Snellen iPad App versus Traditional Light-Box Snellen Chart in Distance Visual Acuity.

This study aimed to discover distance visual acuity (VA) assessments through the display of the Snellen chart on the iPad tablet. The findings are equivalent to those obtained using the conventional light-box Snellen chart. In this work, the Snellen iPad app and Eye Chart HD iOS app are utilized among the participants in the Ophthalmology Outpatient Department (OPD) for determining VA. A cross-sectional method was used for the examination, which included 100 new patients who were chosen by random selection. The age requirement for new patients was 8 years and up for both genders. Patients with a VA of less than 6/30 were disqualified from the experiment. Two testing modalities are used to measure VA, such as the iPad Mini 2 with the iOS software Eye Chart HD and the classic Snellen light-box chart. The observation revealed that the Snellen iPad app and the classic light-box Snellen chart produced equivalent findings. The classic Snellen chart may have been memorized by participants before their eye examination, undermining the accuracy of the conclusions of the initial testing modality used. Patient-related variables were also identified as confounders. Future studies should adjust the brightness of the iPad Mini 2 and the traditional light-box Snellen chart to make sure that neither experiment modality's brightness affects the accuracy of the findings. Future research should also investigate the use of premium apps, use both devices, and employ a bigger sample size.

Measuring the impact of suppression on visual acuity in children with amblyopia using a dichoptic visual acuity chart.

Purpose: To develop a novel dichoptic visual acuity chart that measures the impact of interocular suppression on the visual acuity of each eye when two eyes are open. Methods: Fifty-four subjects (19 anisometropic amblyopia, 20 treated amblyopia, and 15 normal children) participated in this study. The visual acuity that was tested under dichoptic-optotypes condition (i.e., presented optotypes to the untested eye) was compared with that under monocular condition (i.e., cover the untested eye with opaque patch). Visual acuity differences between these two conditions were compared among the three groups. The correlations between visual acuity differences and the depth of interocular suppression were then computed. Some participants performed the visual acuity test under dichoptic-luminance condition (i.e., presented mean luminance to the untested eye), and the test-retest reliability was established. Results: A reduced visual acuity of the non-dominant eye was found in the dichoptic-optotypes condition for the amblyopia group (P < 0.001) and the treated group (P = 0.001); the difference in the treated group was less than that in the amblyopia group (P < 0.001) but more than that in the normal group (P = 0.026). A significant correlation was found between the visual acuity differences and the depth of suppression, which was tested with a binocular phase combination task (P = 0.005). No change was found in the dichoptic-luminance condition. Conclusion: The amblyopic eye and the previous amblyopic eye seem to suffer from a reduced visual acuity when two eyes are open due to suppression. This was successfully captured by our novel and reliable dichoptic-optotypes visual acuity chart.

Measurement of visual acuity with a digital eye chart: optotypes, presentation modalities and repeatability

Purpose: Digital or computerised eye charts are becoming standard in the examination of visual acuity. Each instrument allows the selection of different optotypes, presentation modalities, and crowding. The aim of this study was to examine the differences in visual acuity (VA) measurement using a digital eye chart, comparing different optotypes and procedures, together with an evaluation of the repeatability of the measurement.MethodsTwo groups of 52 participants aged between 18 and 31 years participated in the study. In the first experiment, VA thresholds were measured using LEA Symbols, Tumbling E, and Landolt Rings in monocular and binocular conditions using single line presentation and QUEST presentation. In the second experiment, we have compared all modalities of presentation together with a paper eye-chart and test the repeatability.ResultsThe results showed that thresholds for LEA Symbols are low. The modality of presentation affects these thresholds. For Landolt Rings and Tumbling E, the QUEST procedure gave significantly better thresholds than line presentation, while this difference was absent for LEA Symbols. In comparing all modalities of presentation, single letter and line presentation showed similar values, slightly better than block presentation. Paper eye-charts showed better values of VA. Repeatability and agreement were good for all presentations, but best for QUEST.ConclusionsThe QUEST modality of presentation provides a better threshold than line presentation except for LEA Symbols. Examiners using digital eye charts must take into account that not all modalities of presentation and optotypes are equivalent and give different VA thresholds. Specific thresholds need to be used for each optotype and presentation modality. (AU)

Comparison of Visual Acuity Measurement Using Three Methods: Standard ETDRS Chart, Near Chart and a Smartphone-Based Eye Chart Application.

