Testing Pediatric Acuity With an iPad: Validation of "Peekaboo Vision" in Malawi and the UK

Development of Automated Visual Acuity Measurement Using a Calibration-Free Eye-Tracking System

Purpose Infant vision assessment often relies on grating acuity; however, its objectivity and convenience must be improved. A calibration-free eye-tracking system, even in preverbal children, enables easy and precise gaze analysis. This pilot study aimed to develop a reliable automated monocular vision screening. Methods Participants (n=118) underwent a grating visual acuity test using the eye-tracking system. Correlations between the grating acuity, uncorrected visual acuity, and refractive error were analyzed across different cutoff values of fixation duration percentage. Results Strong correlations were found between the grating acuity and refractive error at 69% and 88% thresholds. Similar correlations with uncorrected visual acuity were noted at 70% and 89% thresholds. False-negatives around the 70% threshold were noted, indicating potential overestimation of acuity in cases of low visual acuity/high refractive error. Discussion The results highlight the feasibility of calibration-free eye-tracking system-based monocular vision screening with an optimal screening threshold of 90%.

Children's visual acuity tests without professional supervision: a prospective repeated measures study

BACKGROUND

Home visual acuity tests could ease pressure on ophthalmic services by facilitating remote review of patients. Home tests may have further utility in giving service users frequent updates of vision outcomes during therapy, identifying vision problems in an asymptomatic population, and engaging stakeholders in therapy.

METHODS

Children attending outpatient clinics had visual acuity measured 3 times at the same appointment: Once by a registered orthoptist per clinical protocols, once by an orthoptist using a tablet-based visual acuity test (iSight Test Pro, Kay Pictures), and once by an unsupervised parent/carer using the tablet-based test.

RESULTS

In total, 42 children were recruited to the study. The mean age was 5.6 years (range 3.3 to 9.3 years). Median and interquartile ranges (IQR) for clinical standard, orthoptic-led and parent/carer-led iSight Test Pro visual acuity measurements were 0.155 (0.18 IQR), 0.180 (0.26 IQR), and 0.300 (0.33 IQR) logMAR respectively. The iSight Test Pro in the hands of parents/carers was significantly different from the standard of care measurements (P = 0.008). In the hands of orthoptists. There was no significant difference between orthoptists using the iSight Test Pro and standard of care (P = 0.289), nor between orthoptist iSight Test Pro and parents/carer iSight Test Pro measurements (P = 0.108).

CONCLUSION

This technique of unsupervised visual acuity measures for children is not comparable to clinical measures and is unlikely to be valuable to clinical decision making. Future work should focus on improving the accuracy of the test through better training, equipment/software or supervision/support.

Measuring recognition visual acuity in young children - testability with the Waterloo Differential Acuity Test (WatDAT)

CLINICAL RELEVANCE

Visual acuity measurement is important for the detection and monitoring of eye disorders. Developing accurate and sensitive visual acuity tests suitable for young children is therefore desirable.

BACKGROUND

Recognition or form visual acuity (VA), which is measured with matching in children aged 3 years and up, is more sensitive for detecting visual deficits compared to resolution VA. The Waterloo Differential Acuity Test (WatDAT) is a proposed recognition VA test using the concept of identifying the "odd one out" among distractors. The WatDAT is expected to be cognitively easier than matching tests and therefore may be used in younger children. The purpose of this study is to investigate the testability of the WatDAT paradigm in children aged 12-36 months, and to determine the optimum format and number of distractors.

METHODS

Fifty-one typically-developing children aged 12-36 months participated in the study. Data for Patti Pics (PP) and Face targets (FT) were collected for formats with 3, 4 and 5 distractors. The targets were presented binocularly on a computer touch screen at 30 cm. The task was to touch the face among identical non-faces or a house among circles. Following initial training, there were 5 presentations for each distractor format. Testability was defined as correctly identifying at least 4/5 presentations and was also determined for uncrowded PP symbols using matching.

RESULTS

Of participants aged 18-36 months, 87% could perform the WatDAT PP targets with 3 distractors compared to 68% for the FT, while 48% could perform matching with PP. The testability for FT increased to 85% for children ≥22 months. Younger children showed lower testability. For the 3 distractor format, PP targets gave 9% testability in children 12 to <18 months, and FT gave a testability of 16% in children 12 to <22 months.

CONCLUSION

WatDAT testability is higher than matching VA tests. This indicates that the newly developed WatDAT has potential for measuring recognition VA in children 18 months and older.

Feasibility of measuring eye–hand coordination in children with developmental delay using Sanet Vision Integrator

Eye–hand coordination is a visuomotor task that enables one to look, localize, and touch objects. Eye–hand coordination is known to be poor in children with developmental delay. In this study, we assessed the feasibility of measuring eye–hand coordination task in children with developmental delay using Sanet Vision Integrator (SVI), a commercially available device. Children (age: 3–16 years) with developmental delay and their age-similar typically developing peers were enrolled. White circles (5.5°) on a black background were presented on the SVI touch screen monitor. Participants popped these circles by touching it. Reaction time, accuracy, and an overall performance score were computed. Participants could perform the task from 4 years of age and with visual acuity 20/400 (6/120) or better. This resulted in 85% (17/20) of children with developmental delay and 95% (19/20) of typically developing children completing the task. Children with developmental delay were significantly ( p < .001) less accurate (56%) and took longer (2.63 s) to complete the task when compared with their peers (accuracy = 93%, reaction time = 1.46 s). The overall performance score of children with developmental delay was also lower than their peers by a factor of 3.3. Eye–hand coordination performance can be measured and quantified with SVI. The quantification of speed and accuracy is possible and a unitary measure combining speed-accuracy can be computed. The task can be performed both by typically developing children and by children with developmental delay. Thus, it is feasible to measure eye–hand coordination using SVI. Such quantification will be useful for children undergoing interdisciplinary therapies for their medical conditions.

