Comparison of Foraging Interactive D-prime and Angular Indication Measurement Stereo with different methods to assess stereopsis.

PURPOSE: Stereopsis is a critical visual function, however clinical stereotests are time-consuming, coarse in resolution, suffer memorization artifacts, poor repeatability, and low agreement with other tests. Foraging Interactive D-prime (FInD) Stereo and Angular Indication Measurement (AIM) Stereo were designed to address these problems. Here, their performance was compared with 2-Alternative-Forced-Choice (2-AFC) paradigms (FInD Stereo only) and clinical tests (Titmus and Randot) in 40 normally-sighted and 5 binocularly impaired participants (FInD Stereo only). METHODS: During FInD tasks, participants indicated which cells in three 4*4 charts of bandpass-filtered targets (1,2,4,8c/° conditions) contained depth, compared with 2-AFC and clinical tests. During the AIM task, participants reported the orientation of depth-defined bars in three 4*4 charts. Stereoscopic disparity was adaptively changed after each chart. Inter-test agreement, repeatability and duration were compared. RESULTS: Test duration was significantly longer for 2-AFC (mean = 317s;79s per condition) than FInD (216s,18s per chart), AIM (179s, 60s per chart), Titmus (66s) or RanDot (97s). Estimates of stereoacuity differed across tests and were higher by a factor of 1.1 for AIM and 1.3 for FInD. No effect of stimulus spatial frequency was found. Agreement among tests was generally low (R2 = 0.001 to 0.24) and was highest between FInD and 2-AFC (R2 = 0.24;p<0.01). Stereoacuity deficits were detected by all tests in binocularly impaired participants. CONCLUSIONS: Agreement among all tests was low. FInD and AIM inter-test agreement was comparable with other methods. FInD Stereo detected stereo deficits and may only require one condition to identify these deficits. AIM and FInD are response-adaptive, self-administrable methods that can estimate stereoacuity reliably within one minute.

Development and Validation of Performance-Based Assessment of Daily Living Tasks in Age-Related Macular Degeneration.

Purpose: To establish the reliability and validity of five performance-based activities of daily living task tests (ADLTT), to correlate structure to function, to evaluate the impact of visual impairment (VI) on age-related macular degeneration (AMD), and to develop new outcome measures. Methods: A multidisciplinary team developed five ADLTTs: (1) reading test (RT); (2) facial expression (FE) recognition; (3) item search (IS) task; (4) money counting (MC) task; and (5) making a drink (MD), tested with binocular and monocular vision. ADLTTs were tested for known-group (i.e., difference between AMD group and controls) and convergent (i.e., correlation to other measures of visual function), validity metrics, and test-retest reliability in 36 patients with VI (visual acuity (logMAR VA > 0.4) in at least one eye caused by AMD versus 36 healthy controls without VI. Results: Compared to controls, AMD patients had a slower reading speed (-77.41 words/min; P < 0.001); took longer to complete MC using monocular worse eye and binocular vision (15.13 seconds and 4.06 seconds longer compared to controls, respectively; P < 0.001); and MD using monocular worse eye vision (9.37 sec; P = 0.033), demonstrating known-group validity. Only RT and MC demonstrated convergent validity, showing correlations with VA, contrast sensitivity, and microperimetry testing. Moderate to good test-retest reliability was observed for MC and MD (interclass correlation coefficient = 0.55 and 0.77; P < 0.001) using monocular worse eye vision. Conclusions: Real-world ADL functioning associated with VI-related AMD can be assessed with our validated ADLTTs, particularly MC and MD. Translational Relevance: This study validates visual function outcome measures that are developed for use in future clinical practice and clinical trials.

Combination of 2 test methods, single-picture optotype visual acuity chart and spot™ vision screener, in the eye health screening program for 3-year-old children in Tokyo: A retrospective, observational study.

