Plasma homocysteine concentrations in acute and convalescent changes of central retinal vein occlusion in a Chinese population.

Abstract

Homocysteine is a potential risk factor for central retinal vein occlusion (CRVO), but this remains controversial. We measured fasting total plasma homocysteine (tHcy) concentrations immediately after CRVO and in the convalescent period to investigate this controversy. We measured fasting tHcy concentrations in 36 consecutive patients with CRVO within three days; and at 1, 3, and 6 months after CRVO; and once in 36 control subjects. The vitamin B12 and folate levels, and the presence of C677T MTHFR polymorphisms, were analyzed in all patients and controls. Median tHcy concentrations were not significantly higher than in matched control subjects in the acute phase of CRVO (9.66 [10.75 ± 4.09] vs. 9.25 [9.96 ± 4.02] μmol/L, P = 0.371) and 1 month after CRVO (P = 0.119). However, tHcy levels increased significantly in the convalescent period and were significantly higher than in control subjects at 3 CRVO (P = 0.010) and 6 (P < 0.001) months after CRVO. Furthermore, tHcy levels of the ischemic CRVO patients at 6 months after CRVO were significantly higher than in nonischemic CRVO patients (P = 0.028). However, these observations did not appear to be explained by alteration in serum folate, vitamin B12 concentrations, and the MTHFR C677T genotype. The tHcy levels are not immediately elevated after CRVO, but increase in the convalescent period. These data do not support the hypothesis that raised tHcy concentrations are independent risk factor for CRVO. Instead, it is possible that elevated tHcy levels may be caused by the disease process itself.