusion of an Australian Heart Eye sub-study conducted at Westmead Hospital, NSW, Australia from 2012 to 2014. Pearson's χ 2 test, independent-samples t-test and regression analysis were performed.
Results:
Study participants who responded to the questionnaire had no preference for procedures (controls: 2.4 ± 1.1 vs diabetes mellitus: 2.5 ± 0.9, p = 0.38) but had an overall more negative experience with most aspects of the ECG-gated fundoscope than the EndoPAT2000 system. Of those with diabetes mellitus, participants who provided poorer self-rated health expressed discomfort with the mydriatic drops (ß 0.27, 95%CI 0.001 - 0.54, p = 0.049) and the fundoscope's green light filter (ß 0.27, 95%CI 0.07 - 0.47, p = 0.009), as well as maintaining still (ß 0.40, 95%CI 0.08 - 0.72, p = 0.02) and not blinking (ß 0.38, 95%CI 0.07 - 0.70, p = 0.02) during photo acquisition. These participants were also less willing to repeat the ECG-gated fundoscope procedure (ß 0.29, 95%CI 0.07 - 0.52, p = 0.01).
Conclusions:
Participants with diabetes mellitus, especially with poorer self-rated health, had a more negative experience with the ECG-gated fundoscope than the EndoPAT2000 system. Difficulties experienced under examination by the ECG-gated fundoscope appear related to the procedural design, which requires amendments improving patient comfort and compliance.
... The study examined the changes in the size of the human pupil showing a correlation with eye workload and supported the use of pupillometry as an efficient tool for distraction study. Several other studies have used the rate of pupil area change while studying workload of drivers in driving tasks [27][28][29]. ...
Distractions external to a vehicle contribute to visual attention diversion that may cause traffic accidents. As a low-cost and efficient advertising solution, billboards are widely installed on side of the road, especially the motorway. However, the effect of billboards on driver distraction, eye gaze, and cognition has not been fully investigated. This study utilises a customised driving simulator and synchronised electroencephalography (EEG) and eye tracking system to investigate the cognitive processes relating to the processing of driver visual information. A distinction is made between eye gaze fixations relating to stimuli that assist driving and others that may be a source of distraction. The study compares the driver’s cognitive responses to fixations on billboards with fixations on the vehicle dashboard. The measured eye-fixation related potential (EFRP) shows that the P1 components are similar; however, the subsequent N1 and P2 components differ. In addition, an EEG motor response is observed when the driver makes an adjustment of driving speed when prompted by speed limit signs. The experimental results demonstrate that the proposed measurement system is a valid tool in assessing driver cognition and suggests the cognitive level of engagement to the billboard is likely to be a precursor to driver distraction. The experimental results are compared with the human information processing model found in the literature.
... Hunters must differentiate between background (and foreground) matter, particularly trees and a variety of flora, and the deer they hunt in ever-changing light levels typical of a woodland or bush environment. The hunter's eyes will accommodate for decreased light (pupil dilation), which has been shown to impair selected tasks and visual performance, albeit in a driving paradigm (Wood, Garth, Grounds, McKay, & Mulvahil, 2003). It should also be noted that pupil dilation can be a product of noradrenaline released from the locus coeruleus and this is associated with emotional and psychological arousal (Privitera, Renninger, Carney, Klein, & Aguilar, 2010); the physiology is introduced later in this chapter. ...
This thesis investigates the behavioural, cognitive, and psychophysiological predictors of failure-to-identify hunting incidents. Approximately twice per year, recreational hunters fatally or severely injure other hunters due to mistaking them for a deer (Green, 2003). The judicial consequence is the charge of ‘careless use of a firearm’, and organisations send an announcement to various media agencies to ‘always identify your target’. Police statements indicate that the shooter is almost always 100% certain that they have identified their target. Shooters testify about the time they took to watch their target, the anatomical parts of the deer they saw, and how they were feeling at the time. However, misidentifications still occur even when no deer are expected (Radio New Zealand, 2016), challenging the potential for cognitive bias to be a significant causal factor, as outlined in a seminal report into failure-to-identify (Wilson & Bridges, 2015). This thesis presents six pieces of research, utilising qualitative and quantitative research methodologies. A FRAM methodology produced a visual depiction of the process of deer hunting, how dynamic hunting is, and how easy it is for unexpected variability to cascade into a misidentification. Three experiments were then conducted over three years validating simulation as an immersive tool and measuring behavioural, cognitive, and psychophysiological responses to a variety of stimuli. The experiments produced revealing and, in some cases, concerning data, with hunters choosing to shoot obscured animals. The participants for all three experiments provided personality data that revealed no apparent association with failure-to-identify behaviour, thereby challenging the hunting community’s belief that it takes a certain ilk to make such a mistake. This thesis concludes with a review of the validity of publicly available statistics of failure-to-identify causation (Mountain Safety Council [MSC], 2017) and a final inspection and calibration of the initially created Hunting FRAM. The findings of this thesis indicate that there are many contributing factors for the emergence of failing to identify one’s target, and hunters are not immune regardless of their age or experience. The thesis concludes with a model for safety trainers to apply to make hunters aware of the dangers of target misidentification.
... Dapiprazole hydrochloride ophthalmic solution 0.5%, an alpha-1 adrenergic receptor antagonist, was approved by the US FDA in 1990 for the treatment of iatrogenically induced mydriasis produced by adrenergic or parasympatholytic agents. 38 However, the product was withdrawn and discontinued by the manufacturer for reasons not related to safety or efficacy. 39 Thymoxamine, another alpha-1 antagonist, has also shown efficacy in reducing PD from iatrogenic mydriasis but was never approved by the FDA for this purpose. ...
Purpose:
Phentolamine mesylate ophthalmic solution (PMOS), applied to the eye topically, was shown previously to have beneficial effects in patients with dim light vision disturbances (DLD), including decreased pupil diameter (PD), improved best-corrected distance visual acuity (BCDVA), as well as lower intraocular pressure (IOP). The ORION-1 trial evaluated the long-term safety and efficacy of PMOS in a glaucomatous, presbyopic population.
