Reliability and validity of an automated computerized visual acuity and stereoacuity test in children using an interactive video game

Endpoints for clinical trials in ophthalmology

With the identification of novel targets, the number of interventional clinical trials in ophthalmology has increased. Visual acuity has for a long time been considered the gold standard endpoint for clinical trials, but in the recent years it became evident that other endpoints are required for many indications including geographic atrophy and inherited retinal disease. In glaucoma the currently available drugs were approved based on their IOP lowering capacity. Some recent findings do, however, indicate that at the same level of IOP reduction, not all drugs have the same effect on visual field progression. For neuroprotection trials in glaucoma, novel surrogate endpoints are required, which may either include functional or structural parameters or a combination of both. A number of potential surrogate endpoints for ophthalmology clinical trials have been identified, but their validation is complicated and requires solid scientific evidence. In this article we summarize candidates for clinical endpoints in ophthalmology with a focus on retinal disease and glaucoma. Functional and structural biomarkers, as well as quality of life measures are discussed, and their potential to serve as endpoints in pivotal trials is critically evaluated.

Development and validation of a new method for visual acuity assesment on tablet in pediatric population: eMOVA test

BACKGROUND

Amblyopia is a major public health concern. Its screening and management require reliable methods of visual acuity assessment. New technologies offer nowadays many tests available on different app stores for smartphone or tablet but most of them often lack of scientific validation for a medical use. The aim of our study was to attempt validating a tablet-based near visual acuity test adapted to the pediatric population: the eMOVA test (electronic Measurement Of Visual Acuity) by comparing visual acuity measured with more conventional test.

METHODS

A cohort of 100 children aged 3 to 8 attending the ophthalmic-pediatric for eye examination between September 2016 and June 2017 were included in the study. Near visual acuity was assessed on participants using both the eMOVA test and a Standard test (Rossano-Weiss test). Duration of each test, its comprehension, its acceptability and the attention of the child during the test was also investigated.

RESULTS

The eMOVA test overestimated near visual acuity by 0.06 logMAR. This difference, statistically significant, was not clinically relevant. The duration of the eMOVA test was longer than the reference test, but less discomfort and preferred by children and their parents compared to standard tests.

CONCLUSION

The eMOVA test appears as a reliable test to assess near visual acuity in children. By its portability and efficiency, this application proved to be a relevant tool to be used for children eye examination in daily routine at the hospital.

Screening for Stereopsis Using an Eye-Tracking Glasses-Free Display in Adults: A Pilot Study

Purpose:

To explore the feasibility and repeatability of a novel glasses-free display combined with random-dot stimulus and eye-tracking technology for screening stereopsis in adults.

Methods:

A total of 74 patients aged 18–44 years were recruited in this study (male: female, 32:42), including 33 patients with high myopia [≤ -6.0 diopters (D)] and 41 patients with moderate-to-low myopia (>-6.0 D). Stereopsis was measured using glasses-free, polarized, and Titmus stereotests. All patients completed a visual fatigue questionnaire after the polarized stereotest and glasses-free test. Kendall's W and Cohen's Kappa tests were used to evaluate repeatability and consistency of the glasses-free stereotest.

Results:

The stereotest results using the glasses-free monitor showed strong repeatability in the three consecutive tests (W = 0.968, P < 0.01) and good consistency with the polarized stereotest and Titmus test results (vs. polarization: Kappa = 0.910, P < 0.001; vs. Titmus: Kappa = 0.493, P < 0.001). Stereopsis levels of the high myopia group were significantly poorer than those of the moderate-to-low myopia group in three stereotest monitors (all P < 0.05). There was no significant difference in visual fatigue level between the polarized and the glasses-free display test (P = 0.72). Compared with the polarized test, 56.76% of patients preferred the glasses-free display and found it more comfortable, 20.27% reported both tests to be acceptable.

Conclusions:

In our adult patients, the new eye-tracking glasses-free display system feasibly screened stereopsis with good repeatability, consistency, and patient acceptance.

