Bae et al. evaluated the effects of coffee, tea, and soft drinks on open-angle glaucoma (OAG) prevalence using the Korea National Health and Nutrition Examination Survey (KNHANES) from 2010-2011. The KNHANES is a population-based survey to represent the health-related status of South Koreans. Exclusion criteria for this analysis included age less than 19 years, pseudo- or aphakia, and retinal and neurological disease which may affect visual field test results. Participants were asked about beverage consumption - specifically coffee, tea, and soft drinks - during the previous 12 months. OAG was defined according to the International Society of Geographical and Epidemiological Ophthalmology (ISGEO) criteria. Visual-field testing was performed using frequency doubling technology (FDT). Beverage consumption over the past 12 months was assessed by questionnaire. There were 6,681 subjects who met the inclusion/exclusion criteria. The authors found that coffee consumption was significantly associated with OAG with an odds ratio of 2.06 (95% CI, 1.11-3.82). There was no association of tea or soft drink consumption with OAG. After stratification by gender, the correlation of OAG with coffee was significant in men (OR, 3.32; 95% CI, 1.53-7.20) but not in women (OR, 1.48; 95% CI, 0.61-3.54). The authors did not find a significant association of any beverage consumption with intraocular pressure.
The unique findings of the study relate to the association of coffee consumption with glaucoma in men but not in women. However, the reason for the different gender results is not clear. Additionally, as acknowledged by the authors, there are limitations to population studies including the inability to discern the detailed caffeine content ingested. Of course, such association studies do not prove causality so further studies would be helpful to discern the potential mechanisms by which coffee drinking can be linked to glaucoma development. In the final analysis, this study may be helpful to guide the Korean public in understanding yet another risk factor (coffee consumption) to perhaps avoid for those at risk for glaucoma, in particular, in men.