Patients and methods:
In this randomized, double-masked, multi-center, placebo-controlled, multiple-dose Phase 2b trial, 39 patients with elevated IOP were randomized to receive one evening dose of study medication or placebo for 14 days. The primary outcome measure was mean change in diurnal IOP, and the key secondary outcome measures included changes in PD, distance-corrected near visual acuity (DCNVA), and conjunctival hyperemia.
Results:
Use of 1% PMOS did not lead to a statistically significant decrease in diurnal IOP compared to placebo (P = 0.89) but trended toward a greater decrease in patients with lower IOP baselines. PMOS produced a statistically significant mean 20% PD reduction under both photopic and mesopic conditions that was sustained for 36 hours post-dosing. A statistically significant number of patients with PMOS compared to placebo demonstrated ≥1 line of improvement in photopic DCNVA at day 8 (P = 0.0018), day 15 (P = 0.0072), and day 16 (P = 0.0163), with a trend for 2- and 3-line improvements at all time points. There was no statistical difference in conjunctival hyperemia compared to placebo.
Conclusion:
Although mean IOP was not lowered significantly, daily evening dosing of 1% PMOS was found to be well tolerated with no daytime conjunctival redness and demonstrated improvement in DCNVA with sustained PD reduction in a glaucomatous and presbyopic population. Smaller pupil size can have beneficial effects in improving symptoms of presbyopia and DLD, which will be the focus of further studies.
... Nevertheless, Table 3 demonstrates that the inter-subject variability is equivalent between a natural pupil Troland test and a dilated constant luminance test. Thus, a Troland test minimizes residuals risks associated with artificial mydriasis, which includes acute closed-angle glaucoma [25] and impaired driving [26], while providing equivalent inter-subject variability. A limitation of this study is we measured the flicker ERG with only one Troland stimulus, and therefore, any dependencies of ERG parameters on retinal illumination Pupil Diameter / mm Fundamental Amplitude Ratio Fig. 6 Relative dependence of implicit times (top plots) and amplitudes (middle and bottom plots) on pupil size. ...
PurposeTo compare the effect of variable pupil size on the flicker electroretinogram (ERG) between a stimulus having constant luminance and a stimulus having constant retinal illuminance (constant Troland) that compensates for pupil size. Methods
Subjects (n = 18) were tested with 12 pairs of the stimuli. The stimulus pair consisted of the ISCEV standard constant luminance stimulus (3 cd·s/m2 with a 30 cd/m2 background) and a constant retinal illuminance stimulus (32 Td·s with a 320 Td background) selected to provide the same stimulus and background when the pupil diameter is 3.7 mm. Half the subjects were artificially dilated, and their response was measured before and during the dilation. The natural pupil group was used to assess intra- and inter-subject variability. The artificially dilated group was used to measure the flicker ERG’s dependence on pupil size. ResultsWith natural pupils, intra-subject variability was lower with the constant Troland stimulus, while inter-subject variability was similar between stimuli. During pupil dilation, the constant Troland stimulus did not have a dependence on pupil size up to 6.3 mm and had slightly larger amplitudes with longer implicit times for fully dilated pupils. For the constant luminance stimulus, waveform amplitudes varied by 22% per mm change in pupil diameter, or by 48% over the 2.2 mm diameter range measured in dilated pupil size. There was no difference in inter-subject variability between constant Troland natural pupils and the same subjects with a constant luminance stimulus when dilated (i.e., the ISCEV standard condition). Conclusions
These results suggest that a constant Troland flicker ERG test with natural pupils may be advantageous in clinical testing. Because of its insensitivity to pupil size, constant Troland stimuli should produce smaller reference ranges, which in turn should improve the sensitivity for detection of abnormalities and for monitoring changes. In addition, the test can be administered more efficiently as it does not require artificial dilation. Clinical Trial registration number This trial is registered at ClinicalTrials.gov (NCT02466607).
... Binocular pupil dilation has been shown to affect drivers' ability to recognise and avoid low contrast hazards and also decreases visual acuity and contrast sensitivity. 10 However, there have been no studies that have investigated the effects of monocular pupil dilation on driving performance. In addition, there appear to be no published studies on the frequency of monocular dilation for fundus examination. ...
Purpose:
The Enright phenomenon describes the distortion in speed perception experienced by an observer looking sideways from a moving vehicle when viewing with interocular differences in retinal image brightness, usually induced by neutral density filters. We investigated whether the Enright phenomenon could be induced with monocular pupil dilation using tropicamide.
Methods:
We tested 17 visually normal young adults on a closed road driving circuit. Participants were asked to travel at Goal Speeds of 40km/h and 60km/h while looking sideways from the vehicle with: (i) both eyes with undilated pupils; (ii) both eyes with dilated pupils; (iii) with the leading eye only dilated; and (iv) the trailing eye only dilated. For each condition we recorded actual driving speed.
Results:
With the pupil of the leading eye dilated participants drove significantly faster (by an average of 3.8km/h) than with both eyes dilated (p=0.02); with the trailing eye dilated participants drove significantly slower (by an average of 3.2km/h) than with both eyes dilated (p<0.001). The speed, with the leading eye dilated, was faster by an average of 7km/h than with the trailing eye dilated (p<0.001). There was no significant difference between driving speeds when viewing with both eyes either dilated or undilated (p=0.322).
Conclusions:
Our results are the first to show a measurable change in driving behaviour following monocular pupil dilation and support predictions based on the Enright phenomenon.
... Besides acting as a marker for cannabis intake, pupil dilation influences safe driving. Dilated pupils can interfere with certain aspects of driving and vision performance (e.g., trouble seeing in light that is too bright), resulting in impaired daytime driving even without the presence of an impairing drug such as cannabis (Battistella et al., 2013;Wood et al., 2003). These negative effects would be further compounded by the psychomotor and cognitive effects of cannabis (Hartman and Huestis, 2013). ...
Background:
The Drug Evaluation and Classification Program (DECP) is commonly utilized in driving under the influence (DUI) cases to help determine category(ies) of impairing drug(s) present in drivers. Cannabis, one of the categories, is associated with approximately doubled crash risk. Our objective was to determine the most reliable DECP metrics for identifying cannabis-driving impairment.
