New technologies in paediatric acuity assessment

Abstract

The present research has evaluated the utility of the computer tablet as a means to test vision in an infant population. The following points summarise the main findings: Regards the physical properties of mobile tablet computer with reference to National and International Standards for Chart Design: Photometric standards of luminance, contrast, and luminance uniformity are met more effectively by the range of iPads under test than by dedicated ETDRS (Early Treatment Diabetic Retinopathy Study) charts in active clinical use in a tertiary referral unit. The study met its aim of documenting the suitability of this mobile technology regards high contrast acuity standards, providing a practical guide to health care professionals working within eye care. These standards were then, where possible, extended to card-based infant vision tests. There are intrinsic advantages to digital platforms regards achieving a mean average luminance “grey” background relative to the black and white values of composite foreground gratings. There is marked heterogeneity across traditional card-based platforms regards luminance and contrast measurements relating to black, white and grey components. These observations informed the design of a prototype build of a computer-tablet based infant acuity test, peekaboo vision (PVb1). This build was evaluated in a blurred adult cohort. PVb1 performed well across a range of artificially degraded acuities, with observed potential benefits regards test-retest repeatability. PVb1 was then evaluated in an infant population in rural Africa in a pilot study (Study 1). A subsequent formal build (PVi) was evaluated in a UK setting with a similar methodology (Study 2), comparing with Keeler Acuity Cards for Infants (KACI) as the reference standard. Across Studies 1 and 2, the mean difference between reference standard and digital version was modest (-0.03 to 0.01), with notable differences in upper and lower limits of agreement in favour of the digital platform (exhibiting narrower LoA). Peekaboo Vision evidenced improved repeatability than KACI: coefficients of repeatability were 0.27 for Peekaboo Vision versus 0.37 for Keeler cards in study 1, and 0.32 for Peekaboo Vision versus 0.42 for Keeler cards in study 2. The mean time-to-test was over 1 minute shorter (by 26%) for Peekaboo Vision than for Keeler cards (p= 0.0021)