Purpose: Normal development of stereopsis is based on good binocular vision and might get disrupted by a number of factors like refractive errors, amblyopia and/or strabismus. The study was undertaken with the aim to analyze impact of refractive errors with and without amblyopia and/or strabismus on stereopsis in school going children of rural Haryana.
Methods: Subjects in the age group of 5-15 years without any organic disorders were included over a period of two months. Cycloplegic refraction was undertaken and stereo acuity was demonstrated on Titmus fly stereogram under standard conditions. Subjects were divided into three groups: Plain refractive errors (isometropic or anisometropic) (group-I), subjects with amblyopia (group-II) and with strabismus (group-III). Further subgroups were made as per the type of refractive error.
Results: Subjects in group-I retained better stereo acuity as compared to group-II (P<0.01) and group-III (p<0.01). Isometropes in group-I retained better stereo acuity as compared to anisometropes (p=0.04); the difference was significant with cylindrical and mixed refractive errors but not with spherical refractive errors. Subjects in group-II revealed worse stereopsis as compared to group-I in all the three types of refractive errors (p<0.01). All subjects in group-III had absent stereo acuity.
Conclusion: Unequal refractive errors i.e. anisometropia with or without amblyopia could lead to subnormal stereopsis; this might be because of aniseikonia leading to disruption of binocular functions. Cylindrical and mixed refractive errors cause more difficulty in fusion of images as compared to spherical errors. It is important to identify subjects with anisometropia early so that amblyopia could be prevented and a better stereo acuity and fusion could be attained.
Key words: Refractive errors, Stereopsis, Amblyopia, Strabismus, Titmus fly stereogram, Anisometropia