To evaluate the usefulness of the Tokyo Metropolitan Government's Eye Health Screening Program for 3-year-old children, which combines the Single-Picture Optotype Visual Acuity Chart (SPVAC) and Spot™ Vision Screener (SVS) tests. This was a retrospective, observational, matched study. Patients who underwent the eye health screening program and had abnormalities were classified into 3 groups according to the outcomes of the SPVAC (SPVAC-passed, SPVAC-P; SPVAC-failed, SPVAC-F) and SVS (SVS-passed, SVS-P; SVS-failed, SVS-F) tests as follows: SPVAC-P/SVS-F, SPVAC-F/SVS-P, and SPVAC-F/SVS-F. We evaluated the age at examination, SPVAC and SVS test success rates, and SVS refractive power. Additionally, the rates of refractive error, amblyopia, and strabismus were compared among the 3 groups. The SPVAC-P/SVS-F, SPVAC-F/SVS-P, and SPVAC-F/SVS-F groups comprised 158, 28, and 74 eyes, respectively. The mean age was 37.4 months. The success rates of the SPVAC and SVS tests were 69.8% and 96.2%, respectively. The mean SVS hyperopia value in the SPVAC-F/SVS-F group (2.71 ±â€…1.50 D) was significantly higher than that of the SPVAC-P/SVS-F group. The mean SVS astigmatism and myopia values were -2.21 diopter (D) ±â€…1.09 D and -3.40 ±â€…1.82 D, respectively; they did not differ significantly from that of the SPVAC-P/SVS-F group. Significant differences were observed in the refractive error, amblyopia, and strabismus rates among the 3 groups. Regarding disease determination, no significant difference was observed among participants who passed and failed the SPVAC test, regardless of the outcome of the other test. However, a significant difference was observed between those passing and failing the SVS tests. The SPVAC method used to screen 3-year-old children should be modified to commence at 42 months of age or be replaced with a single Landolt C test. The SVS test is useful for screening younger patients. Furthermore, the SVS test showed that the degree of hyperopia was higher in patients who did not pass the SPVAC test.

Evaluation of 3D tablet-based stereoacuity test ASTEROID in children with normal and abnormal visual acuity.

PURPOSE: To assess the utility of 3D, tablet-based, glasses-free Accurate STEReotest (ASTEROID) in children compared with the Titmus test. METHODS: Children aged 5-13 years were enrolled in a single-center, nonrandomized, observational comparison study and analyzed by age (5-7 vs 8-13 years) and visual acuity (20/25 or better in both eyes vs abnormal). Each participant underwent both the ASTEROID and Titmus stereoacuity tests. Stereoacuity was defined as fine (≤60 arcsec), moderate (61-200 arcsec), coarse (201-1199 arcsec), or very coarse to nil (≥1200 arcsec). Agreement between the tests was assessed using a weighted kappa (κ) statistic based on all four categories. RESULTS: A total of 112 children were included: 28 aged 5-7 with normal visual acuity, 30 aged 5-7 with abnormal visual acuity, 34 aged 8-13 with normal visual acuity, and 20 aged 8-13 with abnormal visual acuity. Mean ASTEROID score was 688 ± 533 arcsec (range, 13-1200 arcsec). Agreement between ASTEROID and Titmus test scores for participants overall was moderate (κ = 0.52). By subgroup, agreement was fair for children 5-7 with abnormal visual acuity (κ = 0.31), moderate for children 5-7 with normal visual acuity (κ = 0.47) and children 8-13 with normal visual acuity (κ = 0.42), and substantial for children 8-13 with abnormal visual acuity (κ = 0.76). Where ASTEROID and Titmus score group varied, ASTEROID score was poorer in 94% (47/50) of cases. CONCLUSIONS: ASTEROID is a digital, tablet-based test that evaluates global stereopsis, does not require glasses, and provides a continuum of scores. Among children, ASTEROID has good agreement with the Titmus test; however, it may be more sensitive at detecting stereovision deficits. Further study is necessary to determine which test is more accurate.