Methods:
We evaluated 302 toxicologically-confirmed (blood Δ(9)-tetrahydrocannabinol [THC] ≥1μg/L) cannabis-only DECP cases, wherein examiners successfully identified cannabis, compared to normative data (302 non-impaired individuals). Physiological measures, pupil size/light reaction, and performance on psychophysical tests (one leg stand [OLS], walk and turn [WAT], finger to nose [FTN], Modified Romberg Balance [MRB]) were included.
Results:
Cases significantly differed from controls (p<0.05) in pulse (increased), systolic blood pressure (elevated), and pupil size (dilated). Blood collection time after arrest significantly decreased THC concentrations; no significant differences were detected between cases with blood THC <5μg/L versus ≥5μg/L. The FTN best predicted cannabis impairment (sensitivity, specificity, positive/negative predictive value, and efficiency ≥87.1%) utilizing ≥3 misses as the deciding criterion; MRB eyelid tremors produced ≥86.1% for all diagnostic characteristics. Other strong indicators included OLS sway, ≥2 WAT clues, and pupil rebound dilation. Requiring ≥2/4 of: ≥3 FTN misses, MRB eyelid tremors, ≥2 OLS clues, and/or ≥2 WAT clues produced the best results (all characteristics ≥96.7%).
Conclusions:
Blood specimens should be collected as early as possible. The frequently-debated 5μg/L blood THC per se cutoff showed limited relevance. Combined observations on psychophysical and eye exams produced the best cannabis-impairment indicators.
... Mydriasis using tropicamide 1% can interfere with the patient's lifestyle by reducing visual acuity and decreasing their amplitude of accommodation, restricting driving and the return to employment. [9][10][11][12] This may discourage attendance for the screening visit particularly in the younger age group who are more at risk for non-attendance. 13 A recent study found that many return to work and drive immediately after the appointment and the introduction of the routine use of drops may discourage attendance. ...
Purpose To examine factors necessitating pupil dilation to achieve gradable diabetic screening photographs using a digital non-mydriatic camera and to establish techniques to predict the need for dilation and to validate them. Methods Prospective clinic-based cross-sectional study with follow-up validation study. The participants' involved consecutive patients attending the diabetic retinopathy screening clinic at a University Hospital. Best corrected visual acuity, age, sex, pupil size, mean spherical equivalent, cataract grade and the requirement for dilation to achieve gradable photographs in 90 patients were recorded. Data analysis using principal component analysis and multivariate analysis of variance derived a set of equations to predict the requirement for dilation. The predictive powers of these equations were validated in an independent group of 51 patients. Results Smaller pupil size, denser nuclear colour, older age, poorer best-corrected visual acuity, cortical lens opacity and posterior subcapsular lens opacity were associated with the need for dilation (Po0.001 in all). Single variables used in isolation had a poorer predictive value than combining variables. Dilating patients with either a pupil size 43.75 mm or age 459 years correctly allocates 83 and 78% of patients, respectively to dilation or not. Combining pupil size with age produces a decision table that improves the predictive value to 84%. In the validation study this table had a predictive value of 80%. Conclusion We have produced and validated criteria based on a range of clinical variables for application in a clinical setting that allows for the development of targeted mydriasis.
... ial. [35] Anticholinergics These drugs are as well prone to have their CNS side effects which can impair driving performance includes confusion, blurred vision, dizziness and drossiness. [36] Pupil dilation due to anticholinergic drugs can impair selected aspects of driving and vision performance, patient should be caution about these side effects. [37] In a study it was found that driver taking These drugs are less likely to affect driving but some of them can produce dizziness or other undesirable CNS effects. Fluroquinolones are associated with some CNS side effects like dizziness, convulsion, psychosis, and insomnia. Among the fluroquinolones currently available levofloxacine, oflo ...
There are number of drugs in our community both as OTC as well as prescription which can influence the driving performance. Relevant literature was identified through searches in Medline and Google scholar. The current stage of knowledge regarding effect of commonly used drugs on driving behavior is reviewed and discussed. There are large numbers of drugs which can influence driving performance, among them drug acting on CNS are more common. Elderly people are more susceptible for this effect. Theoretical consideration and empirical observation suggest that higher doses may impede performance.There are conspicuous lacks of data on all the drugs and more studies are required to corroborate the influence of drugs on driving performance.
... Mydriasis using tropicamide 1% can interfere with the patient's lifestyle by reducing visual acuity and decreasing their amplitude of accommodation, restricting driving and the return to employment. [9][10][11][12] This may discourage attendance for the screening visit particularly in the younger age group who are more at risk for non-attendance. 13 A recent study found that many return to work and drive immediately after the appointment and the introduction of the routine use of drops may discourage attendance. ...
To examine factors necessitating pupil dilation to achieve gradable diabetic screening photographs using a digital non-mydriatic camera and to establish techniques to predict the need for dilation and to validate them.
Prospective clinic-based cross-sectional study with follow-up validation study. The participants' involved consecutive patients attending the diabetic retinopathy screening clinic at a University Hospital. Best corrected visual acuity, age, sex, pupil size, mean spherical equivalent, cataract grade and the requirement for dilation to achieve gradable photographs in 90 patients were recorded. Data analysis using principal component analysis and multivariate analysis of variance derived a set of equations to predict the requirement for dilation. The predictive powers of these equations were validated in an independent group of 51 patients.
Smaller pupil size, denser nuclear colour, older age, poorer best-corrected visual acuity, cortical lens opacity and posterior subcapsular lens opacity were associated with the need for dilation (P<0.001 in all). Single variables used in isolation had a poorer predictive value than combining variables. Dilating patients with either a pupil size>3.75 mm or age>59 years correctly allocates 83 and 78% of patients, respectively to dilation or not. Combining pupil size with age produces a decision table that improves the predictive value to 84%. In the validation study this table had a predictive value of 80%.
We have produced and validated criteria based on a range of clinical variables for application in a clinical setting that allows for the development of targeted mydriasis.
... Each participant completed a practice run performed in the direction opposite to the recorded run. The driving assessment was selected to provide a relatively high degree of complexity, involving tasks of recognition, divided attention, gap perception, speed and manoeuvring, and has been described in detail by Wood et al. 16 The outcome measures included sign recognition, road hazard recognition and road hazard avoidance, correct gap judgements, divided attention, manoeuvring time and time to complete the course. ...
Cataract surgery is one of the most common medical procedures undertaken worldwide.