Grating acuity tests for infants, young children and individuals with disabilities: A review of recent advances

BACKGROUND

Accurate measurement of visual acuity is important in managing any ocular condition. Measuring visual acuity has always remained a challenge in infants, young children and individuals with disabilities who are unable to respond verbally. A variety of pediatric acuity tests that include both grating and recognition acuities have been described in the literature, some of which are outdated. This review paper aims to summarize the currently available and recently developed grating acuity tests that can be used for infants, young children and individuals with disabilities.

METHODS

A review of literature was carried out to identify tests that were currently available and recently developed. Additionally, search was also done on popular search engines and websites of companies. Tests identified were screened for availability and investigated for validity through published research in peer-reviewed journals.

RESULTS

A total of eight grating acuity tests were identified, out of which six of them were paper-based tests. The remaining two tests were app-based tests with established data for the typically developing pediatric cohort. The repeatability indices were available only for four grating acuity tests.

CONCLUSIONS

This review paper summarizes the basic features of the grating acuity tests and importantly, the parameters that determine the clinical utility of the tests such as the testability, acuity range, specific cohort studied, testing time and reliability indices. The paper also discusses the recent technological advancements in the field of acuity testing for the pediatric cohort and its comparisons with the conventional methods when available.

Too Many Shades of Grey: Photometrically and Spectrally Mismatched Targets and Backgrounds in Printed Acuity Tests for Infants and Young Children

Purpose

Acuity tests for infants and young children use preferential looking methods that require a perceptual match of brightness and color between grey background and target spatial average. As a first step in exploring this matching, this article measures photometric and colorimetric matches in these acuity tests.

Methods

The luminance, uniformity, contrast, and color spectra of Teller Acuity Cards, Keeler Acuity Cards for Infants, and Lea Paddles under ambient, warm, and cold lighting, and of grey-emulating patterns on four digital displays, were measured. Five normal adults' acuities were tested at 10 m observationally.

Results

Luminance and spectral mismatches between target and background were found for the printed tests (Weber contrasts of 0.3% [Teller Acuity Cards], -1.7% [Keeler Acuity Cards for Infants], and -26% [Lea Paddles]). Lighting condition had little effect on contrast, and all printed tests and digital displays met established adult test luminance and uniformity standards. Digital display grey backgrounds had very similar luminance and color whether generated by a checkerboard, vertical grating, or horizontal grating. Improbably good psychophysical acuities (better than -0.300 logMAR: (logarithm of the minimum angle of resolution)) were recorded from adults using the printed tests at 10 m, but not using the digital test Peekaboo Vision.

Conclusions

Perceptible contrast between target and background could lead to an incorrectly measured, excessively good acuity. It is not clear whether the luminance and spectral contrasts described here have clinically meaningful consequences for the target patient group, but they may be avoidable using digital tests.

Translational Relevance

Current clinical infant acuity tests present photometric mismatches that may return inaccurate testing results.

Automated Visual Acuity Evaluation Based on Preferential Looking Technique and Controlled with Remote Eye Tracking

OBJECTIVE

To establish an automated visual acuity test (AVAT) for infants, based on preferential looking technique and controlled with remote eye tracking. To validate the AVAT in a group of healthy children. To compare AVAT visual acuity (VA) values with corresponding VA values acquired with standard tests (ST).

METHODS

ST, adapted for age (Keeler Acuity Cards in preverbal children and LEA symbols in verbal children), was performed to obtain monocular VA in a group of 36 healthy children. During AVAT, 9 different stimuli with grating circles that matched spatial frequencies of 9 Keeler Acuity Cards (ranging between 0.29 and 14.5 cycles per degree) were projected on a screen. Three repetitions of each stimulus were shown during 9-s intervals, interchanging with an attention grabber. The remote eye tracker was used to evaluate the proportion of time a child spent looking at each grating circle compared to a homogeneous gray background that matched the grating stimuli in average luminance. From this proportion of time, child's binocular VA was evaluated.

RESULTS

Ninety-seven percent (35/36) of healthy children successfully completed ST and AVAT. There was an agreement between the results of an ST and AVAT, with Lin's concordance coefficient being 0.53 (95% CI = 0.31-0.72). A tendency was observed toward VA overestimation on AVAT for children with VA >0.4 logMAR on ST and toward VA underestimation on AVAT for children with VA ≤0.4 logMAR on ST.

CONCLUSIONS

AVAT requires a minimally skilled investigator. The evaluation of better eye monocular VA on ST and binocular VA on AVAT was comparable for healthy children.