Effect of Luminance and Contrast Variation on Stereoacuity Measurements Using Smartphone Technology

Owing to the limitations of printed stereoacuity tests, the effects of luminance and contrast on stereopsis have not yet been sufficiently investigated, despite its important implications in designing stereoacuity measuring instruments, particularly for electronic devices. A stereopsis measurement system was established using two 4 K smartphones and a phoropter to evaluate the effects of luminance and contrast variations on the stereoacuity test. Seventeen young subjects with normal visual acuity and stereopsis were recruited. Two types of test symbols, contour-based and random-dot-based, were used in the experiment. Four series tests were established with different maximum brightness values, including 240 lux, 120 lux, 60 lux, and 30 lux. Each series test contained 19 pages with different contrasts between 95% and 5% and was calculated using the Michelson contrast formula. No significant difference was found for both contour-based and random-dot-based stereograms in any of the contrast groups with different maximum brightness. Similarly, no significant difference was found between contour-based and random-dot-based patterns under different contrasts of above 35%. As the contrast decreased below 30%, the stereopsis was significantly better in the contour-based pattern than in the random-dot-based pattern for some degrees of contrast. The luminance and contrast of the digital display are not critical factors for stereoacuity under normal circumstances. This implies that a standard monitor with a certain 3D technology can be used to measure the stereoacuity threshold without calibrating the luminance and contrast.

Influence of Lenslet Configuration on Short-Term Visual Performance in Myopia Control Spectacle Lenses

Purpose: This study aimed to evaluate short-term visual performance and optical quality of three different lenslet configurations on myopia control spectacle lenses.

Materials and Methods: This study utilized a cross-over design. Distance visual acuity (VA) was measured in 50 myopic children; contrast sensitivity (CS) was measured in 36 myopic children. For each test, four spectacle lenses were evaluated in a random order: single-vision lens (SVL), lens with concentric rings of highly aspherical lenslets (HAL), lens with concentric rings of slightly aspherical lenslets (SAL), and lens with honeycomb configuration of spherical lenslets (HC). The modulation transfer function (MTF) and MTF area (MTFa) were used to determine optical quality. All tests were performed monocularly on the right eye with full correction.

Results: HAL and SAL had larger MTFa than HC. VA in lenses with lenslets was significantly reduced compared to SVL (all p < 0.01). The reduction in VA was worse with HC than with SAL (p = 0.02) and HAL (p = 0.03); no effect of lenslet asphericity was found (p > 0.05). VA changes induced by lenslets showed no correlation with spherical equivalent refraction (all p > 0.05) and were weakly positively associated with age for SAL (r = 0.36, p = 0.01) and HC (r = 0.31, p = 0.03), but not for HAL (p = 0.30). The area under the log contrast sensitivity function (AULCSF) decreased with HAL and HC (all p < 0.001) in all illumination levels, and AULCSF with HAL was higher than that with HC in a photopic condition (1.17 ± 0.10 vs. 1.10 ± 0.13, p = 0.0004). The presence of lenslets did not affect CS at 3 cycles per degree (cpd) (p = 0.80). At 6 to 18 cpd, CS was significantly reduced by HAL and HC (all p < 0.05), but not SAL (p > 0.05) compared to SVL. At high spatial frequencies (>12 cpd) both SAL and HAL reduced CS significantly less than HC (all p < 0.01).

Conclusion: Short-term visual performance was minimally impaired by looking through the lenslet structure of myopia control spectacle lenses. Concentric rings with aspherical lenslets had a significantly lower impact on both VA and CS than honeycomb configuration with spherical lenslets.

A new visual acuity test on touchpad for vision screening in children

AIM

To validate a visual acuity (VA) test application on touchpad in the screening of pediatric population by comparing VA results obtained with conventional tests.

METHODS

A cohort of 101 patients, 44 girls and 57 boys with a median of 6.5 years old (3-10 years of age), presenting for eye examinations in Ophthalmology Department (Strasbourg, France) between November 1^st, 2018, and February 1^st, 2019 were enrolled. Monocular and binocular VA testing was performed on the subject using both a standard test and the touchpad application (Monoyer, "E" or, Pigassou depending of children's capacities). Patients were excluded if they were physically or mentally unable to use the touchpad. The duration of each tests, the painfulness, the comprehension, the attention of children during the test and test's preferences were also evaluated.