PURPOSE: To validate the Rosenbaum near vision card (Near Chart) and a smartphone-based visual acuity (VA) test (Eye Chart) against a standard retro-illuminated Early Treatment Diabetic Retinopathy Study (ETDRS) chart within participants. MATERIALS AND METHODS: A cross-sectional study of participants aged ≥18 years was conducted. VA was measured in all participants using the ETDRS chart, Near Chart and smartphone-based Eye Chart application, respectively. VA was converted to logarithm of the minimum angle of resolution (logMAR) for statistical analysis. Eyes with ETDRS VA worse than 1.0 logMAR (20/200) were excluded. The main outcome measures were levels of agreement between VA measured using the Near Chart or Eye Chart application vs the ETDRS chart. RESULTS: A total of 295 eyes of 151 participants were included. One hundred participants (66.2%) were female and the mean age was 64.3 ± 12.5 years. Educational level was high school or below for 49% of participants and at Bachelor's degree or above for 51%. The median logMAR VAs of all eyes tested using the ETDRS chart, Near Chart and Eye Chart application were 0.1, 0.0 and 0.1, respectively. The median VA difference between the Near Chart vs ETDRS chart and Eye Chart application vs ETDRS chart was 0.0 logMAR in both cases for both the right eye (OD) and left eye (OS). Intraclass correlation coefficient (ICC) demonstrated a strong positive correlation between VA tested with the Near Chart vs ETDRS chart (OD: ICC=0.85; p<0.001, OS: ICC=0.77; p<0.001) and Eye Chart application vs ETDRS chart (OD: ICC=0.88; p<0.001, OS: ICC=0.74; p<0.001). CONCLUSION: VA measurements with the Near Chart and smartphone-based Eye Chart application corresponded well to the standard ETDRS chart, suggesting potential utility of alternative portable VA tests for in-office or remote vision monitoring, particularly during periods of physical distancing such as the Coronavirus disease 2019 (COVID-19) era.

Measurement of visual acuity with a digital eye chart: optotypes, presentation modalities and repeatability.

PURPOSE: Digital or computerised eye charts are becoming standard in the examination of visual acuity. Each instrument allows the selection of different optotypes, presentation modalities, and crowding. The aim of this study was to examine the differences in visual acuity (VA) measurement using a digital eye chart, comparing different optotypes and procedures, together with an evaluation of the repeatability of the measurement. METHODS: Two groups of 52 participants aged between 18 and 31 years participated in the study. In the first experiment, VA thresholds were measured using LEA Symbols, Tumbling E, and Landolt Rings in monocular and binocular conditions using single line presentation and QUEST presentation. In the second experiment, we have compared all modalities of presentation together with a paper eye-chart and test the repeatability. RESULTS: The results showed that thresholds for LEA Symbols are low. The modality of presentation affects these thresholds. For Landolt Rings and Tumbling E, the QUEST procedure gave significantly better thresholds than line presentation, while this difference was absent for LEA Symbols. In comparing all modalities of presentation, single letter and line presentation showed similar values, slightly better than block presentation. Paper eye-charts showed better values of VA. Repeatability and agreement were good for all presentations, but best for QUEST. CONCLUSIONS: The QUEST modality of presentation provides a better threshold than line presentation except for LEA Symbols. Examiners using digital eye charts must take into account that not all modalities of presentation and optotypes are equivalent and give different VA thresholds. Specific thresholds need to be used for each optotype and presentation modality.

