Clinical and morphological characteristics of chorioretinal degeneration in early aging OXYS rats.

OXYS rats are characterized by early development of cataract and chorioretinal degeneration with clinical manifestations similar to those observed in senile cataract and age-associated macular degeneration in humans. According to fundoscopy findings, the incidence of chorioretinal degeneration sharply increases in OXYS rats by the age of 4.5 months, when all animals develop signs of fundus oculi pathology. Morphological analysis of semithin sections of the posterior wall of the eye in OXYS rats aged 5 months showed that choroid vessels, pigmented epithelium, and radial glia were most vulnerable to injury. Retinal hypoxia and destruction of the pigmented epithelium associated with circulatory disorders in the choroid vessels presumably lead to injuries of the neurosensory cells (mainly the external segments) and a 3.5-fold increase in the percent of photoreceptors with nuclear pyknosis in comparison with the control. These results indicate that OXYS rats represent an adequate model of age-associated macular degeneration and can be used for studies of the pathogenesis of this condition and development of methods for its treatment and prevention.