Homocysteine in Ocular Arterial and Venous Occlusive Disease

Abstract

Objectives: To evaluate homocysteine and methylentetrahydrofolat reductase (MTHFR 677 C → T) mutations as risk factors in ocular arterial and venous occlusive disease. Materials and methods: Over a period of 3.5 years (1/1999–8/2002) 410 patients with ocular occlusive disease presented to our tertiary care center. Of these, 362 patients (195 male, 167 female) were screened for hyperhomocysteinemia and MTHFR 677 C → T mutation. Results: Among these 362 patients, venous occlusions (45%) were less frequent than arterial occlusions (55%). Age between these subgroups did not differ significantly (p = 0,109). The following subgroups were analyzed: central retinal vein occlusion (n: 93), retinal branch vein occlusion (n: 70), central retinal artery occlusion (n: 41), retinal arterial branch occlusion (n: 49), anterior ischemic optic neuropathy (n: 68), posterior ischemic optic neuropathy (PION, n: 11) and amaurosis fugax (n: 30). A moderate hyperhomocysteinemia (≥12 μ mol/l) and a higher percentage of heterocygote MTHFR 677 C → T mutations was observed in the subgroup with PION. However, this difference was not significant when compared to the other subgroups. The homocysteine level did not differ significantly between patients without a MTHFR 677 mutation and those with a heterocygote or homocygote MTHFR 677 C→T mutation (p = 0,188). Conclusion: An increase in homocysteine levels has been discussed as an independent risk factor for thrombotic events. Evaluation of the MTHFR 677 C → T mutation does not seem necessary as, in vivo, such a mutation is known to only increase the level of homocysteine in the absence of sufficient folic acid. In our population the average homocysteine level was only elevated in PION which points against the need to routinely evaluate this parameter. However, as hyperhomocysteinemia is easily amenable to therapy through substitution of vitamin B6, B12 and folic acid, we recommend its evaluation in the absence of cardiovascular thrombotic risk factors.

KEYWORDS:

• Hyperhomocysteinemia
• MTHFR 677 C→T mutations
• retinal vein occlusion
• retinal artery occlusion
• ischemic optic neuropathy
• amaurosis fugax