Measuring Vision at Home in 2023.

Introduction: The ability to measure a patient's visual acuity at home (HVA) is by far the most desired remote telemedicine capability sought by ophthalmologists. Methods: A systematic literature review was done using Pubmed to search for publications from 2010 to 2022 in English reporting on 10 studies that compared a patient's HVA to the clinic visual acuity (CVA). Results: Approaches to measuring HVA included using a phone-based application, a physical chart, a computer, and a website. The most accurate of these was the use of personal computers (COMPlog, Macustat, Web based test) at home with a bias of 1 letter. The most accessible and reliable was the use of a printable visual acuity chart, available in the public domain, which had adifference between HVA and CVA of 1 to 3.5 letters. Phone apps (Verana Vision) and stand-alone websites (Farsight.com) both had a greater mean difference of about 6 letters, respectively,with a moderate correlation coefficient. Discussion: Overall, all three methodologies demonstrated a good negative predictive value demonstrating their potential use as an effective screening tool to flag drastic vision decline between clinic visits.

Toward an internationally accepted standard for reading charts.

Patients who suffer from sight-threatening eye diseases share a desire to regain a comfortable reading ability. In light of the modern advances achieved in ophthalmic diagnosis and therapy, and because a significant lack of comparability between reading charts still exists, there is an increasing need for a worldwide standard in the form of a norm for diagnostic reading charts. Already, applied advancements such as digital print, which allow a calibration of the print sizes of reading charts in correctly progressing geometric proportions by using the actual height of a lower case "x" in millimeters (x-height), and psychophysically standardizing reading charts and their test items by applying modern statistical methods have significantly contributed to establishing a norm for reading charts. In 2020, a proposal of the British delegation was accepted by the International Organization for Standardization (ISO) group "Visual Optics and Optical Instruments," and a working group was established. Bearing in mind the efforts of the ISO with regard to an international norm, this review article is intended to (a) give an overview of the historical background and related normative approaches for diagnostic reading tests used in ophthalmology and optometry, (b) explain psychophysical and technical concerns, and (c) discuss the possibilities and limits of concepts that seem relevant to developing a modern standard for reading charts.

Converting LEA to Pelli-Robson contrast sensitivity score in neuro-ophthalmology patients.

PURPOSE: The Pelli-Robson and LEA contrast sensitivity charts are commonly used in clinical settings to measure contrast sensitivity. Although the Pelli-Robson chart is considered the gold standard, it is limited by its bulky size. The LEA chart, on the contrary, offers a more practical and portable option that is still reliable. This has led to questions about whether we can predict Pelli-Robson scores based on LEA scores. This study developed a conversion method to help transition from the LEA chart to the Pelli-Robson chart and validate the conversion score. METHODS: In this retrospective study, we analyzed the relationship between LEA and the Pelli-Robson contrast sensitivity test. Our study examined a total of 120 eyes. We developed a conversion table through the equipercentile equating method. Subsequently, we assessed the reliability and accuracy of this algorithm for converting LEA results into Pelli-Robson contrast sensitivity scores. RESULTS: The study used a conversion table to convert LEA scores to Pelli-Robson scores. The conversion table achieved a reliability of 0.91 based on intraclass correlation, and the algorithm had an accuracy of 81.6% within a 1-point difference from the raw score. CONCLUSIONS: This study reported a reliable and comparable conversion algorithm for transforming LEA scores into converted estimated Pelli-Robson scores, thereby improving the usefulness of existing data in both clinical and research contexts.

Scotopic and Photopic Conventional Visual Acuity and Hyperacuity - Binocular Summation.