To investigate whether cataract surgery can improve driving performance and whether this can be predicted by changes in visual function.
29 older patients with bilateral cataracts and 18 controls with normal vision were tested. All were licensed drivers. Driving and vision performance were measured before cataract surgery and after second eye surgery for the patients with cataract and on two separate occasions for the controls. Driving performance was assessed on a closed-road circuit. Visual acuity, contrast sensitivity, glare sensitivity and kinetic visual fields were measured at each test session.
Patients with cataract had significantly poorer (p<0.05) driving performance at the first visit than the controls for a range of measures of driving performance, which significantly improved to the level of the controls after extraction of both cataracts. The change in contrast sensitivity after surgery was the best predictor of the improvements in driving performance in patients with cataract.
Cataract surgery results in marked improvements in driving performance, which are related to concurrent improvements in contrast sensitivity.
Clinical relevance:
Binocular visual acuity is an important index of functional performance. Optometrists need to know how binocular visual acuity is affected by aniseikonia, and whether reduced binocular visual acuity is a marker for aniseikonia.
Background:
Aniseikonia, the perception of unequal image sizes between the eyes, can occur spontaneously or can be induced after different types of eye surgery, or trauma. It is known to affect binocular vision, but there are no prior studies about how it affects visual acuity.
Methods:
Visual acuity was measured for 10 healthy well-corrected participants aged 18-21 years of age. Aniseikonia of up to 20% was induced in one of two ways: (1) size lenses, which provided minification of field of view in one eye of each participant and (2) polaroid filters, which allowed vectographic viewing of optotypes on a 3D computer monitor. The best corrected acuity was measured on conventional logarithmic progression format vision charts and isolated optotypes, under both induced aniseikonia conditions.
Results:
Induced aniseikonia caused binocular visual acuity thresholds to increase by small but statistically significant amounts, with the largest deficit being 0.06 logMAR for 20% size differences between the eyes. Binocular visual acuity was worse than monocular visual acuity for aniseikonia of 9% and greater. Acuity measured with the vectographic presentation gave slightly higher thresholds (by 0.01 logMAR) than for those viewed with size lenses. Acuity measured with charts gave slightly higher thresholds (by 0.02 logMAR) than with isolated letters.
Conclusion:
An acuity change of 0.06 logMAR is small and may be missed in a clinical examination. Therefore, visual acuity cannot be used as a marker of aniseikonia in clinical settings. Even with very marked induced aniseikonia, binocular visual acuity remained well within standards for licen*c*sing of drivers.
Purpose:
To determine the factors affecting the shift of refraction after trabeculectomy.
Material and methods:
The study included 42 patients who were examined prior to trabeculectomy and at the following timepoints: 1 week, 1 month and 3 months after surgery. Examination included tonometry with assessment of corneal biomechanical properties, keratorefractometry with vector analysis, and biometry. The obtained data was processed for regression analysis and to find the possible correlations.
Results:
All significant correlations between the measured parameters only occur on week 1. Postoperative spherical component of refraction (sphere) correlates negatively both with preoperative axial length (AL) and anterior chamber depth (ACD) (r=-0.699 and r=-0.458, p<0.05) and postoperative AL and ACD (r= -0.767 and r= -0.415, p<0.011). Dependence of sphere on AL is also expressed as a regression model. The magnitude of AL change depends on the magnitude of intraocular pressure (IOP) change (r=0.729, p<0.0001) and correlates negatively with postoperative IOP (r=-0.454, p=0.009) and baseline corneal hysteresis (CH; r= -0.482, p=0.009). Dependence of AL on IOP is also expressed as a regression model. The magnitudes of sphere and cylinder shifts correlate negatively with each other (r=-0.416, p=0.038). Keratometry reveals that the overall cylinder value correlates with the corneal cylinder, and so do the magnitudes of their shifts (r=0.589 and r=0.574, p<0.0001). Dependence of corneal hysteresis on IOP is expressed as a regression model; however, neither tonometric nor biomechanical corneal properties correlate with refraction.
Conclusions:
Sphere correlates negatively with AL and ACD. In turn, AL is related to the reduction in IOP. This dependence is likely the most important one for the refraction shift after trabeculectomy. No correlations were found for the change of astigmatism.
Significance:
After a dilated eye examination, many patients experience symptoms of prolonged light sensitivity, blurred vision, and cycloplegia associated with pharmacological mydriasis. Phentolamine mesylate ophthalmic solution (PMOS) may expedite the reversal of mydriasis in patients, potentially facilitating return to functional vision and reducing barriers to obtaining dilated eye examinations.
Purpose:
The protracted reversal time after pharmacologically induced pupil dilation impairs vision. We tested the hypothesis that PMOS rapidly reduces pupil diameter in this acute indication.
Methods:
In this double-masked placebo-controlled, randomized, two-arm crossover phase 2b trial, we evaluated the effects of one drop of 1% PMOS applied bilaterally in subjects who had their pupils dilated by one of two common mydriatic agents: 2.5% phenylephrine or 1% tropicamide. End points included change in pupil diameter, percent of subjects returning to baseline pupil diameter, and accommodative function at multiple time points.
Results:
Thirty-one subjects completed the study (15 dilated with phenylephrine and 16 with tropicamide). Change in pupil diameter from baseline at 2 hours after maximal dilation with 1% PMOS was -1.69 mm and was significantly greater in magnitude compared with placebo for every time point beyond 30 minutes (P < .05). At 2 hours, a greater percentage of study eyes given 1% PMOS returned to baseline pupil diameter compared with placebo (29 vs. 13%, P = .03), which was this also seen at 4 hours (P < .001). More subjects treated with PMOS in the tropicamide subgroup had at least one eye returning to baseline accommodative amplitude at 2 hours (63 vs. 38%, P = .01). There were no severe adverse events, with only mild to moderate conjunctival hyperemia that resolved in most patients by 6 hours.
Conclusions:
Phentolamine mesylate ophthalmic solution at 1% reversed medically induced pupil dilation more rapidly than placebo treatment regardless of which mydriatic was used (adrenergic agonists and cholinergic blockers) with a tolerable safety profile.
