Developing objective tests of eye movements and eye-hand coordination for application in amblyopia

Abstract

Amblyopia occurs in up to 5% of the normal population, and is a unilateral or (rarely) bilateral visual disorder that occurs during the critical period of brain development and produces deficits in visual function such as acuity and stereopsis, plus abnormalities in eye movement (EM) and eye-hand coordination (EHC). Previous approaches to the assessment of EM and EHC are limited and poorly developed for clinical use and research. In particular, they are subjective, require a high degree of skill, are time consuming or are costly.

The aim of this study was to develop novel tests of EM and EHC using simple computer-based objective tasks. These two tests (the Lee EM Test and Lee-Ryan EHC Test) were validated and used to examine differences in performance in normal, untreated amblyopic and treated-amblyopic vision under monocular and binocular viewing conditions in children and teenager/young adults.

The Lee EM Test was based on the â Northeastern State University College of Optometry (NSUCO) Testâ . In the Lee EM test, video recordings were made of individuals making saccadic and pursuit movements. Recordings were analysed regarding ability and accuracy of EM plus head and body movements on 5-point scales.

The Lee-Ryan EHC Test comprised an i-Pad® app and the involved the use of a stylus pen to trace 13 shapes of different degrees of difficulty. For each shape, time taken to complete the trace, number of errors, mean speed, x/y axis deviation and mean deviation are measured and automatically saved by a program on the iPad platform.

The EM testing revealed significant differences between normal, amblyopic and treated-amblyopic vision in both saccadic (p<0.05) and pursuit (p<0.05) movements. The biggest difference was significantly worse performance for amblyopes than normals for accuracy in both saccades and pursuits in monocular or binocular viewing conditions (p<0.0001).

For EHC, both children and teenager/adults with untreated amblyopia made significantly more errors (p<0.05) than those with normal vision. Notably, EHC in children with successfully treated amblyopia, performance was at an intermediate level.

This study has characterised and validated simple computer-based tasks assessing EM and EHC and demonstrated that these are effective in characterising differences in performance between normal and amblyopic vision in children and adults. The objectivity and simplicity of these tests may be applied in clinical research that examines/monitors visual-motor interactions (e.g., sports vision, visual-motor disorders that are developmental or after stroke).