RESULTS

There was a good linear correlation and intra-class correlation coefficient [ICC=0.50 (0.34, 0.64) for binocular acuity, 0.74 (0.64, 0.82) for right eyes and 0.525 (0.37, 0.66) for left eye]. The standard errors of measurement were very low (0.08, 0.05, 0.08 for binocular VA, right eyes VA and left eyes VA, respectively). There was no difference between two tests for right eye (P=0.126), left eye (P=0.098) and binocular acuity (P=0.085). Non inferiority was proved for all binocular [-0.06 (-0.09, -0.03)], right eye [-0.04 (-0.07, -0.01)] and left eye [-0.06 (-0.09, -0.02)] VA. The sensitivity and specificity, which correspond to the ability for our app to detect amblyopia, were 92% and 80% respectively.

CONCLUSION

Our touchpad application represents an efficient and valid test of VA in children with a high specificity to detect visual impairment.

The difference in stereoacuity testing: contour-based and random dot-based graphs at far and near distances

Background

Different methods to test stereopsis lead to different results. The aim of this study was to investigate the difference between stereoacuity tests using contour-based and random dot-based graphs at far and near distances.

Methods

Thirty participants with normal visual acuity and stereopsis were recruited. Laptop equipment 3D shutter glasses were used to test distance stereoacuity and two 4K smartphones were used to test near stereoacuity with contour-based and random dot-based graphs.

Results

No significant difference was found between contour-based and random-dot graphs regardless of the distance. Similarly, no significant difference between far and near distance was found for contour-based or random-dot graphs (Wilcoxon signed-rank test: P values were all >0.05). There was a high level of agreement between the methods using Bland-Altman statistical analysis.

Conclusions

In a population with normal stereopsis, the stereoacuity is stable regardless of the test graphs used (contour-based or random-dot based) or the test distance (far or near).

Effect of chromatic contrast on stereoacuity measurement with computer-aided three-dimensional technology

Background

Various measurement tools are utilized to detect the stereopsis threshold in the clinic, but seldom of these involves chromatic information. Incorporating colorful elements into computer-aided, three-dimensional (3D) evaluation systems could help the tests appear more vivid and attractive. The aim of this study was to clarify the effect of different chromatic pair stereo targets on the stereoacuity result.

Methods

A total of 17 subjects with visual acuity in each eye of at least 0 logarithmic minimum angle of resolution (logMAR) and a stereoacuity of at least 32 second of arc (arcsec) were recruited. A 3D laptop with liquid crystal shutter glasses was used for evaluating stereoacuity. Thirteen pages were set including seven maximum color contrast pages and six isoluminant color contrast pages.

Results

In maximum color contrast pair, no significant difference was found among all seven experiments [six test groups and one reference group, one-way analysis of variance (ANOVA) test, F=0.995, P=0.493]. There was also no significant difference among the isoluminant color contrast pairs (six test groups, one-way ANOVA test, F=0.873, P=0.644). Paired t-test was used for comparing the data between the same hue series in the maximum color contrast pair vs. the isoluminant color contrast pair, and significant differences were found in all six pairs (P<0.001).

Conclusions

Adding chromatic factors to the stereo test is practical to evaluate stereopsis.

ASTEROID: A New Clinical Stereotest on an Autostereo 3D Tablet

Purpose

To describe a new stereotest in the form of a game on an autostereoscopic tablet computer designed to be suitable for use in the eye clinic and present data on its reliability and the distribution of stereo thresholds in adults.

Methods

Test stimuli were four dynamic random-dot stereograms, one of which contained a disparate target. Feedback was given after each trial presentation. A Bayesian adaptive staircase adjusted target disparity. Threshold was estimated from the mean of the posterior distribution after 20 responses. Viewing distance was monitored via a forehead sticker viewed by the tablet's front camera, and screen parallax was adjusted dynamically so as to achieve the desired retinal disparity.

