Vitamin intake and glaucoma risk: A systematic review and meta-analysis

Author: Han FF, Fu XX.

 

Geographical coverage: Not reported

Sector: Vitamins

Sub-sector: Glaucoma risk

Equity focus: Not reported

Study population: Patients with glaucoma

Review type: Epidemiology (association) review

Quantitative synthesis method: Meta-analysis

Qualitative synthesis method: Not applicable

Background

Glaucoma is a chronic disease that damages the optic nerve head (ONH) and the retinal nerve fibre layer (RNFL). Primary open-angle glaucoma, common among East Asians, is associated with older age, hyperopia, and high intraocular pressure (IOP). Research suggests that oxidative stress may impair the aqueous humour outflow system of the eye, thereby increasing IOP. Vitamins may reduce oxidative stress and influence the progression of glaucoma.

Objectives

To clarify the relationship between vitamin intake and the risk of glaucoma.

Main findings

Overall, the intake of high-dose vitamins A and B was associated with a lower prevalence of glaucoma, while the intake of vitamins C, D, and E showed no such association.

The authors identified 2,975 articles and included eight in the meta-analysis. The study populations exclusively consisted of individuals over the age of 40.

Seven studies reported a correlation between vitamin A intake and glaucoma. The meta-analysis demonstrated an association between vitamin A consumption and a reduced risk of glaucoma (odds ratio [OR] = 0.63, 95% confidence interval [CI]: 0.53 to 0.76, P < 0.001). Five studies examined the relationship between vitamin B intake and glaucoma. Similar to vitamin A, vitamin B intake was associated with a reduced risk of glaucoma (OR = 0.71, 95% CI: 0.64 to 0.80, P < 0.001). Another five studies examined the association between vitamin C and glaucoma, but the meta-analysis showed no significant relationship (OR = 0.69, 95% CI: 0.48 to 1.01, P = 0.05). One study indicated that high vitamin D intake might lower glaucoma risk; however, the meta-analysis found no clear evidence (OR = 0.90, 95% CI: 0.45 to 1.83, P = 0.78). Similarly, five studies evaluated vitamin E, but the meta-analysis found no definitive link to glaucoma (OR = 0.91, 95% CI: 0.71 to 1.16, P = 0.46).

Methodology

The authors searched PubMed, Embase, ScienceDirect, Cochrane Library, ClinicalTrials.gov, and Google Scholar for studies on nutrient intake and glaucoma. They included English-language studies published up to 18 September 2021 and scanned reference lists for additional relevant publications. All identified studies were screened against the eligibility criteria. Relevant data were extracted, and methodological quality was assessed using the Newcastle–Ottawa Scale. The findings were synthesised using meta-analysis. Effect sizes were expressed as odds ratios with 95% confidence intervals. Heterogeneity was assessed using I² statistics, and publication bias was evaluated using a funnel plot.

Applicability / External validity

The review authors did not specifically address applicability or external validity but noted that diverse populations were included, suggesting broad generalisability. However, a high risk of bias and reliance on self-reported data, along with the limited number of studies and small sample sizes, may limit the applicability of the findings to broader populations.

Geographic focus

The geographic location of the included studies was not reported. However, the authors stated that the studies involved populations of different races, including Asian, Caucasian, African, and Japanese groups.

Summary of quality assessment

Overall, there is low confidence in the conclusions of this study. While the review authors conducted a thorough database search for relevant studies, they did not search the reference lists of included studies and limited inclusion to English-language publications. Furthermore, they did not report the methods used to screen studies for inclusion or extract data from the included studies.

Publication Source:

Han FF, Fu XX. Vitamin intake and glaucoma risk: A systematic review and meta-analysis. J Fr Ophtalmol. 2022 May;45(5):519-528. doi: 10.1016/j.jfo.2021.10.010. Epub 2022 Feb 1. PMID: 35120728.
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