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

Abstract

PurposeTo evaluate two builds of the digital grating acuity test, “Peekaboo Vision” (PV), in young (6–60 months) populations in two hospital settings (Malawi and United Kingdom).MethodsStudy 1 evaluated PV in Blantyre, Malawi (N = 58, mean age 33 months); study 2 evaluated an updated build in Glasgow, United Kingdom (N = 60, mean age 44 months). Acuities were tested-retested with PV and Keeler Acuity Cards for Infants (KACI). Bland-Altman techniques were used to compare results and repeatability. Child engagement was compared between groups. Study 2 included test-time comparison.ResultsStudy 1 (Malawi): The mean difference between PV and KACI was 0.02 logMAR with 95% limits of agreement (LoA) of 0.33 to 0.37 LogMAR. On test-retest, PV demonstrated 95% LoA of −0.283 to 0.198 logMAR with coefficient of repeatability (CR) 0.27. KACI demonstrated 95% LoA of −0.427 to 0.323 logMAR, and larger CR was 0.37. PV evidenced higher engagement scores than KACI (P = 0.0005). Study 2 (UK): The mean difference between PV and KACI was 0.01 logMAR; 95% LoA was −0.413 to 0.437 logMAR. Again, on test-retest, PV had narrower LoA (−0.344 to 0.320 logMAR) and lower CR (0.32) versus KACI, with LoA −0.432 to 0.407 logMAR, CR 0.42. The two tests did not differ in engagement score (P = 0.5). Test time was ∼1 minute shorter for PV (185 vs. 251 s, P = 0.0021).ConclusionsPV gives comparable results to KACI in two pediatric populations in two settings, with benefits in repeatability indices and test duration.Translational RelevanceLeveraging tablet technology extends reliable infant acuity testing to bedside, home, and rural settings, including areas where traditional equipment cannot be financed.

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

“…Clinical infant vision tests have not changed for decades, 16 , 17 using a printed surface with the ageing and fading properties of paper and ink. The evolution of digital display technologies and their use for vision testing 1 , 2 , 6 , 7 , 18 – 20 is likely to continue and to require regulatory compliance to include photometric standards.…”

“…For the PV test, a two-target rather than four-target, setting 2 , 7 was selected to match the printed tests and to limit confounding influence relating to the number of possible positions of the target.…”

“…Uniformity was calculated from the maximum (L white max ) and minimum luminance of white (L white min ) for each test and lighting condition as L white min L white max (2) Compliance of overall luminance with International Council of Ophthalmology luminance…”

“…Most acuity tests for infants and young children use preferential looking methods with high contrast targets on an isoluminant grey background: if the target is perceptible, infants tend to give behavioral cues such as looking toward the target preferentially. This method under-pins printed tests ( 1,2 (Figs. 1A-C).…”

“…This method underpins printed tests (Teller Acuity Cards, first commercial version [TAC - Vistech Consultants Inc. Ohio, USA, batch no. 1277], Keeler Acuity Cards for Infants [KACI - Keeler, Windsor, UK], Lea Paddles [LP - Lea-Test Ltd and Good-Lite, Elgin, IL]), and a tablet-based digital acuity test, Peekaboo Vision (PV - Scottish Health Innovations Ltd, Clydebank, UK) 1 , 2 ( Figs. 1 A–C).…”