Heavy Drinking and Smoking Linked to Higher Glaucoma Odds in Large African Study

Alcohol consumption and tobacco smoking are both associated with substantially higher odds of primary open-angle glaucoma among adults in sub-Saharan Africa, according to one of the largest studies of substance use and glaucoma ever conducted on the continent. The research, part of the Eyes of Africa: Genetics of Blindness study, analysed 9,418 people aged 40 and over across Nigeria, Ghana and Malawi between 2017 and 2023, including 5,189 individuals diagnosed with primary open-angle glaucoma and 4,229 controls without the disease.

Primary open-angle glaucoma is the most common form of glaucoma worldwide, accounting for roughly three-quarters of cases, and it is particularly burdensome in Africa. An estimated 8.7 million Africans aged 40 to 80 live with the condition, a figure projected to nearly double to 16.2 million by 2040. The disease is a chronic progressive optic neuropathy that damages the optic nerve and causes irreversible blindness, and while elevated intraocular pressure is its primary modifiable driver, glaucoma can also develop at pressures that appear normal, prompting researchers to look for other contributing factors.

In the new study, published in Eye and Vision, participants underwent comprehensive ocular examinations including Goldmann applanation tonometry, gonioscopy and stereoscopic optic nerve assessment, with glaucoma classified according to the International Society of Geographical and Epidemiological Ophthalmology criteria. Structured interviews collected detailed information on alcohol, tobacco, pharmaceutical and illicit substance use, distinguishing never, former and current users for each substance. Former drinkers, defined as those who had not consumed alcohol in the 30 days before interview, had 49 percent higher odds of glaucoma than never-drinkers after full statistical adjustment (odds ratio 1.49; 95 percent confidence interval 1.33 to 1.66), while current drinkers showed a smaller but still significant 15 percent increase in odds.

The pattern of drinking mattered as much as whether people drank at all. Among participants with any history of alcohol use, those who reported that the largest amount they had ever consumed in a single day exceeded two standard drinks faced 40 percent higher odds of glaucoma than lighter drinkers, a measure the investigators describe as lifetime heavy episodic drinking. Drinking more than two drinks on a single occasion was reported by 31.2 percent of glaucoma cases compared with 24.4 percent of controls. By contrast, the average number of drinks consumed per month among current drinkers did not differ significantly between the groups, suggesting that episodic intensity, rather than routine frequency, may be the more important dimension of alcohol exposure in this relationship.

Tobacco smoking showed an independent association with the disease as well. Former smokers had 38 percent higher odds of glaucoma than people who had never smoked, and current smokers had 46 percent higher odds, with both results statistically significant after adjustment for alcohol use and other covariates. Notably, among the 896 participants with a smoking history, neither how recently they had smoked nor how many cigarettes they smoked per day differed meaningfully between cases and controls, with about three-quarters of smokers in both groups reporting five or fewer cigarettes daily. The authors interpret this as indicating that the population-level association was driven by exposure prevalence rather than a clear dose-response gradient, implying that any tobacco exposure may carry meaningful risk.

The study also confirmed well-established demographic patterns. Men had 40 percent higher odds of glaucoma than women, and odds rose steeply with age, reaching 83 percent higher among those aged 80 and over compared with adults in their forties and fifties. Higher educational attainment was associated with a 27 percent increase in odds and unemployment with a 23 percent increase, while people born outside Nigeria had 20 percent lower odds. The authors suggest the education finding likely reflects selection bias, since better-educated individuals may have greater access to hospital-based eye care and are therefore more likely to be diagnosed.

A crucial sensitivity analysis complicates the alcohol story. When the researchers restricted the sample to current and never users of both substances, excluding all former users, current smoking remained independently associated with glaucoma, with the association actually strengthening to an odds ratio of 1.62. Current alcohol consumption, however, was no longer significantly associated with the disease and was dropped from the final model. The authors suggest the alcohol findings of the primary analysis may reflect protopathic bias, in which people diagnosed with glaucoma or pressure-related symptoms reduce or stop drinking on medical advice, so that former drinkers represent those with the longest cumulative exposure before cessation. Prospective studies are needed to clarify the direction of the alcohol-glaucoma relationship in African populations.

Several other findings warrant careful interpretation. Marijuana use was slightly more prevalent among glaucoma cases in the crude analysis, at 1.8 percent versus 1.1 percent among controls, but this association did not persist in the multivariable model, and the authors note that reverse causation is possible if patients initiated cannabis use based on publicised claims that it lowers intraocular pressure. Reported use of tranquillisers and painkillers was associated with lower odds of glaucoma, but the researchers explicitly state this does not indicate a protective effect and may reflect confounding by indication, chance, or differential reporting bias between clinic-based cases and controls. Other illicit drugs were too rare in the population to analyse meaningfully.

The authors emphasise that the cross-sectional design precludes conclusions about causality or temporal order, and that self-reported substance use is vulnerable to recall and social-desirability bias. Cumulative exposure metrics such as pack-years and lifetime alcohol units were not captured, limiting dose-response analysis, and the control group was drawn largely from the same clinical settings as the cases, so selection bias cannot be excluded. Nearly 99 percent of glaucoma patients were enrolled from glaucoma clinics, while most controls came from cataract and general outpatient clinics. If the associations are confirmed in longitudinal research, the authors argue that substance use reduction could become a component of primary prevention strategies for glaucoma in Africa, where current public health campaigns focus primarily on regular eye examinations and family history.

The findings arrive amid inconsistent international evidence on tobacco and glaucoma. Two recent large systematic reviews and meta-analyses encompassing hundreds of thousands of participants found no statistically significant association between smoking and glaucoma incidence, whereas the present study, the largest comparative analysis of substance use and glaucoma in Africa to date, reports significant associations for both former and current smoking. The authors point to proposed biological mechanisms, including tobacco-induced vasoconstriction reducing ocular blood flow, oxidative damage to the trabecular meshwork and retinal ganglion cells, and alcohol-related elevations in intraocular pressure and disruption of vascular regulation, while stressing that these pathways remain to be tested prospectively in African populations.

Subject of Research: Associations between alcohol and tobacco use and primary open-angle glaucoma in sub-Saharan Africa

Article Title: Association between alcohol and tobacco use and primary open-angle glaucoma: the Eyes of Africa study

Article References: Hussain, O. J., Olawoye, O., Stuart, K. V., Sarimiye, T., Chuka-Okosa, C., Idakwo, U., Tagoe, N. N., Amissah-Arthur, K. N., Adenrele, K. O., Kizor-Akaraiwe, N., Okeke, C. A., Adedeji, A. O., Adekoya, B., Baiyeroju, A., Akpa, O. M., Majekodunmi, O., Uche, N., Adegbehingbe, B., Onakoya, A., … Ashaye, A. (2026). Association between alcohol and tobacco use and primary open-angle glaucoma: the Eyes of Africa study. Eye and Vision, 13(1), Article 44. https://doi.org/10.1186/s40662-026-00515-y

Image Credits: AI Generated

DOI: 10.1186/s40662-026-00515-y

Keywords: primary open-angle glaucoma, alcohol consumption, tobacco smoking, Eyes of Africa study, Nigeria, Ghana, Malawi, cross-sectional study, risk factors, intraocular pressure, optic neuropathy, sub-Saharan Africa