Ischemic Type of Central Vein Occlusion in a Patient With Bietti Crystalline Dystrophy: A Longitudinal Follow-Up of 12 Years.

Bietti crystalline dystrophy (BCD) is a rare chorioretinal dystrophy associated with mutations in the CYP4V2 gene, characterized by intraretinal crystalline deposits and progressive chorioretinal degeneration. Retinal vein occlusion (RVO) is exceedingly rare in BCD, with only one previously reported case of tributary RVO without a detailed clinical description. We hereby describe a 44-year-old man with genetically proven stage 2 BCD who developed right central RVO (CRVO) eight years following the initial diagnosis in 2013. Though he did not notice any new visual disturbance in the right eye, routine fundus examination revealed subtle peripheral microvascular abnormalities and intraretinal small hemorrhages 360 degrees in 2021, and fluorescein angiography demonstrated nearly 360-degree peripheric nonperfusion with scattered microaneurysms, consistent with the diagnosis of ischemic CRVO. Four years later, the patient developed peripheric retinal neovascularizations and a small preretinal hemorrhage in his right eye that was managed solely with scatter laser photocoagulation. Unlike a previously reported case with retinitis pigmentosa and CRVO, in which neovascular complications did not arise, most likely due to extensive peripheral chorioretinal atrophy related to low VEGF levels, our case exhibited less peripheral chorioretinal atrophy; therefore, peripheral ischemia led to the development of retinal neovascularizations. Patients with BCD may not perceive peripheral retinal alterations due to their already compromised central vision; therefore, regular clinical visits seem beneficial to detect potential fundus changes promptly, as demonstrated in the present case.