ICAM1 and diabetic retinopathy: It was reported that Opsin deletion in mice, which genetically mimics photoreceptor degeneration, prevents the diabetes-induced production of proinflammatory enzymes (such as iNOS and intercellular adhesion molecule 1 (ICAM-1) in the retina) [332], suggesting that inflammation originating from photoreceptors is of great importance in the pathogenesis of diabetic retinopathy.