Purpose: The purpose of this study was to determine and compare binocular summation (BiS) of conventional visual acuity (cVA) versus hyperacuity (hVA) for photopic and scotopic luminance conditions as a potential biomarker to assess the outcome of interventions on binocular function. Methods: Sixteen young adults (age range [years] = 21-31; 8 women; cVA logMAR < 0.0) participated in this study. The Freiburg Visual Acuity Test (FrACT) was used for VA testing and retested on another day. Both cVA and hVA were determined for dark grey optotypes on light grey background. Participants underwent 40 minutes of dark adaptation prior to scotopic VA testing. Binocular and monocular VA testing was performed. The eye with better VA over the 2 days of testing was selected, the BiS was quantified (binocular VA - better monocular VA) and repeated measures ANOVAs were performed. Results: Binocular VA exceeded monocular VA for all luminance conditions, VA-types, and sessions. We report BiS estimates for photopic and scotopic cVA and hVA, (logMAR BiS ± SEM [decimal BiS]): photopic = -0.01 ± 0.01 [1.03] and -0.06 ± 0.03 [1.15]; and scotopic = -0.05 ± 0.01 [1.12] and -0.11 ± 0.04 [1.28], respectively). Improvement for binocular vision estimates ranged from 0.01 to 0.11 logMAR. A repeated-measures ANOVA (RM ANOVA) did not reveal significant effects of LUMINANCE or VA TYPE on BiS, albeit a trend for strongest BiS for scotopic hVA (15% vs. 28%, photopic versus scotopic, respectively) and weakest for photopic cVA (3% vs. 12%, photopic versus scotopic conditions, respectively). Conclusions: Our results indicate that BiS of VA is relevant to scotopic and photopic hVA and cVA. It appears therefore a plausible candidate biomarker to assess the outcome of retinal therapies restoring rod or cone function on binocular vision. Translational Relevance: Binocular summation of visual acuity might serve as a clinical biomarker to monitor therapy outcome on binocular rod and cone-mediated vision.

Evaluating distance stereoacuity in children 4-17 years of age with a novel digital application.

Distance stereoacuity measurement enables the evaluation and management of binocular vision disorders. Here, we compare the results obtained using standard tests for distance stereoacuity measurement with the novel STab test. We tested 87 children (4-17 years of age) using different tests for the quantification of stereopsis at distance: Distance Randot Stereotest (DRS), M&S random dots (M&S), and STab. A strong correlation was demonstrated between M&S-DRS (0.8), M&S-STab (0.81), DRS-STab (0.85) (all P < 0.0001). The limit of agreement between M&S and DRS was 0.45; between M&S and STab, 0.47; and between DRS and STab, 0.38. Our results suggest that all three methods can be used interchangeably.

Evaluation of contrast sensitivity in visually impaired individuals using K-CS test. A novel smartphone-based contrast sensitivity test-Design and validation.

BACKGROUND: To describe the development and investigate the accuracy of a novel smartphone-based Contrast Sensitivity (CS) application, the K-CS test. METHODS: A total of 67 visually impaired and 50 normal participants were examined monocularly using the novel digital K-CS test and the Pelli-Robson (PR) chart. The K-CS test examines letter contrast sensitivity in logarithmic units, using eight levels of contrast from logCS = ~0,1 to logCS = ~2,1 at two spatial frequencies of 1.5 and 3 cycles per degree (cpd). The K-CS test was compared to the gold standard, PR test and intra-session test repeatability was also examined. RESULTS: The K-CS test in normally sighted was found to agree well with the PR, providing comparable mean scores in logCS (±SD) (K-CS = 1.908 ± 0.06 versus PR = 1.93 ± 0.05) at 1.5 cpd and mean (± SD) logCS at 3 cpd (K-CS = 1.83 ± 0.13 versus PR = 1.86 ± 0.07). The mean best corrected visual acuity of visually impaired participants was 0.67 LogMAR (SD = 0.21) and the K-CS was also found to agree well with the Pelli-Robson in this group, with an equivalent mean (±SD) logCS at 1.5 cpd: (K-CS = 1.19 ± 0.27, PR = 1.15 ± 0.31), 3 cpd: K-CS = 1.01 ± 0.33, PR = 0.94 ± 0.34. Regarding the intra-session test repeatability, both the K-CS test and the PR test showed good repeatability in terms of the 95% limits of agreement (LoA): K-CS = ±0.112 at 1.5 cpd and ±0.133 at 3 cpd, PR = ±0.143 at 1.5 cpd and ±0.183 in 3 cpd in visually impaired individuals. CONCLUSION: The K-CS test provides a quick assessment of the CS both in normally sighted and visually impaired individuals. The K-CS could serve as an alternative tool to assess contrast sensitivity function using a smartphone and provides results that agree well with the commonly used PR test.