The popularity and rapid growth of roadside electronic billboards in recent 1 decades has resulted in severe safety issues in China, especially at nighttime. However, 2 in-depth investigation of their impact on driver visual properties has been rather limited. 3 This study intends to bridge this gap and gain insights based on field experiments 4 conducted on road segments of Freeways G60 and G2 in China. Fifty-five participants 5 were recruited to drive along the selected freeway segments. Multiple properties were 6 captured including the eye movement (transitions between regions of interest), glance 7 duration, and the rate of pupil area change. Vehicle behavior parameters, including the 8 standard deviation of lane position and the speed, were also collected in order to 9 estimate the potential risks. Results show that billboards along the freeway result in 10 distraction for drivers which is associated with higher risks. Results further indicate that 11 the random and messy billboard installations along freeways in China, especially at 12 nighttime, have become a safety concern which needs further exploration. 13 14
Résumé
Objectif
Démontrer une baisse d’acuité visuelle (AV) cliniquement significative de loin après instillation de collyres mydriatiques dans un œil atteint de dégénérescence maculaire liée à l’âge (DMLA) exsudative.
Matériel et méthodes
Une étude prospective, d’évaluation de pratique professionnelle, s’est déroulée dans le service d’ophtalmologie du centre hospitalo-universitaire de Tours entre le 19/07/2018 et le 29/08/2018. Des mesures d’AV de loin, sur échelle ETDRS, et de près, sur échelle Parinaud, ont été effectuées avant et après instillation d’une goutte de tropicamide 0,5 % et de phényléphrine 10 % pour les 40 yeux inclus, atteints de DMLA exsudative.
Résultats
La différence moyenne d’AV mesurée de loin entre avant et après DP était de 0,06 LogMAR (SD = 0,14) (p < 0,01), soit −3,05 lettres lues (SD = 7,52) sur échelle ETDRS (p = 0,01). De près, elle était de 0,16 LogMAR (SD = 0,16) (p < 0,001), soit −1,58 paragraphe lu (SD = 1,63) sur échelle Parinaud (p < 0,001).
Discussion
L’absence de baisse d’AV cliniquement significative de loin chez les DMLA exsudatives post-dilatation pupillaire (DP) pourrait s’expliquer par le faible éblouissement de l’échelle ETDRS, une photophobie moindre, des AV pré-DP basses et un équilibre entre aberrations optiques de haut degré et diffraction. Un résultat contraire de près s’expliquerait principalement par l’éblouissement plus important lié à l’éclairage de l’échelle Parinaud.
Conclusion
Notre objectif principal n’a pas été atteint. Une étude postulant une absence de baisse d’AV cliniquement significative de loin post-DP serait nécessaire pour envisager de mesurer directement l’AV post-DP des yeux atteints de DMLA exsudative dans notre pratique quotidienne.
ABSTRACT The popularity and rapid growth of roadside electronic billboards in recent decades has resulted in severe safety issues in China, especially at nighttime. However, in-depth investigation of their impact on driver visual features has been rather limited. This study intends to bridge this gap and gain insights based on field experiments conducted on road segments of Freeways G60 and G2 in China. Fifty-five participants were recruited to drive along the selected freeway segments. Multiple features were captured including the eye movement (transitions between regions of interest), glance duration, and the rate of pupil area change. Vehicle behavior parameters, including the standard deviation of lane position and the speed, were also collected in order to estimate the potential risks. Results show that billboards along the freeway result in distraction for drivers which is associated with higher risks. Results further indicate that the random and messy billboard installations along freeways in China, especially at nighttime have become a safety concern which needs further exploration.
Eye drops can help to diagnose and prevent complications of neurological disorders. Guttae ophthalmicae (eye drops) are generally safe because the drugs rarely achieve significant systemic concentrations, although there are rare exceptions. This article covers contemporary pharmacological pupil testing; how to dilate a pupil safely; common reasons why pupils do not respond to drops; and corneal lubrication to prevent complications of weak eye closure.
The aim of this randomized controlled equivalence trial was to demonstrate that, in diabetic patients, dilating the pupils before as compared with after refraction and visual acuity assessment would not lead to different advice given to patients.
Three hundred sixteen adult patients with diabetes mellitus were randomized. The experimental group was administered tropicamide 0.5% before refraction and visual acuity assessment and the control group after refraction and visual acuity assessment. Study outcomes were the advised time till next visit, the advice on adjustment of refractive correction, further diagnostics, treatment, duration of the eye examination, and patient satisfaction.
No difference was seen in advised time till next visit between the experimental group (12.39 ± 5.01 months) and the control group (12.84 ± 4.96 months) (p = 0.425). In addition, the advice concerning adjustment of refractive correction (p = 0.069), further diagnostics (p = 1.000), and therapy (p = 0.178) did not significantly differ. Waiting time was significantly shorter for the experimental group (22.25 vs. 36.18 minutes; p < 0.001). People in the experimental group were relatively more often "very satisfied" than "satisfied" in comparison with participants in the control group for "attention being paid by the optometrist" (p = 0.025) and "advice on refractive correction" (p = 0.047).
In diabetic patients, dilating pupils before refraction and visual acuity assessment does not lead to different advice given to patients compared with dilating pupils after refraction and visual acuity assessment, whereas waiting time significantly decreases and patient satisfaction is similar or even better. Increased efficiency is beneficial to both patients and clinicians.
The purpose of this study was to determine the vision requirements for licensing and registration examiners (LREs) of motor vehicle drivers in the state of California.
A comprehensive investigation was conducted that included a literature review, consideration of the Americans with Disabilities Act, analysis of materials with a subject matter expert panel, an overview of visual function tests, a formal job analysis, job audits and site visits to licensing offices, analysis of accidents and critical incidents, performance of simulation studies, and a review and evaluation of all materials collected during the study.
Based on this analysis, three visual functions (best-corrected visual acuity, peripheral visual field extent, and color vision) were determined to be important for performing the essential job functions of an LRE. It was recommended that LREs demonstrate a best-corrected visual acuity of at least 20/20 in each eye, a peripheral visual field of at least 100 degrees diameter of horizontal and vertical extent in each eye (with no evidence of scotomas or pathologic areas of nonseeing within the visual field), and color vision capabilities that permit a passing score on the Farnsworth Panel D-15 color vision test.
The findings of this investigation provide a strong basis for specifying and justifying vision requirements for performing essential job functions for an LRE in the state of California.
