Hazard Perception in Visually Impaired Drivers Who Use Bioptic Telescopes.

Purpose: Bioptic telescopic spectacles can allow individuals with central vision impairment to obtain or maintain driving privileges. The purpose of this study was to (1) compare hazard perception ability among bioptic drivers and traditionally licensed controls, (2) assess the impact of bioptic telescopic spectacles on hazard perception in drivers with vision impairment, and (3) analyze the relationships among vision and hazard detection in bioptic drivers. Methods: Visual acuity, contrast sensitivity, and visual field were measured for each participant. All drivers completed the Driving Habits Questionnaire. Hazard perception testing was conducted using commercially available first-person video driving clips. Subjects signaled when they could first identify a traffic hazard requiring a change of speed or direction. Bioptic drivers were tested with and without their bioptic telescopes in alternating blocks. Hazard detection times for each clip were converted to z-scores, converted back to seconds using the average response time across all videos, and then compared among conditions. Results: Twenty-one bioptic drivers and 21 normally sighted controls participated in the study. The hazard response time of bioptic drivers was improved when able to use the telescope (5.4 ± 1.4 seconds vs 6.3 ± 1.8 seconds without telescope); however, it remained significantly longer than for controls (4.0 ± 1.4 seconds). Poorer visual acuity, contrast sensitivity, and superior visual field sensitivity loss were related to longer hazard response times. Conclusions: Drivers with central vision loss had improved hazard response times with the use of bioptic telescopic spectacles, although their responses were still slower than normally sighted control drivers. Translational Relevance: The use of a bioptic telescope by licensed, visually impaired drivers improves their hazard detection speed on a video-based task, lending support to their use on the road.

Driving Difficulties and Preferences of Advanced Driver Assistance Systems by Older Drivers With Central Vision Loss.

Purpose: The purpose of this study was to investigate driving difficulties and Advanced Driver Assistance Systems (ADAS) use and preferences of drivers with and without central vision loss (CVL). Methods: Fifty-eight drivers with CVL (71 ± 13 years) and 68 without (72 ± 8 years) completed a telephone questionnaire. They rated their perceived driving difficulty and usefulness of technology support in 15 driving situations under good (daytime) and reduced visibility conditions, and reported their use experience and preferences for 12 available ADAS technologies. Results: Drivers with CVL reported more difficulty (P = 0.002) and greater usefulness of technology support (P = 0.003) than non-CVL drivers, especially in reduced visibility conditions. Increased driving difficulty was associated with higher perceived technology usefulness (r = 0.34, P < 0.001). Dealing with blind spot road users, glare, unexpected pedestrians, and unfamiliar areas were perceived as the most difficult tasks that would benefit from technology support. Drivers with CVL used more advanced ADAS features than non-CVL drivers (P = 0.02), preferred to own the blind spot warning, pedestrian warning, and forward collision avoidance systems, and favored ADAS support that provided both information and active intervention. The perceived benefits of and willingness to own ADAS technologies were high for both groups. Conclusions: Drivers with CVL used more advanced ADAS and perceived greater usefulness of driver assistance technology in supporting difficult driving situations, with a strong preference for collision prevention support. Translational Relevance: This study highlights the specific technology needs and preferences of older drivers with CVL, which can inform future ADAS development, evaluation, and training tailored to this group.

Quality of life after wearing multifocal contact lenses for myopia control for 2 weeks in the BLINK Study.

