DEPRIVATION AND STRABISMIC AMBLYOPIA: ABNORMALITIES IN GENICULOCORTICAL VISUAL PATHWAYS

Abstract

Background: There are inconsistent data on the changes of functional performance in subcortical structures of visual system caused by early binocular vision impairment. Aim: To study neuronal functional activity of the dorsal lateral geniculate nucleus (LGNd) in monocularly deprived cats and strabismic cats. Materials and methods: 4 cats with monocular convergent strabismus, 7 cats with monocular divergent strabismus, 3 monocularly deprived cats and 4 intact cats were studied. Histochemical method was used to detect cytochrome oxidase – the mitochondrial enzyme of respiratory chain correlating with neuronal functional activity. Optical density in ocular-specific layers A and A1 was measured on the images of stained LGNd sections, and the contrast was calculated. Results: Relative reduction of functional activity in the layers innervated from deprived and squinted eyes was demonstrated in LGNd bilaterally. In strabismic animals, the changes were observed only in the projection of the central part of the visual field, whereas in monocularly deprived animals the changes were in the projection of the whole visual field. Conclusion: These findings indicate differences between the mechanisms determining the development of strabismic and deprivation amblyopia. Thus, in amblyopia, preservation of peripheral stereoscopic vision is possible.

Keywords

• strabismus
• monocular deprivation
• lateral geniculate body
• cytochrome oxidase