Interaction between micronutrients; vitamin a, zinc and iron in the eye (biochemical and histological studies)

Abstract

The association of visual impairment and poor diet has long been recognized. The retina and retinal pigment epithelium have the highest trace mineral content as compared to any body tissue. Malnutrition as a cause of blindness has been under estimated. This study aimed to investigate the relation between both deficiency as well as the excess of micronutrients (Vitamin A, zinc and iron) and the ocular eye diseases. This work was done on 48 albino rats divided into six groups. Group one fed on control basal diet, group two, three and four were fed on a diet free from vitamin A, iron, and zinc respectively. Group five was fed on a diet free from all the above micronutrients while group six was fed on a diet contain excess of all these micronutrients. At the end of the feeding period, ophthalmological and histological examinations were done to all rats. The level of vitamin A was estimated in the serum and the concentration of zinc and iron were determined in the cornea, lens and retina. Also total protein and its fractions were estimated in the lens. The result of this study showed that cortical cataract was detected in the rats fed on the diet containing deficient or excess micronutrients. The level of vitamin A in serum and the concentration of iron and zinc in cornea, lens and retina revealed a significant change in different tissues studied due to different treatment especially in deficient and excess groups. Histological examination revealed photoreceptor degeneration in the retina and intact endothelial cells of the cornea. The data of this work also revealed that the level of these micronutrients in the diet affect ocular function, therefore they have to be provided in adequate amounts that satisfy the physiological requirements to avoid eye complications.