Purpose: To report a 24-year-old man with bilateral central retinal vein occlusions who had preceding episodes of prolonged transient monocular visual loss during which ophthalmoscopic findings were not suggestive of vein occlusion.
Method: Case report.
Result: Extensive hematologic studies for causes of vein occlusion were unremarkable with the exception of increased plasma homocysteine in the patient and in his asymptomatic father.
Conclusions: Impending vein occlusion should be considered in the differential diagnosis of transient monocular visual loss regardless of ophthalmoscopic appearance, and hyperhomocystinemia should be considered as a possible cause of retinal vein occlusion.