Role of hyperhomocysteinemia and Vitamin B12 deficiency in central and hemi-central retinal vein occlusion
Authors: Arthur Dhipak , John Deepa , Fleming Jude Joseph , Rebekah Grace , Gowri Mahasampath , John Sheeja Susan 
Published: May 2024

BACKGROUND:
Retinal venous occlusive diseases have been recognized as a major cause of ocular morbidity. Hyperhomocysteinemia could be a potentially modifiable risk factor.

OBJECTIVE:
To determine the association of hyperhomocysteinemia with central and hemi-central retinal vein occlusion (CRVO and HCRVO), the correlation of serum levels of homocysteine with Vitamin B12 and folate levels and the association of Vitamin B12 deficiency with hyperhomocysteinemia.

METHODS:
In this case–control study, patients with CRVO and HCRVO, and age- and gender-matched controls without CRVO and HCRVO, who met the eligibility criteria, were enrolled after obtaining informed consent. Data obtained from participants using a questionnaire, complete ophthalmological examination and relevant investigations, including estimation of serum homocysteine, Vitamin B12 and folate levels, were collated and analyzed.

RESULTS:
Thirty-nine cases with CRVO and HCRVO and 39 age- and gender-matched controls were studied. We found a significant association of hypertension (P < 0.01), hyperlipidemia (P = 0.01), and abnormal blood profile (P < 0.01) with retinal vein occlusion. There was no statistically significant association of hyperhomocysteinemia with CRVO and HCRVO (P = 0.81). However, we found a high prevalence of both hyperhomocysteinemia (43.58% of cases and 53.84% of controls; P = 0.81) and Vitamin B12 deficiency (23.08% of cases and 38.46% of controls; P = 0.14) in cases and controls, without a statistically significant difference between the two groups with respect to both parameters. Our study also found a negative correlation of serum levels of homocysteine with Vitamin B12 (Pearson correlation co-efficient − 0.3874, P = 0.0005), and folate (Pearson correlation coefficient − 0.3886, P = 0.0004) of the study participants. Among the study participants (n = 78), the odds of patients with Vitamin B12 deficiency having hyperhomocysteinemia were 7.0 (2.26–21.72) times those of patients without Vitamin B12 deficiency (P = 0.001). Similarly, among the cases (CRVO, n = 39), the odds of patients with Vitamin B12 deficiency having hyperhomocysteinemia were 7.0 (1.22–40.09) times those of patients without Vitamin B12 deficiency (P = 0.029). In the control group also (non-CRVO, n = 39), the odds of patients with Vitamin B12 deficiency having hyperhomocysteinemia were 6.67 (1.47–30.21) times those of patients without Vitamin B12 deficiency (P = 0.014).

CONCLUSION:
Hyperhomocysteinemia was not found to be an independent risk factor for retinal vein occlusion in our study. However, we found a high prevalence of hyperhomocysteinemia and Vitamin B12 deficiency in both cases and controls, without a statistically significant difference between the two groups with respect to both parameters. We also found a negative correlation of serum homocysteine levels with Vitamin B12 and folate levels. The odds of patients with Vitamin B12 deficiency having hyperhomocysteinemia were seven times those of patients without Vitamin B12 deficiency. Hypertension, hyperlipidemia, and abnormal blood profile had a significant association with CRVO and HCRVO. Many of the systemic risk factors for retinal vein occlusions are found to be associated with elevation of serum homocysteine levels, which may be part of a final common pathway in bringing about a state of accelerated atherosclerosis, leading to CRVO or HCRVO. Therefore, lowering serum levels of homocysteine by Vitamin B12 and folate supplementation could have a role in the prevention of these diseases.