Hyperhomocysteinemia and low plasma folate as risk factors for central retinal vein occlusion: a case–control study in a Chinese population

To determine whether hyperhomocysteinemia and low plasma folate are risk factors for central retinal vein occlusion (CRVO) in the Chinese population.

A matched case–control study was conducted between July 2004 and May 2005. The study cohort consisted of 64 individuals that had been diagnosed to have CRVO and 64 normal controls (matched for age, gender, hypertension, smoking and drinking habits). None of the cases or controls had a history of diabetes, glaucoma, medication or any other vascular events that might minimize the influence on plasma homocysteine levels. A cross-sectional analysis among the 64 cases was performed to compare the prevalence of hyperhomocysteinemia and low plasma folate among subjects with and without ischemia and subjects with age above 45 and below 45 years. Plasma homocysteine level was measured by means of high-performance liquid chromatography and plasma folate concentration by radioimmunoassay.

The CRVO patients had a significantly higher homocysteine level (13.83±1.71 μmol/l) than the normal controls (8.05±0.58 μmol/l; p=0.003). The plasma folate levels were significantly lower in CRVO patients than in controls (5.62±0.39 ng/dl vs 7.23±0.60 ng/dl; p=0.032). A 1 μmol/l increase of plasma homocysteine level was associated with an odds ratio of 1.368. Hyperhomocysteinemia was defined as a homocysteine level of >14.97 μmol/l and was seen in 11 patients in the ischemic group, significantly more often than in the non-ischemic group (5 patients; p=0.030).

The results suggest that hyperhomocysteinemia and low plasma folate are independent risk factors for CRVO and are associated with the development of CRVO in the Chinese population.