Dilatation of the pupil (mydriasis) is a core component of a comprehensive ophthalmic examination and is becoming part of the eye examination routine for optometrists in the United Kingdom.1 As many patients drive to attend their examinations, concerns have been raised regarding the effects of pupillary dilatation on driving and whether or not the visual standard for driving is met after dilatation.2–4 Therefore, we investigated the effect of mydriasis on the visual standard for driving a private vehicle in the United Kingdom.
Twenty adult subjects (mean age 24 years) with normal or corrected to normal visual acuity participated in the study. A selection of six different pairs of number plates (black on white and black on yellow), which conformed …
To assess the effects of pupillary dilation on image quality and certitude of screening diabetic retinopathy by trained endocrinologists using a digital nonmydriatic camera.
Prospective, comparative, observational case series.
One hundred fifty patients with diabetes attending a hospital-based photographic screening clinic had five-field (45 degree) digital retinal imaging and mosaic construction, first through dark-adapted pupils, then after a single application of tropicamide 1%. The 600 sets of images (150 patients, 300 eyes, before and after dilation) were graded independently and in a blinded manner by two endocrinologists and two ophthalmologists, with the consensual opinion on dilated images of the latter serving as the gold standard. The criteria of evaluation were assessment of image quality and certitude of detecting and grading retinopathy.
Of 300 eyes, pharmacological mydriasis improved image quality, with an increase in the number of eyes with five good images from seven to 160 and good-quality mosaics from 99 to 233. Dilation allowed better identification of maculopathy in the second eye because there was a decrease in ungradeable central images from 127 to 15 eyes. Dilation increased the number of eyes having retinopathy detected with certainty from 153 to 252 and graded with certainty from 173 to 277. No adverse effects were recorded.
Single application of tropicamide 1% significantly improves image quality and certitude of screening diabetic retinopathy with nonmydriatic camera by endocrinologists.
To compare contrast and glare vision in a prospective study of eyes treated using conventional and wavefront-guided LASIK surgery. The reproducibility of a glaremeter device used to quantitatively measure glare and halo was also determined.
Ninety-two eyes of 46 patients underwent conventional LASIK surgery and 104 eyes of 52 patients underwent wavefront-guided LASIK surgery. Visual acuity, glare disability measured using a glaremeter, and contrast sensitivity assessed using a Pelli-Robson chart were measured monthly for 6 months postoperatively. Glaremeter testing was performed under both mesopic (5.4 +/- 0.4 cd/m2) and photopic (78.3 +/- 4.4 cd/m2) conditions. To evaluate the reproducibility of the glaremeter, 36 eyes of 18 nonoperated myopic patients were tested.
The coefficient of variation and the reliability coefficient for the glare test were 13.6% and 95.2%, respectively. The glaremeter showed that glare disability under mesopic conditions differed between conventional and wavefront-guided LASIK eyes over 6-month follow-up (907.5 +/- 491.5 vs 986.1 +/- 448.0 pixels preoperatively and 1717.1 +/- 521.2 vs 1407.8 +/- 411.3 pixels at 6 months, P<.0001). At 6 months, contrast sensitivity log values were 1.62 +/- 0.31 and 1.78 +/- 0.34 for conventional and wavefront-guided LASIK eyes, respectively (P=.010). The visual complaint score was lower in the wavefront-guided LASIK group (P=.0116).
Compared to conventional ablation, wavefront-guided ablation provided superior outcomes in terms of postoperative glare under mesopic conditions, subjective complaints, and contrast sensitivity. In addition, it appears the glaremeter can be used for clinical quantitative evaluation of glare and halo.
This study was conducted to assess dynamic visual acuity (DVA) under pupil dilation.
Pupil dilation may negatively affect driving performance.
Thirty healthy young adults (mean age 29.4 years) with pupil dilation participated in this study as the Mydrin P group. In addition to them, 15 healthy young adults (mean age 28.5 years) without pupil dilation were enrolled as the control group. DVA was measured binocularly with free-head viewing at 0, 30, 60, 120, and 360 min after mydriatic drop instillation in both eyes. Pupil size was measured at each time.
In the Mydrin P group, DVA significantly improved at 30, 60, and 120 min (ANOVA; p < .01) but returned to the predilation level at 360 min (ANOVA; p = .61). Pupil size changed from 4.1 to 7.8 mm (ANOVA; p < .01) at 30 min after the instillation, and this level was maintained up to 120 min but returned to normal within 360 min. In the control group, DVA did not significantly change at all measured times (ANOVA; p > .9). DVA was significantly (p < .05) correlated with the pupil size at all measured times.
The improvement in DVA was related to the enlargement of the pupil. This study suggests that the pupil size is one factor that may affect DVA.
Potential applications of this study include useful information to assess the effect of pupil dilation on driving performance.
To determine whether there is a clinically significant reduction in visual acuity (VA) or contrast sensitivity (CS), with and without glare, following examination with pupil dilation in patients currently driving.
From November 1, 2004, to February 28, 2005, 105 consecutive patients were assessed in our institution. The better eye was assessed pre- and post-dilation with and without glare administered through the Brightness Acuity Tester. VA was assessed using the Early Treatment in Diabetic Retinopathy Study (ETDRS) and Snellen charts. CS was measured using the Vistech VCTS 6500 Chart.
With no glare, there was a mean reduction of 4.8 letters read from the ETDRS chart following dilation (p < 0.001). With glare, there was a mean reduction of 7.1 letters (p < 0.001). Compared with patients with initial VA of 20/20, patients presenting with a Snellen VA of 20/25 to 20/40 had a 9.75 relative risk of postdilation VA worse than 20/40, whereas patients with initial VA of 20/40 had a 19.8 relative risk of postdilation VA worse than 20/40. With the addition of glare, these relative risks increased to 13.9 and 28.8, respectively. Without glare, there was a significant reduction in CS after dilation at spatial frequencies of 2.0, 4.0, and 6.0 cycles/degree (p = 0.014, p < 0.001, and p < 0.001, respectively). With glare, there was a greater reduction in CS at these 3 spatial frequencies (p < 0.001 for all).
There is a significant reduction in VA and CS after dilation that is further confounded by the effect of glare. This reduction may limit some patients from driving after dilation.