Effects of brightness variations on a smartphone-based version of Radner reading charts.

OBJECTIVE: The purpose of this study was to evaluate the equivalence of smartphone-based measurements of near visual acuity under different screen brightness conditions with a standard near visual acuity test. METHODS: On a sample of 85 participants, we have evaluated near visual acuity with a smartphone-based version of the Radner reading chart at three distinct screen brightness levels. Results have been compared with those obtained with classical Radner paper charts. RESULTS: We have found that, when a sufficient screen brightness is employed, the smartphone-based version of the Radner reading chart produces results that are in line with the paper Radner charts while low brightness levels lead to a significant underestimation of reading acuities. This result was consistent across different refractive conditions. CONCLUSIONS: In conclusion, we have shown that handheld devices, such as smartphones, can be potentially exploited for remote measurements of near visual acuity provided a correct control of brightness screen is employed.

Clinical report: Virtual reality enables comparable contrast sensitivity measurements to in-office testing (pilot study).

SIGNIFICANCE: Vision health disparities largely stem from inaccessibility to vision specialists. To improve patient access to vision tests and to expedite clinical workflows, it is important to assess the viability of virtual reality (VR) as a modality for evaluating contrast sensitivity. PURPOSE: This study aimed to assess the validity of a VR version of the Pelli-Robson contrast sensitivity test by comparing its results with those of the corresponding in-office test. METHODS: Twenty-eight participants (mean ± standard deviation age, 37.3 ± 20.5 years) with corrected vision were recruited for testing on a voluntary basis with randomized administration of the in-office test followed by the VR analog or vice versa. Nineteen participants took each test twice to assess test-retest consistency in each modality. Virtual reality tests were conducted on a commercial Pico Neo Eye 2 VR headset, which has a 4K screen resolution. The environment for both tests was controlled by the participant for location and lighting. RESULTS: Similar sensitivity scores were obtained between testing modalities in both the right (n = 28 participants; Wilcoxon match-paired signed rank [SR], p=0.7) and left eyes (n = 28 participants; Wilcoxon match-paired SR, p=0.7). In addition, similar test-retest scores were found for VR (n = 19 participants; Wilcoxon match-paired SR, p=1.0) or in-office (n = 19 participants; Wilcoxon match-paired SR, p=1.0) tests. Virtual reality Pelli-Robson results correlated well with in-office test results in variably diseased participants (n = 14 eyes from 7 participants, R2 = 0.93, p<0.0001). CONCLUSIONS: In this pilot trial, we demonstrated that VR Pelli-Robson measurements of corrected vision align with those of in-office modalities, suggesting that this may be a reliable method of implementing this test in a more interactive and accessible manner.

Study of stereopsis using a depth sensation detection platform equipped with computer vision technology (DALE3D).

