Hyperhomocysteinemia and central retinal vein occlusion in Iranian population

Prevention and Treatment of Retinal Vein Occlusion: The Role of Diet-A Review

Retinal vein occlusion (RVO) is the second most common retinal disorder. In comparison to diabetic retinopathy or age-related macular degeneration, RVO is usually an unexpected event that carries a greater psychological impact. There is strong evidence to suggest that cardiovascular diseases are the most common risk factors in this pathology and it has long been known that a higher consumption of fish, nuts, fruits, and vegetables has a protective effect against these types of conditions. In the last several years, interest in plant-based diets has grown in both the general population and in the scientific community, to the point to which it has become one of the main dietary patterns adopted in Western countries. The aim of this review is to investigate the potential impact of macro- and micronutrients on retinal vein occlusion.

Homocysteine, methylenetetrahydrofolate reductase C677T polymorphism, and risk of retinal vein occlusion: an updated meta-analysis

Background

To evaluate the role of plasma total homocysteine (tHcy) and homozygosity for the thermolabile variant of the methylenetetrahydrofolate reductase (MTHFR) C677T genotype in the risk of retinal vein occlusion (RVO).

Methods

Relevant studies were selected through an extensive search of PubMed, EMBASE, and the Web of Science databases. Summary weighted mean differences (WMDs) or odds ratios (ORs) and 95% confidence intervals (CI) were calculated with a random-effects model.

Results

Forty-two studies with 6445 participants were included in this updated systematic review and meta-analysis. The mean plasma tHcy level in the RVO patients was significantly higher than in the controls (WMD =2.13 μmol/L; 95% CI: 1.29 to 2.98, P < 0.001), but there was evidence of between-study heterogeneity (P < 0.001). No significant association between MTHFR C677T genotype and RVO was found under all genetic models.

Conclusion

There was some evidence that plasma tHcy is associated with an increased risk of RVO. There was no evidence to suggest an association between homozygosity for the MTHFR C677T genotype and RVO.

Hyperhomocysteinia is a risk factor for retinal venous occlusion: a case control study

BACKGROUND

We evaluated the role of hyperhomocysteinemia as a risk factor for retinal vein occlusion (RVO) in Indian patients.

TYPE OF STUDY

Matched case control type of longitudinal study was conducted in 2006-2007.

MATERIALS AND METHODS

Two medical retina specialists examined the eyes having an event of RVO in the last 15 days. A similar number of eyes without RVO were also examined. The serum and urine homocysteine levels of these persons were tested. Matched pair analysis was carried out to determine the risk of RVO among those with hyperhomocysteinemia.

RESULTS

We included 20 cases of RVO and 20 age- and sex-matched persons without RVO. The risk of RVO was significantly higher in persons with hyperhomocysteinemia [difference of mean 31.62 μmol/L (95% Confidence Interval 16.60-47 . 86), P = 2.1 × 10-13 ]. The mean urine homocysteine level among cases and controls was not statistically significant. There were 12 persons with hypertension in both cases and control groups.

CONCLUSION

Hyperhomocysteinemia is a risk factor for RVO. Any list of investigations for a case of RVO should include total plasma homocysteine (tHcy) levels.

A longitudinal analysis of risk factors associated with central retinal vein occlusion

PURPOSE

To identify risk factors associated with central retinal vein occlusion (CRVO) among a diverse group of patients throughout the United States.

DESIGN

Longitudinal cohort study.

PARTICIPANTS

All beneficiaries aged ≥ 55 years who were continuously enrolled in a managed care network for at least 2 years and who had ≥ 2 visits to an eye care provider from 2001 to 2009.

METHODS

Insurance billing codes were used to identify individuals with a newly diagnosed CRVO. Multivariable Cox regression was performed to determine the factors associated with CRVO development.

MAIN OUTCOME MEASURES

Adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) of being diagnosed with CRVO.

RESULTS

Of the 494 165 enrollees who met the study inclusion criteria, 1302 (0.26%) were diagnosed with CRVO over 5.4 (± 1.8) years. After adjustment for known confounders, blacks had a 58% increased risk of CRVO compared with whites (HR, 1.58; 95% CI, 1.25-1.99), and women had a 25% decreased risk of CRVO compared with men (HR, 0.75; 95% CI, 0.66-0.85). A diagnosis of stroke increased the hazard of CRVO by 44% (HR, 1.44; 95% CI, 1.23-1.68), and hypercoagulable state was associated with a 145% increased CRVO risk (HR, 2.45; 95% CI, 1.40-4.28). Individuals with end-organ damage from hypertension (HTN) or diabetes mellitus (DM) had a 92% (HR, 1.92; 95% CI, 1.52-2.42) and 53% (HR, 1.53; 95% CI, 1.28-1.84) increased risk of CRVO, respectively, relative to those without these conditions.

CONCLUSIONS

This study confirms that HTN and vascular diseases are important risk factors for CRVO. We also identify black race as being associated with CRVO, which was not well appreciated previously. Furthermore, we show that compared with patients without DM, individuals with end-organ damage from DM have a heightened risk of CRVO, whereas those with uncomplicated DM are not at increased risk of CRVO. This finding may provide a potential explanation for the conflicting reports in the literature on the association between CRVO and DM. Information from analyses such as this can be used to create a risk calculator to identify possible individuals at greatest risk for CRVO.

Homocysteine, methylenetetrahydrofolate reductase C677T polymorphism, and risk of retinal vein occlusion: a meta-analysis

OBJECTIVE

To assess the role of plasma total homocysteine (tHcy) concentrations and homozygosity for the thermolabile variant of the methylenetetrahydrofolate reductase (MTHFR) C677T gene as risk factors for retinal vascular occlusive disease.

DESIGN

Retinal vein occlusion (RVO) is an important cause of vision loss. Early meta-analyses showed that tHcy was associated with an increased risk of RVO, but a significant number of new studies have been published.

PARTICIPANTS AND/OR CONTROLS

RVO patients and controls.

METHODS

Data sources included MEDLINE, Web of Science, and PubMed searches and searching reference lists of relevant articles and reviews. Reviewers searched the databases, selected the studies, and then extracted data. Results were pooled quantitatively using meta-analytic methods.

MAIN OUTCOME MEASURES

tHcy concentrations and MTHFR genotype.

RESULTS

There were 25 case-control studies for tHcy (1533 cases and 1708 controls) and 18 case-control studies for MTHFR (1082 cases and 4706 controls). The mean tHcy was on average 2.8 micromol/L (95% confidence interval [CI], 1.8-3.7) greater in the RVO cases compared with controls, but there was evidence of between-study heterogeneity (P<0.001, I(2) = 93%). There was funnel plot asymmetry suggesting publication bias. There was no evidence of association between homozygosity for the MTHFR C677T genotype and RVO (odds ratio [OR] 1.20; 95% CI, 0.84-1.71), but again marked heterogeneity (P = 0.004, I(2) = 53%) was observed.

CONCLUSIONS

There was some evidence that elevated tHcy was associated with RVO, but not homozygosity for the MTHFR C677T genotype. Both analyses should be interpreted cautiously because of marked heterogeneity between the study estimates and possible effect of publication bias on the tHcy findings.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.