There is considerable evidence that drinking caffeinated beverages, including coffee, causes eye pressure to go up, with even just one cup of coffee.
This effect is highest in glaucoma patients and people at risk for glaucoma.
However, eye pressure goes up only a small amount, so it is probably not a significant risk for people who do not suffer from glaucoma.
But, for people at risk of exfoliation glaucoma (a type of open angle glaucoma where some flake-like deposits are seen on the lens of the eye), drinking caffeine is associated with an increased risk of exfoliation glaucoma.
For example, in one study, it was shown that three or more cups of caffeinated coffee was associated with an increased risk of developing exfoliation glaucoma. The effect was strongest in women with a family history of glaucoma.
It’s important to note that this study doesn’t show that coffee causes glaucoma, but does suggest that drinking three or more cups of caffeinated coffee might not be good for your eyes if you already have glaucoma.
Further research on the effect of caffeine intake and progression of glaucoma was conducted by scientists at the International Islamic University of Malaysia in 2015, which published its paper entitled ‘Coffee Intake & Progression of Glaucoma’.
The aim of the study was to determine the association between coffee intakes and progression of glaucoma.
How was the study conducted?
A cross sectional study was conducted on 91 primary glaucoma patients who were on topical antiglaucoma drugs who were questioned on coffee consumption habits in 2011-12.
They then made physical examination on the patients including intraocular pressure (IOP) measurement and fundus examination for severity and progression of glaucoma.
What were the results of the study?
63 patients - 69% - were coffee drinkers.
Of those 63 people - 68% of them drank caffeinated coffee daily.
42 out of those 63 coffee drinkers who consumed caffeine in their diet developed progression of their disease after 4.4 years follow up.
Daily coffee drinking increased the risk of progression 8.1 folds (95% CI 2.5, 26.9) based on multivariate analysis.
What was the conclusion of the study?
The scientists concluded that drinking coffee daily was probably associated with glaucoma progression in this small study and that perhaps glaucoma patient should minimize or avoid caffeine intake.
Effect of caffeine on the intraocular pressure in patients with primary open angle glaucoma. Chandra P, Gaur A, Varma S. Clin Ophthalmol 2011. 5:1623-9.
The relationship between caffeine and coffee consumption and exfoliation glaucoma or glaucoma suspect: a prospective study in two cohorts. Pasquale LR, Wiggs JL, Willett WC, Kang JH. Invest Ophthalmol Vis Sci 2012. 53(10):6427-33.
The effect of caffeine on intraocular pressure: a systemic review and meta-analysis. Li M, Wang M, Guo W, Wang J, Sun X. Graefes Arch Clin Exp Ophthalmol 2011. 249(3):435-42.
Effects of caffeinated coffee consumption on intraocular pressure, ocular perfusion pressure, and ocular pulse amplitude: a randomized controlled trial. Jiwani AZ, Rhee DJ, Brauner SC, et al. Eye 2012 26(8):1122-30.