Cephaloridine-induced retinopathy by intravitreal injection: an ultrastructural study

We evaluated retinal toxicity produced by intravitreal injection of 25 mg cephaloridine, noting the progression of destruction over a 4 week period. Clinically, intravitreal injection of cephaloridine caused thrombosis of intravitreal vessels in the vascularized portion of the rabbit retina within 2 days. Ultrastructurally, 12 hours after injection there were membrane and cystoplasmic disturbances in the pigment epithelium. Degenerative changes in the outer and inner segments were first observed 48 hours after injection and continued until 120 hours. Phagocytic cells of pigment epithelial cell derivation responded to photoreceptor degeneration by phagocytosis of degenerated outer and inner segments. After 120 hours all outer segments were completely destroyed and all surviving inner segments appeared to be normal. Evidence for the regeneration of outer segments by remaining photoreceptor elements was not found. Hence, the irreversible nature of damage due to intravitreal injection of a toxic dose of an antibiotic is noted.