Results

The tablet must be viewed at a distance of greater than ∼35 cm to produce a good depth percept. Log thresholds were roughly normally distributed with a mean of 1.75 log₁₀ arcsec = 56 arcsec and SD of 0.34 log₁₀ arcsec = a factor of 2.2. The standard deviation agrees with previous studies, but ASTEROID thresholds are approximately 1.5 times higher than a similar stereotest on stereoscopic 3D TV or on Randot Preschool stereotests. Pearson correlation between successive tests in same observer was 0.80. Bland-Altman 95% limits of reliability were ±0.64 log₁₀ arcsec = a factor of 4.3, corresponding to an SD of 0.32 log₁₀ arcsec on individual threshold estimates. This is similar to other stereotests and close to the statistical limit for 20 responses.

Conclusions

ASTEROID is reliable, easy, and portable and thus well-suited for clinical stereoacuity measurements.

Translational Relevance

New 3D digital technology means that research-quality psychophysical measurement of stereoacuity is now feasible in the clinic.

Recognition acuity in children measured using The Auckland Optotypes

PURPOSE

Sloan letters displayed by the Electronic Visual Acuity (EVA) system are the gold standard for recognition acuity measurement in research settings. However, letters are not always appropriate for children. The Auckland Optotypes (TAO) are a new, open-access set of 10 pictograms available in regular and vanishing formats. We sought to assess feasibility of using both formats of TAO for measuring visual acuity (VA) in children using a Bayesian adaptive staircase, in a community setting.

METHODS

We tested 121 children (5-12 years old) with both formats of TAO, a handheld flipchart vision screener (Parr vision test), as well as the gold standard EVA. We measured feasibility of the three comparison tests in three ways. First, using limits of agreement (LoA) with EVA, second, calculating area under the receiver operating characteristic curve (AUC), and finally, investigating trial-by-trial responses.

RESULTS

Agreement between tests was within test-retest reliability of EVA measures (LoA_{TAO regular}  = ±0.14, LoA_{TAO vanishing}  = ±0.15, LoA_{P arr}  = ±0.16 logMAR). TAO tests were highly effective at identifying children with vision impairment (AUC_{TAO regular}  = 0.96, AUC_{TAO vanishing}  = 0.95), whereas Parr was less effective (AUC_{P arr}  = 0.82). In 5-6 year old children there was an enhanced advantage of TAO (AUC_{TAO regular}  = 0.97, AUC_{TAO vanishing}  = 0.98) over Parr (AUC_{P arr}  = 0.75). Although each child completed 16 trials, approximately 10 trials were sufficient to achieve excellent LoA, and six trials sufficient for accurate screening.

CONCLUSION

Threshold VA assessment and vision screening are feasible using both vanishing and regular formats of TAO.

Stereoacuity measurement using a phoropter combined with two 4K smartphones

PURPOSE

To evaluate stereoacuity using a combination of a phoropter and two 4K smartphones.

METHODS

A stereopsis measurement system was established using a phoropter (Topcon VT-10) and two Sony 4K smartphones (Sony Xperia Z5 Premium Dual E6883). A total of 154 subjects (69 children and 85 adults) were enrolled for evaluation using this system and subsequent comparison with the Fly Stereo Acuity test.

RESULTS

There was a high level of agreement between the two methods using Bland-Altman statistical analysis (children group, 95 per cent limits of agreement ±0.14 log arcseconds [arcsec]; adult group, 95 per cent limits of agreement ±0.13 log arcsec).

CONCLUSION

The closely spaced pixels of a 4K smartphone display enable measurement of stereoacuity at a relatively short distance. The flexibility and versatility of the mobile test system are likely to be useful in clinical practice.

Automated Measurement of Visual Acuity in Pediatric Ophthalmic Patients Using Principles of Game Design and Tablet Computers

PURPOSE

To report on the utility of a computer tablet-based method for automated testing of visual acuity in children based on the principles of game design. We describe the testing procedure and present repeatability as well as agreement of the score with accepted visual acuity measures.

DESIGN

Reliability and validity study.

METHODS

Setting: Manchester Royal Eye Hospital Pediatric Ophthalmology Outpatients Department.

PATIENT POPULATION

Total of 112 sequentially recruited patients.