BACKGROUND AND OBJECTIVES: The invention described herein is a prototype based on computer vision technology that measures depth perception and is intended for the early examination of stereopsis. MATERIALS AND METHODS: The prototype (software and hardware) is a depth perception measurement system that consists on: (a) a screen showing stereoscopic models with a guide point that the subject must point to; (b) a camera capturing the distance between the screen and the subject's finger; and (c) a unit for recording, processing and storing the captured measurements. For test validation, the reproducibility and reliability of the platform were calculated by comparing results with standard stereoscopic tests. A demographic study of depth perception by subgroup analysis is shown. Subjective comparison of the different tests was carried out by means of a satisfaction survey. RESULTS: We included 94 subjects, 25 children and 69 adults, with a mean age of 34.2 ± 18.9 years; 36.2 % were men and 63.8 % were women. The DALE3D platform obtained good repeatability with an interclass correlation coefficient (ICC) between 0.94 and 0.87, and coefficient of variation (CV) between 0.1 and 0.26. Threshold determining optimal and suboptimal results was calculated for Randot and DALE3D test. Spearman's correlation coefficient, between thresholds was not statistically significant (p value > 0.05). The test was considered more visually appealing and easier to use by the participants (90 % maximum score). CONCLUSIONS: The DALE3D platform is a potentially useful tool for measuring depth perception with optimal reproducibility rates. Its innovative design makes it a more intuitive tool for children than current stereoscopic tests. Nevertheless, further studies will be needed to assess whether the depth perception measured by the DALE3D platform is a sufficiently reliable parameter to assess stereopsis.

Reliability of self-measurement of visual acuity in AMD patients with two electronic devices based on the ETDRS chart: A randomized study.

INTRODUCTION: Age-related macular degeneration (AMD) requires continuous visual acuity (VA) monitoring, increasing the burden on the health care system. Self-measurement VA tests are available on various devices. However, none of them have been based on an internationally validated benchmark chart, such as that of the Early Treatment Diabetic Retinopathy Study (ETDRS). The goal of this study was to assess the reliability of two digitized ETDRS charts adapted to two electronic devices for self-measurement of VA. MATERIAL AND METHODS: A prospective, single-center, 1:1 randomized, two-arm, parallel group trial was conducted. The main objective was to compare VA variation as conventionally measured on a 4-m ETDRS chart versus self-measured with digitized ETDRS charts in patients treated for AMD. At each visit, conventional measurement and patient self-measurement, either on a computer at 80-cm (arm 1) or on a tablet at 40-cm (arm 2), were performed. RESULTS: Eighty patients were included (25 men, 55 women, mean age 81.3±7.4 years). No significant differences were observed between VA variation, conventionally measured and self-measured on a computer (arm 1; P=0.914) or tablet (arm 2; P=0.913). CONCLUSION: These results confirm the reliability of these two methods for self-measurement of VA, and will lead to the development of a wider "telemedicine" project extended to self-measurement of VA in various pathologies.

Effect of different screen brightness and devices on online visual acuity test.

PURPOSE: This study aimed to study the difference in test results of online visual acuity (VA) test under different devices and screen brightness conditions and to compare online VA test with Early Treatment Diabetic Retinopathy Study (ETDRS). METHODS: Healthy volunteers with the best corrected VA of 0.0 LogMAR or higher were recruited. VAs under ETDRS were tested first, and then online VA test (the Stanford Acuity Test, StAT) visual acuities using iPad Air2 and Microsoft Surface pro4 under 50% and 100% screen brightness were performed. The VA results and the testing times were compared between different devices and screen brightness conditions. RESULTS: A total of 101 eyes were included in this study. The VA results measured by the StAT were better than those of ETDRS. The VA results measured at 100% screen brightness were better than those of 50% brightness (mean difference, 0.013 logMAR at most, less than 1 letter); the VA results measured by iPad Air2 were better than those of Surface pro4 (mean difference, -0.009 logMAR at most, less than 1 letter). Significantly less time was spent on VA testing under StAT than that under ETDRS. CONCLUSION: The impact of screen brightness and the device on the VA results generated by online VA tests was clinically insignificant. In addition, online VA tests are found to be reliable and more time efficient than ETDRS.

Improving Access to Eye Care in Rural Communities: PocDoc's Web-Based Visual Acuity Screening Tool.

