Plasma homocysteine in patients with retinal vein occlusion

Purpose: To evaluate total plasma homocysteine (HCY) during fasting and post methionine load test (MLT), serum folate, serum vitamin B-12, and methylenetetrahydrofolate reductase (MTHFR) mutation in patients with retinal vein occlusion (RVO) and to examine the association between these risk factors and 2 subtypes of RVO: central (CRVO) and branch (BRVO). Methods: This case-control study included 91 Italian patients presenting a first RVO and 71 healthy subjects, matched by age, without history of thromboembolic diseases, glaucoma, or malignancy. Homocysteine fasting and after MLT, serum folate level, serum vitamin B-12 level, and other laboratory tests were assessed. Genetic analysis for the C677T MTHFR mutation was performed. Results: Multivariate logistic regression analysis indicated that hypertension (odds ratio [OR] 2.63; 95% confidence interval [Cl] 1.30-5.30; p = 0.007), higher values of fasting HCY (OR 1.16; 95% Cl 1.01-1.33; p = 0.03), and low concentrations of vitamin B-12 (OR 0.99; 95% Cl 0.995-0.999; p = 0.01) were independently correlated with RVO. Moreover, the main determinants for CRVO risk were hypertension (OR 2.46; 95% CL 1.06-5.72; p = 0.04), high values of fasting HCY (OR 1.20; 95% Cl 1.02-1.41; p = 0.03), and low concentrations of vitamin B-12 (OR 0,99; 95% Cl 0.994-0.999; p = 0.008), whereas for BRVO risk only hypertension was significant (OR 2.74; 95% Cl 1.24-6.03; p = 0.01). Genotype distribution of the MTHFR C677T mutation did not reveal any significant difference between patients and controls. Conclusions: These results suggest that elevated fasting HCY levels, low vitamin B-12 levels, and hypertension are associated with a risk of RVO, especially for CRVO. Moreover, our data suggest that only hypertension is associated with BRVO risk.