Atypical (Three-Quadrant) Central Retinal Vein Occlusion: A Report of two cases and review of literature.

PURPOSE: To report two cases with atypical central retinal vein occlusion involving three out of four retinal quadrants. METHODS: Report of two cases. RESULTS: A 54-year-old female, with a known history of type 2 diabetes mellitus, hypertension, and dyslipidemia for the past 15 years, presented with sudden painless loss of vision in the left eye; upon clinical evaluation she was found to have atypical central retinal vein occlusion involving three quadrants sparing the superio temporal quadrant, and complicated by cystoid macular edema. A 51-year-old female, with a known history of type 2 diabetes mellitus for the past 20 years and dyslipidemia, presented with sudden painless decrease in vision in the left eye; upon clinical evaluation she was found to have atypical central retinal vein occlusion involving three quadrants sparring the inferio temporal quadrant and associated with cystoid macular edema, eventually leading to retinal ischemia and neovascularization. CONCLUSION: Both cases highlight the rare finding of central retinal vein occlusion involving three out of four retinal quadrants. Only a few cases in the literature reported this rare observation, with the most likely explanation being an abnormal variation of retinal vascular anatomy.