PURPOSE: To validate Pediatric Refractive Error Profile 2 (PREP2) subscales that can be used to evaluate contact lens wearers and compare vision-specific quality of life measurements between children wearing multifocal and single vision contact lenses for 2 weeks. METHODS: Two hundred and ninety-four myopic children aged 7-11 years (inclusive) were enrolled in the 3-year, double-masked Bifocal Lenses In Nearsighted Kids (BLINK) Study. Participants completed the PREP2 survey after having worn contact lenses for 2 weeks. The Vision, Symptoms, Activities and Overall PREP2 subscales were used to compare participants' subjective assessment while wearing +1.50 or +2.50 D add multifocal or single vision contact lenses. Rasch analysis was used to validate each subscale and to compare participants' subjective assessment of contact lens wear. RESULTS: Item fit to the Rasch model was good for all scales, with no individual items having infit mean square statistics outside the recommended range (0.7-1.3). Response category function was acceptable for all subscales, with ordered category thresholds. Measurement precision, assessed by the Rasch person reliability statistic, was less than ideal (≥0.8) for three of the subscales, but met the minimum acceptable standard of 0.5. Scores for the Vision subscale differed by treatment assignment (p = 0.03), indicating that participants with the highest add power reported statistically worse quality of vision, although the difference was only 3.9 units on a scale of 1-100. Girls reported fewer symptoms than boys (p = 0.006), but there were no other differences between boys and girls. CONCLUSIONS: Rasch analysis demonstrates that the PREP2 survey is a valid instrument for assessing refractive error-specific quality of life. These results suggest that vision-related quality of life is not meaningfully affected by 2 weeks of soft multifocal contact lens wear for myopia control.

Examining daily disposable soft contact lens wearers' attitudes and beliefs using the Health Belief Model.

PURPOSE: To use the Health Belief Model (HBM) to understand daily disposable (DD) soft contact lens (SCL) wearers' attitudes and beliefs. METHODS: A convenience sample of DD SCL wearers (18-33 years) was enrolled at two sites. Participants were queried about demographics, SCL wear and HBM constructs. Rasch analysis was used to assess the psychometric properties of the survey instrument and generate scores for each HBM subscale. ANOVA was used to determine relationships among HBM constructs, subject demographics and DD SCL-related health behaviours. RESULTS: One hundred people participated (mean ± SD), age = 24.2 ± 3.9 years, 76% female. Thirty-seven percent reported sleeping in DD SCLs and 25% reported reusing DD SCLs. Self-report of reusing DD SCLs was associated with scores on the benefits: reuse (p = 0.02) and barriers (p = 0.007) subscales, and sleeping in lenses was associated with scores on the susceptibility (p = 0.05), benefits: wear behaviours (p = 0.006) and barriers (p = 0.01) subscales. Rasch analysis showed some subscales demonstrated multidimensionality. CONCLUSIONS: Selected health belief constructs were associated with DD SCL-related behaviours including reusing and overnight wear. Increased understanding of SCL attitudes and beliefs could inform patient education and interventions to decrease risks associated with improper SCL wear.

Use and Perceptions of Advanced Driver Assistance Systems by Older Drivers With and Without Age-Related Macular Degeneration.

Purpose: Advanced driver assistance systems (ADAS) have been reported to improve the safety of elderly and normally sighted drivers. The purpose of this study was to assess exposure to, perceived safety of, comfort level with, and interest in using ADAS among drivers with age-related macular degeneration (AMD). Methods: Current drivers aged 60+ years were recruited at four US sites to complete a survey about ADAS and driving habits. Frequency of use and/or perceptions of eight ADAS were investigated. An avoidance score was generated using questions about difficult driving situations. Results: The survey was completed by 166 participants (80 with AMD vs. 86 without). Participants with AMD had worse self-rated vision than those without (34% vs. 2% poor or fair rating), and drove fewer weekly miles (median [interquartile range [IQR] 30 [15 to 75] vs. 60 [30 to 121] miles, P = 0.002). Participants with AMD reported more avoidance of difficult driving situations (P < 0.001). There was no difference in the number of ADAS used by AMD status (median [IQR for AMD = 2.5 [1 to 5] vs. 3 [2 to 4] without, P = 0.87). Greater reported number of ADAS used was associated with less avoidance of difficult situations (P = 0.02). The majority perceived improved safety with most ADAS. Conclusions: Many drivers with AMD utilize common ADAS, which subjectively improve their road safety and may help to reduce self-imposed restrictions for difficult situations and mileage. Translational Relevance: Drivers with AMD are adopting readily available ADAS, for which they reported potential benefits, such as safety and less restrictive driving.

Vision, Driving Exposure, and Collisions in Bioptic Drivers.