A randomized, within-subject, double-blind, inpatient study of the physiological and subjective effects of oral 3,4-methylenedioxymethamphetamine (MDMA) was conducted in human volunteers with previous MDMA experience. Placebo, low (1.0 mg/kg), and high (1.6 mg/kg) doses of oral MDMA were administered in a controlled inpatient setting at least 7 days apart to 6 African American (4 male, 2 female) and 2 white (both male) volunteers (mean [SE] age, 21.1 [0.8] years; weight, 77.2 [7.7] kg). 3,4-Methylenedioxymethamphetamine doses were 46 to 150 mg, in the range of typical recreational doses. Participants completed all sessions without clinically significant adverse events. 3,4-Methylenedioxymethamphetamine produced significant dose-dependent increases in heart rate (highest, 132 bpm), systolic (highest, 171 mm Hg) and diastolic (highest, 102 mm Hg) blood pressure, and subjective responses for energy level, closeness to others, mind racing, heightened senses, and high (evaluated by visual analog scales). Peak effects occurred 1 to 2 hours after dose, with no secondary peak. There were no significant effects on body temperature (measured at tympanic membrane), respiratory rate, or blood oxygen saturation (by pulse oximetry). Although most physiological and subjective parameters were significantly correlated with MDMA plasma concentrations, correlation coefficients were low and clinically insignificant, eliminating the ability to predict effects from single plasma concentrations. These findings suggest that oral MDMA in typical recreational doses produces short-term effects on cardiovascular function and subjective state but that temperature effects may result from interaction with environmental and subject factors.
We describe a new glare test that uses low contrast letters and a variable surround glare source. The test is easy to administer clinically and all test targets, luminance levels, glare geometry, and viewing conditions are well controlled. We found the most useful index of disability glare to be the difference in visual acuity scores for the low contrast chart in the no-glare and high-glare conditions and refer to this as the disability glare index (DGI). We tested a group of normal subjects who were divided into younger (age 15 to 41 years) and older (age 50 to 82 years) groups. The mean DGI value for the older group (10.2 +/- 4.8) was significantly higher than that for the younger group (2.3 +/- 1.9). The DGI is a better discriminator between the two groups than either high or low contrast visual acuity. We attribute the significantly higher DGI values in the older group to increased intraocular light scatter. We find DGI is poorly correlated with high contrast visual acuity (r = 0.33). Our findings suggest that this test of disability glare is sensitive to relatively modest changes in the ocular media. It is a potentially useful tool in detection and assessment of subtle media disturbances and in monitoring changes in the ocular media over a period of time.
To document the experience of patients driving after drops to dilate the pupils. There are no documented guidelines on driving after pupillary dilatation. This is a study of patients who drove a car after attending the eye casualty for an ocular examination during which their pupils were dilated.
Thirty patients were identified who felt confident to drive after their pupils were dilated. Distant visual acuities, colour vision and confrontation visual fields were assessed before and after pupillary dilatation with 2.5% phenylephrine and 1% tropicamide. These patients met the legal requirements for driving after pupillary dilatation. The patients completed a questionnaire that recorded their subjective experiences of driving while their pupils were dilated.
The mean age of the patients was 51.9 +/- 19.7 years (range 20-73 years). Twenty-seven of the 30 patients undertook the journey on familiar roads, and 14 of 30 wore spectacles. The mean spherical equivalent was +2.00 dioptre sphere for distance and a mean additional spherical equivalent of 1.75 dioptre sphere for near. Twenty patients experienced glare, which was severe enough to cause difficulty driving in three cases. Two of these patients drove in sunny weather conditions and one in light (not sunny) weather. Six patients had difficulty with road signs, two had difficulty judging distances and one reported difficulty with traffic lights.
Dilating the pupils did not reduce distance visual acuity. However, it would seem appropriate to warn patients of the problems associated with glare and, if driving is their only option for transport home, recommend that they allow sufficient time to adapt to a dilated pupillary state, drive only on familiar roads and avoid driving in sunny weather.
To assess the effect of pupil dilation on vision and driving ability.
A series of tests on various parameters of visual function and driving simulator performance were performed on 12 healthy drivers, before and after pupil dilation using guttae tropicamide 1%. A driving simulator (Transport Research Laboratory) was used to measure reaction time (RT), speed maintenance and steering accuracy. Tests of basic visual function included high- and low-contrast visual acuity (HCVA and LCVA), Pelli-Robson contrast threshold (CT) and Goldmann perimetry (FIELDS). Useful Field of View (UFOV--a test of visual attention) was also undertaken. The mean differences in the pre- and post-dilatation measurements were tested for statistical significance at the 95% level using one-tail paired t-tests.
Pupillary dilation resulted in a statistically significant deterioration in CT and HCVA only. Five of 12 drivers also exhibited deterioration in LCVA, CT and RT. Little evidence emerged for deterioration in FIELDS and UFOV. Also, 7 of 12 drivers appeared to adjust their driving behaviour by reducing their speed on the driving simulator, leading to improved steering accuracy.
Pupillary dilation may lead to a decrease in vision and daylight driving performance in young people. A larger study, including a broader spectrum of subjects, is warranted before guidelines can be recommended.
Summary The effects of ß-adrenergic receptor antagonists on psychometric tests including vehicle handling, choice reaction time, and kinetic visual acuity (KVA), are reviewed. The ß-Blockers had little effect on the performance tests, with the unexplained but reproducible effect of enhanced KVA performance with atenolol. Although the ß-Blockers had little effect on performance tests they were shown to have psychotropic effects in normal volunteers. The reasons for the conflicting evidence concerning the effect of these drugs on performance tests is discussed in relation to the present experiments and to variables that may influence response. It is concluded that one should use tests that are as independent as possible from potentially confounding variables. The use of evoked potentials in the electroencephalogram is one such test. A preliminary study is described in which the effects of ß-Blockers were detected using visual evoked responses on the electroencephalogram.
Background: Mydriatic agents are used in optometric practice to dilate the pupil and facilitate the use of techniques, such as binocular indirect ophthalmoscopy to visualise the fundus. While the effects such pharmacological agents have on the size of the pupil are obvious, information regarding the patient's perception of the effects of mydriasis is less well established.