Application of Correlation-Based Scoring Scheme for Visual Acuity Measurements in the Clinical Practice.

PURPOSE: Visual acuity tests are generally performed by showing eye charts to the subjects and registering their correct/incorrect identifications for the presented optotypes. We recently developed a correlation-based scoring method that significantly reduces the statistical error associated with relative letter legibility. In this paper, our purpose was to demonstrate the advantages and clinical utility of our scoring scheme compared to standard methods. METHODS: We developed a new computer-controlled measurement setup aligned with the ophthalmological standard. With this system, we presented the application of our correlation-based scoring in conventional clinical environment for 25 subjects and estimated the systematic error of the obtained acuity values. A separate experiment was performed by 14 additional subjects to reveal the test-retest variability of the new scoring method. RESULTS: The average systematic error relative to standard probability-based scoring is 0.01 logMAR over the examined subject group. Application of the correlation-based scheme when used in clinical environment with five letters per size decreases the repeatability error by ∼20% and increases diagnosis time by ∼10%. CONCLUSIONS: The new scoring scheme is directly applicable in clinical practice providing unbiased results with improved repeatability compared to standard visual acuity measurements. It reduces test-retest variability by the same amount as if the number of letters was doubled in traditional tests. TRANSLATIONAL RELEVANCE: Our new method is a promising alternative to conventional acuity tests in cases when high-precision measurements are required, for example evaluating implanted intraocular lenses, testing subjects with retinal diseases or cataract, and refractive surgery candidates.

Different trajectories in the development of visual acuity with different levels of crowding: The Milan Eye Chart (MEC).

Eye charts are typically optimized to assess visual acuity (VA) with constant and controlled spacing, while close-to-acuity crowding limits letter identification in the normal fovea when adjacent letters are closely spaced. Here we developed a clinical tool that enables the assessment of acuity with different levels of crowding. In a cross-sectional study, we examined the developmental trajectories with our newly devised Milan Eye Chart (MEC). A total of 252 children of 1st, 3rd and 5th grade were assessed with the MEC using SLOAN letter optotypes with 100%, 50%, 25% and 12.5% inter-optotype spacing. Results show an interaction between spacing and grade. The performance to the 100% standard VA was not significantly different among grades, while the narrow spaced acuity (12.5% spacing) strongly improved with the grade. The different trajectories of acuity measured with high spaced and low spaced eye-charts suggest that the mechanisms able to reduce the crowding effects develops later than VA, and it is, at least in part, dissociated by the psychophysiological development of lower level visual mechanisms. The MEC charts are feasible and useful in assessing visual acuity with different level of crowding during the whole lifespan. The opportunity to assess crowding-limited acuity in early age is particularly relevant since it plays a significant role in amblyopia screening.

Clinical Application of Microcomputer Optometer / 医疗卫生装备

Objective To discuss the principle and clinical application of microcomputer optometer.Methods The optometer is composed of singlechip,handle and LCD.The eyesight is examined by selecting exposure of random sample eye-chart mark 'E' within direction keys on the handle.Results The optometer has the merits of simple manipulation,exact result,small cubage,AC/DC power supply and so on.Besides,it prevents the testee from remembering eye-chart.Conclusion The optometer can be extensively used in hospital,school,every work unit or even family.

Development of Optometer Controlled by Micro-computer / 医疗卫生装备

Objective To develop a new optometer controlled by micro-computer.Methods With AT89C51 single-chip as hardware and programmed by C language,the instrument applied,the optometer adopted LCD and international standard optotype.The optotype had 14 lines of object-finders,and only one line of random characters was displayed on the screen every time.The optometry distance was 3m.All procedures were controlled by singlechip.Results The case of memorizing eye-chart was avoided and the optometry was every simple.Conclusion The instrument eliminates mirror used for optometry short distance,and the optometry results can be stored and printed.It also has the merits of small volume,precise manufacture,simple operation,low cost and AC/DC power supply.