Construction and Validation of Anaglyph dichoptic vision chart and its application in detecting suppression in paediatric eye screening.

Amblyopia being the most common cause of monocular vision loss in children, is defined as decreased best-corrected visual acuity (VA) in one, or less frequently both eyes, in the absence of any obvious structural anomalies or ocular disease.

The gold standard for amblyopia screening is visual acuity testing and most vision screening programs still rely on visual acuity charts as their primary screening test for amblyopia. Visual acuity testing requires cooperation from the children and needs to be done in each eye separately. It is subject to errors depending on if children have memorized the charts, peeps from other eye while testing, and so on.

Suppression of an eye is a subconscious adaptation by a person’s brain to eliminate double vision by ignoring all or part of the image of one of the eyes, and is an important component of amblyopia. The currently options available commercially for assessing suppression are the Four base out prism test, Worth Four dot test, Polarized four dot test.

Most commercial methods of testing suppression measure only foveal or central suppression at one test distance.Also,current clinical tests for suppression tend to verify the presence or absence of suppression rather than giving a quantitative measurement of the degree of suppression.

In this study, we aim to develop a new chart based on dichoptic principles thus detecting suppression and quantifying it by measuring the size of suppression scotoma,testing mono-ocular visual acuity binocularly and validating it with standard ETDRS chart which is used for screening amblyopia in school going children currently.