Methods: A survey of patients presenting consecutively to a suburban optometric practice was performed to document the patient's perceptions of pupillary dilation. Results: Most patients reported that mydriasis resulted in blurry vision and increased sensitivity to glare, which interfered with some aspects of their everyday life, notably driving a motor vehicle. However, the majority of patients were prepared to undergo mydriasis at future eye examinations, if required.
Conclusions: Practitioners should not refrain from performing mydriatic fundus examinations simply because of a perceived inconvenience to their patients. Nevertheless, care should be exercised and patients should be informed of the potential for visual disturbances with mydriasis, especially those patients driving a motor vehicle directly after the examination.
Diabetic patients routinely have their pupils dilated for fundoscopy as part of the annual review. To assess the ability of diabetic patients to drive after pupillary dilatation we studied 61 diabetic patients (18 IDDM, 43 NIDDM), mean age 54.98 years, before and 1 h after pupillary dilatation with 1% tropicamide. Binocular visual acuity (BVA) and contrast sensitivity were checked without glare, with glare, and with glare and sunglasses. Glare was introduced using a 60 W bulb in all 61 patients and with a 500 W bulb in 37 of these patients. Prior to dilatation all 61 patients had a BVA of 6/9 or better. A significant reduction in BVA was found post-dilatation (p = 0.005) and 4 out of the 61 patients (6.56%) had a post-dilatation BVA of less than 6/9. The 60 W glare source caused a significant reduction in BVA pre-dilatation (p < 0.05), but not the 500 W glare. With glare, post-dilatation BVA reduced further, resulting in 6 and 7 patients having a BVA of less than 6/9 with the 60 W and 500 W glare source, respectively. The addition of sunglasses with glare did not improve the BVA. No patient with a BVA of 6/5 pre-dilatation reduced to less than 6/9 post-dilatation. No significant change in contrast sensitivity was found in any of the test conditions. We conclude that patients who meet the visual legal requirements to drive (BVA < or = 6/9) prior to dilatation may not fulfil them post-dilatation. This has important clinical implications and the time course of the phenomenon requires exploration. Meanwhile, patients need to be warned not to drive after pupillary dilatation when they attend for annual fundoscopic examination, certainly for at least two hours.
The effects of beta-adrenergic receptor antagonists on psychometric tests including vehicle handling, choice reaction time, and kinetic visual acuity (KVA), are reviewed. The beta-blockers had little effect on the performance tests, with the unexplained but reproducible effect of enhanced KVA performance with atenolol. Although the beta-blockers had little effect on performance tests they were shown to have psychotropic effects in normal volunteers. The reasons for the conflicting evidence concerning the effect of these drugs on performance tests is discussed in relation to the present experiments and to variables that may influence response. It is concluded that one should use tests that are as independent as possible from potentially confounding variables. The use of evoked potentials in the electroencephalogram is one such test. A preliminary study is described in which the effects of beta-blockers were detected using visual evoked responses on the electroencephalogram.
The visual acuity of 100 patients between the ages of 16 and 66 years, seen for routine ophthalmologic examination, was measured before and after dilation. All patients had a predilation visual acuity of 20/40 or better. Postdilation binocular visual acuity using the patients' usual correction was measured first in the office and then outdoors, both with the patient's back to and the patient facing the sun, with and without the aid of postmydriatic sunglasses. Twelve percent experienced disabling photophobia even with the use of postmydriatic sunglasses, with 3% having significant objective visual loss defined as 20/50 or worse. No objective visual loss was found in 30 controls examined outdoors before dilation, without sunglasses. We recommend that patients who have experienced significant photophobia with dilation in the past, or who have never before undergone dilation, make arrangements for transportation after a dilated examination.
The effect of 2% pilocarpine nitrate in countering mydriasis, cycloplegia, and change in visual acuity due to 0.5% tropicamide was studied in 23 healthy volunteers. There was no significant difference in the decrease in pupil size or the rate of return of accommodation between the eye that received pilocarpine and the control eye. The effect of tropicamide on visual acuity was slight. In four (17%) of 23 eyes that received pilocarpine, visual acuity was reduced to 6/36 or worse. It is suggested that the use of 2% pilocarpine in the attempted reversal of 0.5% tropicamide to improve a patient's vision is not helpful and may possibly be harmful.
The aim of the study was to determine the effect on driving of restricting vision. This was undertaken by comparing the driving performance of young, normal subjects under conditions of simulated visual impairment with a baseline condition. Visual impairment was simulated using goggles designed to replicate the effects of cataracts, binocular visual field restriction, and monocular vision. All subjects had binocular visual acuity greater than 6/12 when wearing the goggles and thus satisfied the visual requirements for a driver's license. Driving performance was assessed on a closed-road circuit for a series of driving tasks including peripheral awareness, maneuvering, reversing, reaction time, speed estimation, road position, and time to complete the course. Simulated cataract resulted in the greatest detriment to driving performance, followed by binocular visual field restriction. The monocular condition did not significantly affect driving performance for any of the driving tasks assessed.
A test of static (high-contrast) visual acuity is the most prevalent vision test used to screen driver license applicants worldwide, even though research has largely failed to provide convincing empirical evidence for its role in traffic accidents. The purpose of this research was to evaluate the effect of visual acuity degradation on different components of the driving task. Participants were 24 young licensed drivers (15 men, 9 women) with normal vision. Driving performance was measured while participants wore modified swimmer's goggles to which blurring lenses were affixed in amounts necessary to produce binocular visual acuity levels of 20/20, 20/40 (the prevalent acuity standard for driving), 20/100, and 20/200. Driving performance was measured using the closed-road method of Wood and Troutbeck (1994). Acuity degradation produced significant decrements in road sign recognition and road hazard avoidance as well as significant increments in total driving time. Participants' abilities to estimate whether clearances between pairs of traffic cones were sufficiently wide to permit safe passage of the vehicle and to slalom through a series of traffic cones were relatively unaffected by acuity degradation. Thus the latter tasks appear to be mediated by aspects of central and peripheral vision that are relatively unaffected by optical blur. Potential applications of this type of research include the development of procedures for defining empirically justifiable vision standards for driver licensure.
Eye is the official journal of the Royal College of Ophthalmologists. It aims to provide the practising ophthalmologist with information on the latest clinical and laboratory-based research.