SIGNIFICANCE: Lack of knowledge regarding the mileage driven by drivers with low vision who use bioptic telescopes could obscure the relationship between vision and road safety. This study provides data suggesting that worse vision is correlated with less mileage driven but more collisions per mile in bioptic drivers. PURPOSE: The purpose of this study was to determine whether vision or demographic factors predict mileage driven in bioptic drivers and per-mile motor vehicle collision rate and also to compare the collision rate of bioptic drivers with previous estimates for the general population. METHODS: Driver data were collected retrospectively from clinic records. Collision data were collected from the Ohio Bureau of Motor Vehicles database. Subjects were also asked to estimate their yearly mileage. Regression models were used to investigate relationships between vision and collision rates. RESULTS: Seventy-three licensed Ohio bioptic drivers (36 male) were included. Mean ± standard deviation age was 51 ± 16 years. Mean logMAR visual acuity was 0.67 (approximately 20/100). Mean log contrast sensitivity was 1.57. Mean reported annual mileage was 9746. Age, sex, and previous (nonbioptic) driving experience were not associated with mileage. LogMAR visual acuity was inversely related to mileage (P = .02), and contrast sensitivity (P = .01) and horizontal visual field (P = .02) were directly associated with mileage. Visual acuity (P = .02) and visual field (P = .005), but not contrast sensitivity (P = .19), were associated with number of collisions. CONCLUSIONS: Visual acuity, visual field, and contrast sensitivity were associated with driving exposure in bioptic drivers (with drivers with poorer vision reporting lower annual mileage), and poorer visual acuity and visual field were associated with more collisions. The per-mile collision rate for bioptic drivers was within the range of that previously reported for fully sighted drivers, although higher than would be expected for fully sighted drivers of similar age distribution.

Bioptic Telescope Use in Naturalistic Driving by People with Visual Impairment.

Purpose: The purpose of this study was to investigate the telescope use behaviors in natural daily driving of people with reduced visual acuity licensed to drive with a bioptic (a small spectacle-mounted telescope). Methods: A large dataset (477 hours) of naturalistic driving was collected from 19 bioptic drivers (visual acuity 20/60 to 20/160 without the telescope). To reduce the data volume, a multiloss 50-layer deep residual neural network (ResNet-50) was used to detect potential bioptic telescope use events. Then, a total of 120 hours of selected video clips were reviewed and annotated in detail. Results: The frequency of looking through their telescopes ranged from 4 to 308 times per hour (median: 27, interquartile range [IQR], 19-75), with each bioptic use lasting median 1.4 seconds (IQR, 1.2-1.8). Thus, participants spent only 1.6% (IQR, 0.7%-3.5%) driving time with their telescopes aiding their vision. Bioptic telescopes were used most often for checking the road ahead (84.8%), followed by looking at traffic lights (5.3%), and reading road signs (4.6%). Conclusions: In daily driving, the bioptic drivers mostly (>98% of driving time) drove under low visual acuity conditions. The bioptic telescope was mainly used for observing road and traffic conditions in the distance for situational awareness. Only a small portion of usage was for road sign reading. Translational Relevance: This study provides new insights into how the vision rehabilitation device-bioptic telescopes are used in daily driving. The findings may be helpful for designing bioptic driving training programs.

Evaluation of the Driving Safety of Visually Impaired Bioptic Drivers Based on Critical Events in Naturalistic Driving.

Purpose: Visually impaired people may be allowed to drive if they wear bioptic telescopes. Bioptic driving safety is debatable, especially given that the telescopes are seldom used by most bioptic drivers. This preliminary study examined bioptic safety based on critical events that occurred in naturalistic daily driving. Methods: Daily driving activities were recorded using in-car video recorders in 20 bioptic drivers (median age 55, visual acuity, 20/60-160) and 19 control subjects (median age 74) for two to eight weeks. In a secondary analysis, these subjects were compared with 44 cognitively impaired drivers with normal vision (median age 75). Results: In 292 hours of driving by bioptic drivers and 169 hours by control drivers, seven bioptic drivers and three control drivers had eight and four near-collisions, respectively. Near-collision survival times were not significantly different between the two groups (hazard ratio [HR] = 1.93, P = 0.591) according to Cox hazards regression. Even without compensation for bioptic drivers' longer driving exposure, their odds ratio (OR) was not statistically significant (OR = 2.88, P = 0.18). When including cognitively impaired drivers with normal vision, cognition was a significant predictor of near collisions (HR = 3.86, P = 0.036), but vision loss was not (HR = 0.47, P = 0.317). Conclusions: This preliminary study failed to find any evidence suggesting that bioptic drivers were more prone to near-collision than healthy drivers. Vision might be a less-significant factor than cognition. Translational Relevance: Given that bioptic drivers use the telescope for less than 2% of the driving time, this study suggests that driving safety might not be substantially affected even when visual acuity is in the low vision range.