INTERVENTION

For each patient 1 eye was tested with the Mobile Assessment of Vision by intERactIve Computer for Children (MAVERIC-C) system, consisting of a software application running on a computer tablet, housed in a bespoke viewing chamber. The application elicited touch screen responses using a game design to encourage compliance and automatically acquire visual acuity scores of participating patients. Acuity was then assessed by an examiner with a standard chart-based near ETDRS acuity test before the MAVERIC-C assessment was repeated.

MAIN OUTCOME MEASURE

Reliability of MAVERIC-C near visual acuity score and agreement of MAVERIC-C score with near ETDRS chart for visual acuity.

RESULTS

Altogether, 106 children (95%) completed the MAVERIC-C system without assistance. The vision scores demonstrated satisfactory reliability, with test-retest VA scores having a mean difference of 0.001 (SD ±0.136) and limits of agreement of 2 SD (LOA) of ±0.267. Comparison with the near EDTRS chart showed agreement with a mean difference of -0.0879 (±0.106) with LOA of ±0.208.

CONCLUSIONS

This study demonstrates promising utility for software using a game design to enable automated testing of acuity in children with ophthalmic disease in an objective and accurate manner.

Evaluating stereoacuity with 3D shutter glasses technology

Background

To determine the stereoacuity threshold with a 3D laptop equipped with 3D shutter glasses, and to evaluate the effect of different shape and size of test symbols and different type of disparities to stereoacuity.

Methods

Thirty subjects with a visual acuity in each eye of at least 0 logMAR and a stereoacuity of at least 32 arcsec (as assessed in Fly Stereo Acuity Test) were recruited. Three target symbols—tumbling "E", tumbling "C", and "□"—were displayed, each with six different sizes representing a visual acuity ranging from 0.5 to 0 logMAR when tested at 4.1 m, and with both crossed and uncrossed disparities. Two test systems were designed - fixed distance of 4.1 m and one for variable distance. The former has disparities ranging from 10 to 1000 arcsec. Each subject completed 36 trials to investigate the effect of different symbol sizes and shapes, and disparity types on stereoacuity. In the variable distance system, each subject was tested 12 times for the same purposes, both proximally and distally (the point where the 3D effect just appears and where it just disappears respectively), and the mean value was calculated from the mean proximal and distal distances.

Results

No significant difference was found among the groups in the fixed distance test system (Kruskal-Wallis test; Chi-square = 29.844, P = 0.715). Similarly, no significant difference was found in the variable distance system (Kruskal-Wallis test; proximal: Chi-square = 5.687, P = 0.338; distal: Chi-square = 5.898, P = 0.316; mean: Chi-square = 6.152, P = 0.292).

Conclusions

Evaluating stereoacuity using this measurement system was convenient and effective. Changes in target shape and size and disparity types had no significant effect on stereoacuity. It would be helpful to choose optimal targets according to different purposes using computer-assisted 3D measurements.

Electronic supplementary material

The online version of this article (doi:10.1186/s12886-016-0223-3) contains supplementary material, which is available to authorized users.

Distance stereotesting using vision test charts for intermittent exotropia

Purpose

To assess the role of distance stereoacuity using the System Chart SC-1600 Pola (SC) to evaluate intermittent exotropia (IXT).

Methods

Stereoacuity testing was performed in 28 children with IXT and 25 age-matched control subjects using the SC test, the distance Randot stereotest for distance, and the Titmus stereotest for near stereoacuity. Ocular alignment control was defined using the revised Newcastle Control Score (NCS). The correlations between the stereotests and NCS were evaluated using Spearman’s correlation test.

Results

Distance stereoacuity was better in both groups when using the SC test than when using the distance Randot stereotest (median: patients with IXT, 90 arcsec and 400 arcsec; control, 60 arcsec and 100 arcsec; P<0.001 for both comparisons). The two test scores were not correlated in either group (IXT: r_s=−0.003, P=0.99; control: r_s=0.37, P=0.07). A positive correlation was found between the distance NCS and SC test scores (r_s=0.49, P=0.004) and the total NCS and SC test scores (r_s=0.49, P=0.004). However, no correlation was observed between any NCS and the distance Randot stereotest or Titmus stereotest scores.

Conclusion

Stereoacuity, as measured by the SC test, may be an objective measure of IXT control.