The medical literature has recognized that sickle cell trait is associated with severe and occasionally lethal systemic vascular occlusions under certain apparently predisposing circumstances. Ophthalmologists as well have come to suspect sickle cell trait as a participant in the development of ocular vascular occlusions in the presence of certain local and generalized conditions. Glaucoma and systemic alterations such as generalized vascular, hematologic, and metabolic abnormalities as well as systemic glaucoma therapy (osmotic agents and carbonic anhydrase inhibitors whose overall effect on sickling is unclear) have been incriminated. The article by Nagpal et al (p 325) supports this growing clinical suspicion that systemic factors altering the integrity of the vasculature or the metabolic and osmotic environment of the RBC may, in the presence of sickle cell trait, produce otherwise unsuspected or less likely ocular vascular disease. Impaired vision and blindness through direct infarctions of the optic nerve, choroid, or retina may