Psychometric Analysis of the SPEED Questionnaire and CLDEQ-8.

Purpose: This study reports on the ability of the Standard Patient Evaluation of Eye Dryness (SPEED) questionnaire to detect dry eye (DE) symptoms in contact lens (CL) and non-CL wearers. Methods: The SPEED questionnaire was administered to all subjects while the Contact Lens Dry Eye Questionnaire-8 (CLDEQ-8) was only administered to CL wearers. Tear meniscus heights (TMH) were measured, and the phenol red thread (PRT) test was conducted. These tests along with self-reported DE were used to identify subjects with dry eye disease (DED). Rasch analysis was performed to evaluate the questionnaires for measurement precision and unidimensionality, and the scores from these Rasch analyses were used to understand their ability to predict measures of DED. Results: We enrolled 284 subjects (150 CL and 134 non-CL wearers). Mean subject age was 39.4 ± 14.2 years. Rasch analysis yielded a multidimensional short form of the SPEED questionnaire (8-items) and a unidimensional short form of the CLDEQ-8 (4-item). Scores from both questionnaires were significantly associated with self-reported DE in CL and non-CL wearers. Scores of the 8-item SPEED questionnaire were associated with DED status in non-CL wearers but not in CL wearers while 4-item CLDEQ scores were associated with DED status in CL wearers. TMH or PRT were not associated with either questionnaire in CL or non-CL wearers. Conclusions: The 8-item SPEED questionnaire demonstrated adequate measurement precision with evidence of quantifying multiple symptoms categories while the 4-item CLDEQ-8 primarily quantified DE symptoms. Questionnaire scores were associated with self-reported DE, which suggests that they may have utility in both populations analyzed.

The Ohio Contrast Cards: Visual Performance in a Pediatric Low-vision Site.

SIGNIFICANCE: This report describes the first clinical use of the Ohio Contrast Cards, a new test that measures the maximum spatial contrast sensitivity of low-vision patients who cannot recognize and identify optotypes and for whom the spatial frequency of maximum contrast sensitivity is unknown. PURPOSE: To compare measurements of the Ohio Contrast Cards to measurements of three other vision tests and a vision-related quality-of-life questionnaire obtained on partially sighted students at Ohio State School for the Blind. METHODS: The Ohio Contrast Cards show printed square-wave gratings at very low spatial frequency (0.15 cycle/degree). The patient looks to the left/right side of the card containing the grating. Twenty-five students (13 to 20 years old) provided four measures of visual performance: two grating card tests (the Ohio Contrast Cards and the Teller Acuity Cards) and two letter charts (the Pelli-Robson contrast chart and the Bailey-Lovie acuity chart). Spatial contrast sensitivity functions were modeled using constraints from the grating data. The Impact of Vision Impairment on Children questionnaire measured vision-related quality of life. RESULTS: Ohio Contrast Card contrast sensitivity was always less than 0.19 log10 units below the maximum possible contrast sensitivity predicted by the model; average Pelli-Robson letter contrast sensitivity was near the model prediction, but 0.516 log10 units below the maximum. Letter acuity was 0.336 logMAR below the grating acuity results. The model estimated the best testing distance in meters for optimum Pelli-Robson contrast sensitivity from the Bailey-Lovie acuity as distance = 1.5 - logMAR for low-vision patients. Of the four vision tests, only Ohio Contrast Card contrast sensitivity was independently and statistically significantly correlated with students' quality of life. CONCLUSIONS: The Ohio Contrast Cards combine a grating stimulus, a looking indicator behavior, and contrast sensitivity measurement. They show promise for the clinical objective of advising the patient and his/her caregivers about the success the patient is likely to enjoy in tasks of everyday life.

