Plasma homocysteine levels, methylene tetrahydrofolate reductase A1298C gene polymorphism and risk of retinal vein thrombosis

Prevalence of homocysteinemia and effect of vitamin supplementation in retinal vein occlusion

Objective

The objective of this study was to determine the prevalence of homocysteinemia in patients with retinal vein occlusion (RVO). We investigated the association of B complex vitamin (BCV) and multivitamin (MVI) supplementation on homocysteine levels in RVO patients.

Methods and analysis

This cross-sectional study occurred at the Retina Center of New Jersey. We investigated 312 patients diagnosed with RVO between 2011 and 2019. Homocysteine levels were measured on diagnosis of RVO and 4–8 weeks after, following recommended daily supplementation with BCV, MVI or combination MVI+BCV.

Results

The median patient age was 71.00, IQR (61.00, 78.25), with 164 (52.6%) being women. Prevalence of homocysteinemia (>13 µmol/L) was 150 of 312 (48.1%), with a median baseline homocysteine level of 12.80 (10.17, 15.90) µmol/L. The follow-up cohort, 105 patients, demonstrated significant reduction in median homocysteine levels from 14.50 (12.30, 17.90) to 10.70 (9.30, 13.50) µmol/L following vitamin supplementation. Multivariate analysis found having baseline homocysteinemia was significantly associated with at least 25% reduction in homocysteine following vitamin supplementation.

Conclusions

In this study, 48.1% of patients with RVO had elevated homocysteine (>13 µmol/L). Supplementation with BCV or MVI+BCV was associated with a significant reduction in homocysteine from 14.50 (12.30, 17.90) to 10.70 (9.30, 13.50) µmol/L.

An Unusual Case of Concurrent Central Retinal Vein and Cilioretinal Artery Occlusion in a Healthy Patient

It is rare for young, healthy patients to have retinal venous or arterial occlusions and even rarer for both to occur in concert. Such an occurrence should prompt a rapid and extensive workup to prevent further complications. We present our patient, a 37-year-old Lebanese male, who reported a 3-day history of blurring of vision in his left eye. He had no medical or ocular history and is a nonsmoker. Examination of the left fundus revealed inferior macular edema and retinal whitening associated with tortuous retinal veins. He was diagnosed with a combined central retinal vein and cilioretinal artery occlusion. Emergency treatment was done for an acute arterial occlusion. Embolic and thrombotic causes were excluded with investigations. The only positive result was homozygosity for 677C>T mutation of the 5,10 methylenetetrahydrofolate reductase (MTHFR) enzyme gene. MTHFR enzyme breaks down homocysteine, which is atherogenic and prothrombotic. This mutation can lead to a prothrombotic state, precipitating this occurrence. In fact, the Lebanese population is known to have the highest incidence of such mutations, but there are surprisingly few reports on retinal vascular occlusions attributed to this. He was promptly treated with antiplatelet therapy, possibly preventing a full-blown central retinal vein occlusion. After 4 weeks, his vision improved to 6/6 bilaterally. Examination showed less tortuous veins, no more retinal whitening, resolution of macula edema and visual field defect. Hyperhomocysteinemia can be significant in patients without ischemic risk factors. It is vital to manage these patients promptly, preventing future sight and life-threatening events.

Methylenetetrahydrofolate reductase polymorphisms as risk factors for retinal venous occlusive disease: A literature review

The role of polymorphisms of methylenetetrahydrofolate reductase (MTHFR) gene in retinal vein occlusion (RVO) is a theme of discussion since the first reports of RVO in patients with MTHFR C677T mutation and without classic acquired risk factors for retinal vascular disease. The association between MTHFR polymorphisms and RVO has been studied over the last 20 years producing conflicting results. This review aims to summarize the literature concerning the role MTHFR polymorphisms as risk factors for RVO.