Objective: Visual acuity (VA) testing is crucial for early intervention in cases of visual impairment, especially in rural health care. This study aimed to determine the potential of a web-based VA test (PocDoc) in addressing the unique health care needs of rural areas through the comparison in its effectiveness against the conventional VA test in identifying visual impairment among an Indian rural population. Methods: Prospective comparative study conducted in December 2022 at a tertiary referral eye care center in central India. We evaluated all patients with the PocDoc VA tests using three device types, and the conventional VA test. Bland-Altman plot (BAP) compared PocDoc and conventional VA tests. Fisher's exact tests evaluated associations between categorical parameters. Kruskal-Wallis tests followed by post hoc Dunn's tests identified association between categorical parameters and numerical parameters. Results: We evaluated 428 patients (792 measurements of VA) with mean age 36.7 (±23.3) years. PocDoc resulted in slightly worse VA scores (mean logMAR: 0.345) than conventional (mean logMAR: 0.315). Correlation coefficient between the conventional and PocDoc logMAR VA values was rho = 0.845 and rho2 = 0.7133 (p = 6.617 × 10-215; adjusted p = 2.205 × 10-214). Most data points fell within the interchangeable range of ±0.32 on BAP. Difference between the two methods increased with higher logMAR values, indicating poorer agreement for worse VA scores. Conclusions: Identifying and addressing the unique health care needs of rural populations is critical, including access to appropriate and effective VA testing methods. Validating and improving VA testing methods can ensure early intervention and improve the quality of life for individuals with visual impairment.

Ametropia detection using a novel, compact wavefront autorefractor.

INTRODUCTION: Despite the well-known reproducibility issues of subjective refraction, most studies evaluating autorefractors compared differences between the device and subjective refraction. This work evaluated the performance of a novel handheld Hartmann-Shack-based autorefractor using an alternative protocol, which considered the inherent variability of subjective refraction. METHODS: Participants underwent an initial measurement with a desktop autorefractor, two subjective refractions (SR1 and SR2) and a final measurement with the QuickSee Free (QSFree) portable autorefractor. Autorefractor performance was evaluated by comparing the differences between the QSFree and each of the subjective refractions with the difference between the subjective refractions (SR1 vs. SR2) using Bland-Altman analysis and percentage of agreement. RESULTS: A total of 75 subjects (53 ± 14 years) were enrolled in the study. The average difference in the absolute spherical equivalent (M) between the QSFree and the SR1 and SR2 was ±0.24 and ±0.02 D, respectively, that is, very similar or smaller than the SR1 versus SR2 difference (±0.26 D). Average differences in astigmatic components were found to be negligible. The results demonstrate that differences between QSFree and both subjective refractions in J0 and J45 were within ±0.50 D for at least 96% of the measurements. The limits of agreement (LOAs) of the differences between QSFree and SR1, as well as QSFree and SR2, were higher than those observed between SR1 and SR2 for M, J0 and J45 . CONCLUSIONS: A protocol was designed and validated for the evaluation of a refractive device to account for the variability of subjective refraction. This protocol was used to evaluate a novel portable autorefractor and observed a smaller difference between the device and subjective refractions than the difference between the two subjective refraction measurements in terms of mean bias error, although the standard deviation was higher.

Comparison of Eye Tracking and Teller Acuity Cards for Visual Acuity Assessment in Pediatric Cortical/Cerebral Visual Impairment.