Measurement of Perceived Stress in Age-Related Macular Degeneration.

PURPOSE: To validate the Perceived Stress Scale (PSS) in patients with age-related macular degeneration (AMD) using Rasch analysis. METHODS: Study participants with AMD were recruited from the retina service of the Department of Ophthalmology at the Ohio State University during clinical visits for treatment or observation. Visual acuity with habitual distance correction was assessed. A 10-item version of the PSS was administered in large print or by reading the items to the patient. Rasch analysis was used to investigate the measurement properties of the PSS, including fit to the model, ability to separate between people with different levels of perceived stress, category response structure performance, and unidimensionality. RESULTS: A total of 137 patients with a diagnosis of AMD were enrolled. The mean (±SD) age of participants was 82 ± 9 years. Fifty-four percent were female. Median Early Treatment of Diabetic Retinopathy Study (ETDRS) visual acuity of the better eye was 65 letters (Snellen 20/50), with a range of approximately 20/800 to 20/15. Forty-seven percent of participants were receiving an anti-VEGF injection on the day of the study visit. The response category structure was appropriate. One item, "How often have you felt confident in your ability to handle your personal problems?" was removed due to poor fit statistics. The remaining nine items showed good fit to the model, acceptable measurement precision as assessed by the Rasch person separation statistic, and unidimensionality. There was some evidence of differential item functioning by age and visual acuity. CONCLUSIONS: The Perceived Stress Scale demonstrated acceptable measurement properties and may be useful for the measurement of perceived stress in patients with AMD.

Previous Driving Experience, but Not Vision, Is Associated With Motor Vehicle Collision Rate in Bioptic Drivers.

PURPOSE: Bioptic telescopic spectacles (BTS) consist of a small telescope (or telescopes) mounted high in a pair of spectacle lenses. More than 40 states allow for some form of bioptic driving licensure for people with decreased central vision. The purpose of this study was to determine significant associations among previous driving experience, vision, and motor vehicle collisions (MVCs) for bioptic drivers in Ohio. METHODS: We conducted a retrospective study of patients who received a vision examination and subsequently obtained bioptic licensure. We obtained driving records from the Ohio Bureau of Motor Vehicles in order to determine MVC involvement. Relationships among vision measures, age, sex, previous experience, and MVCs were investigated using time-to-event analysis and the Cox proportional hazards regression model. RESULTS: We identified 237 bioptic drivers (65% male). Age at initial exam ranged from 16 to 81 years, and mean visual acuity was approximately 20/120. The number of MVCs per driver ranged from 0 to 11, with 124 (52%) drivers having had at least one MVC. Visual acuity and contrast sensitivity were not significant predictors of MVC. Drivers without previous driving experience were significantly more likely to have been involved in an MVC (P < 0.001), and this association remained significant after adjusting for age and sex (P = 0.01). The rate of MVC per year decreased steadily over a 10-year period for drivers without previous experience. CONCLUSIONS: Previous nonbioptic driving experience, but not visual acuity or contrast sensitivity, was associated with yearly MVC rate in bioptic drivers.

Vision, training hours, and road testing results in bioptic drivers.

PURPOSE: Bioptic telescopic spectacles can be used by people with central visual acuity that does not meet the state standards to obtain an unrestricted driver's license. The purpose of this study was to examine the relationships among visual and demographic factors, training hours, and the results of road testing for bioptic drivers. METHODS: A retrospective study of patients who received an initial daylight bioptic examination at the Ohio State University and subsequently received a bioptic license was conducted. Data were collected on vision including visual acuity, contrast sensitivity, and visual field. Hours of driver training and results of Highway Patrol road testing were extracted from records. Relationships among vision, training hours, and road testing were analyzed. RESULTS: Ninety-seven patients who completed a vision examination between 2004 and 2008 and received daylight licensure with bioptic telescopic spectacles were included. Results of the first Highway Patrol road test were available for 74 patients. The median (interquartile range) hours of training before road testing was 21 (17) hours (range, 9 to 75 hours). Candidates without previous licensure were younger (p < 0.001) and had more documented training (p < 0.001). Lack of previous licensure and more training were significantly associated with having failed a portion of the Highway Patrol test and points deducted on the road test. CONCLUSIONS: New bioptic drivers without previous nonbioptic driving experience required more training and performed more poorly on road testing for licensure than those who had previous nonbioptic licensure. No visual factor was predictive of road testing results after adjustment for previous experience. The hours of training received remained predictive of road testing outcome even with adjustment for previous experience. These results suggest that previous experience and trainer assessments should be investigated as potential predictors of road safety in bioptic drivers in future studies.

