The influence of manifest strabismus and stereoscopic vision on non-verbal abilities of visually impaired children.

This research was conducted in order to examine the influence of manifest strabismus and stereoscopic vision on non-verbal abilities of visually impaired children aged between 7 and 15. The sample included 55 visually impaired children from the 1st to the 6th grade of elementary schools for visually impaired children in Belgrade. RANDOT stereotest and polaroid glasses were used for the examination of stereoscopic vision, while Cover test and Hirschberg's pupils reflex test were used for the evaluation of strabismus. In the area of non-verbal abilities was evaluated visual discrimination, visuomotor integration, constructive praxia, visual memory, strategy formation, non-verbal reasoning and the representational dimension of drawings. Subtests of ACADIA test of developmental abilities were used for the evaluation of non-verbal abilities (Atkinson et al., 1972). Statistically significant relations between strabismus and constructive praxia (p=0.009), visual memory (p=0.037), strategy formation (0.040) and the quality of drawings were determined by the results analysis. According to our findings, children with divergent strabismus achieve the best results. Children with stereoscopic vision generally achieve better results in all the examined areas of non-verbal abilities, and statistically significant relations were determined in the areas of visuomotor coordination (0.002), constructive praxia (0.026) and non-verbal reasoning (0.015), which are directly connected to visuospatial abilities. Children with convergent strabismus achieve significantly lower results in the areas of constructive praxia, visual memory, strategy formation and representational dimension of drawings, and children with the lack of stereoscopic vision--in the areas of visuomotor integration, constructive praxia and non-verbal reasoning.