PURPOSE: To compare eye tracking and Teller acuity cards (TAC) for assessment of visual acuity in children with cortical, or cerebral, visual impairment (CVI). DESIGN: Reliability and validity study. METHODS: We recruited 41 children with CVI from a single academic pediatric neuro-ophthalmology clinic. All children performed eye tracking to measure visual acuity, and 26 children completed TAC assessment by a masked examiner. Additionally, 2 pediatric neuro-ophthalmologists graded visual behavior using the 6-level Visual Behavior Scale (VBS). Eye tracking and TAC were performed at baseline and at 1 month. Test-retest reliability of eye tracking and TAC were assessed using the intraclass correlation coefficient (ICC). Eye tracking and TAC visual acuities were correlated with one another and VBS scores using the Spearman correlation coefficient. RESULTS: Test-retest reliability was excellent for eye tracking measurement of visual acuity (ICC = 0.81, P < .0001). For pediatric CVI, TAC test-retest reliability was fair (ICC = 0.42, P = .04). There was a moderate correlation between eye tracking and TAC (r = 0.43, P = .03) and between TAC and VBS score (r = 0.50, P = .009), and a strong correlation between eye tracking grating acuity and VBS score (r = 0.72, P < .0001). CONCLUSIONS: In our cohort of children with CVI, grating acuity measured by eye tracking demonstrated higher test-retest reliability and stronger correlation with pediatric neuro-ophthalmologic assessment of visual behavior than Teller acuity. Objective determination of gaze direction by an eye tracking camera may be more accurate than human assessment in this population. Future research is needed to determine the optimal methods of longitudinal assessment of visual function and functional vision in children with CVI.

Red and green defocus curves and duochrome test in different age groups.

PURPOSE: To compare the eye defocus curves (DCs) obtained with stimuli on red, green, and white backgrounds and to investigate the applicability of the duochrome test (DT) in different age groups. METHODS: 12 elderly (ELD: 59.3 ± 3.9 years) and 8 young (YG: 22.1 ± 1.1 years) subjects were recruited. An optometric assessment with the DT was carried out to obtain the subjective refraction at distance. DCs at distance on green, white, and red backgrounds were measured and the following parameters were deduced: dioptric difference between red-green, green-white, red-white focal positions (minima of the DCs), best corrected visual acuity (BCVA), and widths of the DCs for red, green, and white. RESULTS: The DC difference between the green-white focal positions (mean ± standard deviation) was -0.12±0.17 diopters (D) (ELD, p= 0.012) and -0.11±0.12 D (YG, p= 0.039), while the red-white difference was not statistically significant. The DC red-green difference was 0.20±0.16 D (ELD, p= 0.002) and 0.18±0.18 D (YG, p = 0.008). The ELD BCVA with green background was significantly worse than BCVA with red (p = 0.007) and white (p = 0.007). The mean value of the DC's width in ELD for green (1.01±0.36 D) was higher than for red (0.77±0.21 D) and for white (0.84±0.35 D), but with no statistical significance. CONCLUSION: Both age groups showed a slight focusing preference for red when using white light. Moreover, ELD showed a worse BCVA with a green compared to a red background. Despite these results deduced by DC analyses, these aspects do not compromise the possibility of using the DT in clinical practice both in the young and in the elderly. Furthermore, the difference of about 0.20 D between red-green DC in both groups confirms the clinical appropriateness of the widespread use of 0.25 D step as the standard minimum difference in power between correcting lenses.

OKN-Fast: Objective visual acuity threshold measurement using the optokinetic response.

Visual acuity (VA) is the gold-standard measure for the assessment of visual function, but it is challenging to obtain in non-verbal adults and young children. We present OKN-Fast, an objective, automated method for estimation of VA using a reflexive eye movement called optokinetic nystagmus (OKN) that does not require a verbal response from the patient (VA-OKN). We tested the method in a cohort of healthy adults (n=12) with good vision, who were also blurred using a lens. On average OKN-Fast reduced the number of trials needed to determine threshold by half, as compared to a gold standard trial-by-trial assessment. The VAs determined by OKN and ETDRS were similar when blurred (no statistically significant difference). However, a significant bias of logMAR 0.2 was observed for the good vision condition. VA-OKN was highly repeatable with limits of agreement (LOA) similar to those found for ETDRS charts when blurred. However, this VA-OKN was only moderately correlated with VA measured using a ETDRS chart (r2 = 0.55). These results suggest that further optimization is warranted.Clinical Relevance- This work provides an automated approach for the estimation of visual acuity in non-verbal populations such as young children or non-verbal adults.