Rasch analysis of the Ocular Surface Disease Index (OSDI).

PURPOSE: The Ocular Surface Disease Index (OSDI) is a 12-item scale for the assessment of symptoms related to dry eye disease and their effect on vision. Its reliability and validity have been investigated within the classical test theory framework and, more recently, using Rasch analysis. The purpose of the present analysis was to more completely investigate the functioning of its response category structure, the validity of its three subscales, and the unidimensionality of the latent construct it is intended to assess. METHODS: Responses to the OSDI from 172 females participating in the Dry Eye in Postmenopause (DEiM) study who had previously been diagnosed with dry eye or reported significant ocular irritation and dryness were analyzed. Response category structure and item fit statistics were evaluated for assessment of model fit. Person separation statistics were used to examine the validity of the subscales. Unidimensionality was assessed by principal component analysis (PCA) of model residuals. RESULTS: The recommended five-category response structure resulted in disordered response thresholds. A four-category structure resulted in ordered thresholds. Item infit statistics were acceptable for all 12 items. Person separation with this category structure was adequate, with a person separation index of 2.16. None of the three subscales demonstrated adequate person separation. PCA showed one other significant factor onto which the three environmental items loaded significantly. CONCLUSIONS: All items demonstrated acceptable fit to the model after collapsing categories to order the response thresholds. The original subscales did not prove valid, and there is some evidence of multidimensionality and poor targeting.

Abandonment of low-vision devices in an outpatient population.

PURPOSE: To investigate abandonment rate of prescribed low-vision devices for near tasks and factors associated with abandonment in a U.S. outpatient population. METHODS: A telephone survey was administered to 88 patients with low vision from four clinical sites about 1 year after examination and prescription of devices. Patients were surveyed on timing and frequency of use and reasons for abandonment of devices. The main outcome measure (abandonment) was defined as patient report of no use of prescribed device in the previous 3 months. Multivariate logistic regression was used to investigate significant vision and demographic factors related to abandonment. RESULTS: Of 119 prescribed devices, 19% (95% CI, 12 to 26) had not been used within the previous 3 months. Mean (±SD) better eye visual acuity at examination was 0.61 ± 0.29 logMAR, and mean age was 77 ± 17 years. Mean time between device prescription and survey was 11 ± 3 months. Device abandonment was not associated with age (p = 0.863), time since prescription (p = 0.125), visual acuity (p = 0.804), or category of magnification device (spectacle, handheld, stand, or video) (p = 0.412). There was a significant association between documented non-central visual field loss and abandonment of magnification device (p = 0.046). Repeat administration of the survey resulted in the same abandonment classification in 15 of 15 patients (100%). CONCLUSIONS: Abandonment rate was similar for this outpatient population to those previously reported in the U.S. veteran inpatient population and in other countries. Patients with visual field loss may be more likely to abandon prescribed devices.

Comparison of scoring approaches for the NEI VFQ-25 in low vision.

