Abstract
Abstract: :
Purpose: Elevated plasma total homocysteine (tHcy), low serum folate and vitamin B12 levels, and homozygosity for the thermolabile MTHFR genotype (TT) may be risk factors for retinal vascular occlusive disease. A meta-analysis of published reports was undertaken to further assess the role of these parameters in the etiology of this disease. Methods: A Medline search was performed to identify all published case control studies of tHcy, serum folate and vitamin B12 levels, and TT genotype in persons with retinal vascular occlusive disease. Main outcome measures included calculation of plasma tHcy, serum folate, and serum vitamin B12 standard differences, and odds ratios of TT genotype, between cases and controls. Results: In total, 614 patients with all types of retinal vein occlusion had higher tHcy levels than 762 controls (standard difference 0.867 (95% CI 0.735-0.999), p<0.001). Plasma tHcy levels were also higher in 154 patients with retinal artery occlusion compared with 358 controls (standard difference 1.174 (95% CI 0.947-1.402), p<0.001). Serum folates, but not vitamin B12 levels, were lower in 287 cases of retinal vascular occlusion than in the same number of controls (standard difference 0.508 (95% CI 0.340-0.675), p<0.001 and –0.060 (95% CI -0.024-0.104) p=0.474 respectively). Similar proportions of 690 patients with retinal vein occlusion and 2754 controls demonstrated the TT genotype, (odds ratio 1.332 (95% CI 0.995-1.783) p = 0.054) as did 152 patients with retinal artery occlusions, and 435 controls (odds ratio 1.716 (95% CI 0.977-3.014) p=0.060). Conclusions: Retinal vascular occlusion is associated with elevated plasma tHcy levels and low serum folate levels, but not serum vitamin B12 levels and TT genotype. Until a prospective multi-center trial is undertaken, plasma tHcy levels, serum folate and vitamin B12 levels should be determined in patients with retinal vascular occlusions and dietary supplementation with low doses of folate and vitamin B12 should be considered for affected persons.
Keywords: vascular occlusion/vascular occlusive disease • clinical (human) or epidemiologic studies: ris • clinical (human) or epidemiologic studies: tre