PURPOSE: The aim of this study was to evaluate different approaches to scoring the National Eye Institute Visual Functioning Questionnaire-25 (NEI VFQ-25) in patients with low vision including scoring by the standard method, by Rasch analysis, and by use of an algorithm created by Massof to approximate Rasch person measure. Subscale validity and use of a 7-item short form instrument proposed by Ryan et al. were also investigated. METHODS: NEI VFQ-25 data from 50 patients with low vision were analyzed using the standard method of summing Likert-type scores and calculating an overall average, Rasch analysis using Winsteps software, and the Massof algorithm in Excel. Correlations between scores were calculated. Rasch person separation reliability and other indicators were calculated to determine the validity of the subscales and of the 7-item instrument. RESULTS: Scores calculated using all three methods were highly correlated, but evidence of floor and ceiling effects was found with the standard scoring method. None of the subscales investigated proved valid. The 7-item instrument showed acceptable person separation reliability and good targeting and item performance. CONCLUSIONS: Although standard scores and Rasch scores are highly correlated, Rasch analysis has the advantages of eliminating floor and ceiling effects and producing interval-scaled data. The Massof algorithm for approximation of the Rasch person measure performed well in this group of low-vision patients. The validity of the subscales VFQ-25 should be reconsidered.

Development of a battery of functional tests for low vision.

PURPOSE: We describe the development and evaluation of a battery of tests of functional visual performance of everyday tasks intended to be suitable for assessment of low vision patients. METHODS: The functional test battery comprises-Reading rate: reading aloud 20 unrelated words for each of four print sizes (8, 4, 2, & 1 M); Telephone book: finding a name and reading the telephone number; Medicine bottle label: reading the name and dosing; Utility bill: reading the due date and amount due; Cooking instructions: reading cooking time on a food package; Coin sorting: making a specified amount from coins placed on a table; Playing card recognition: identifying denomination and suit; and Face recognition: identifying expressions of printed, life-size faces at 1 and 3 m. All tests were timed except face and playing card recognition. Fourteen normally sighted and 24 low vision subjects were assessed with the functional test battery. Visual acuity, contrast sensitivity, and quality of life (National Eye Institute Visual Function Questionnaire 25 [NEI-VFQ 25]) were measured and the functional tests repeated. Subsequently, 23 low vision patients participated in a pilot randomized clinical trial with half receiving low vision rehabilitation and half a delayed intervention. The functional tests were administered at enrollment and 3 months later. RESULTS: Normally sighted subjects could perform all tasks but the proportion of trials performed correctly by the low vision subjects ranged from 35% for face recognition at 3 m, to 95% for the playing card identification. On average, low vision subjects performed three times slower than the normally sighted subjects. Timed tasks with a visual search component showed poorer repeatability. In the pilot clinical trial, low vision rehabilitation produced the greatest improvement for the medicine bottle and cooking instruction tasks. CONCLUSIONS: Performance of patients on these functional tests has been assessed. Some appear responsive to low vision rehabilitation.

An evaluation of the Mars Letter Contrast Sensitivity Test.

PURPOSE: The Mars Letter Contrast Sensitivity Test (initially known as the Lighthouse Letter Contrast Sensitivity Test) is similar in design to the Pelli-Robson Test but may offer several advantages. This study evaluates the repeatability of the Mars test and its agreement with the Pelli-Robson test in normal and low-vision subjects. METHODS: Fifty-four subjects were tested (age 22-86 years), including 20 normally sighted young adults, 17 normally sighted older adults, and 17 adults with low vision (20/16 to 20/250). Subjects were tested with both contrast sensitivity tests and with the ETDRS visual acuity chart. After a short break, subjects were retested with an alternate form of each contrast sensitivity test. The chart forms used (two Pelli-Robson and three Mars) and the order of testing were varied systematically. Testing was monocular with habitual correction and, for subjects over 40 years of age, included appropriate near add. Letter-by-letter scoring was used for both tests. Repeatability and agreement were assessed by determining the 95% limits of agreement (LoA): +/- 1.96 standard deviations of the differences between administrations or tests. RESULTS: The Mars test showed excellent agreement with the Pelli-Robson test, with 95% LoA of +/- 0.21 log units for all subjects. The Mars test was similarly repeatable (95% LoA = +/-0.20 log units) to the Pelli-Robson test (95% LoA = +/-0.20 log units) among all subjects. CONCLUSION: The new Mars Letter Contrast Sensitivity Test shows excellent agreement with the Pelli-Robson test and has similar repeatability. There are subtle differences in the actual contrast levels on different forms of the Mars test, and adjusting for these differences leads to superior repeatability of the Mars test. Thus, the Mars test may be a useful alternative to the Pelli-Robson test offering several advantages, including smaller size, improved durability, and ease of use.