Effect of coffee consumption on intraocular pressure.

Background: Many ophthalmologists instruct patients with glaucoma to avoid coffee, although data supporting this practice are insufficient.

Objective: To estimate the effect of drinking coffee on intraocular pressure (IOP).

Methods: In this crossover study, the effect of the consumption of regular (180 mg caffeine in 200 mL beverage) and decaffeinated coffee (3.6 mg caffeine in 200 mL beverage) was compared in patients with normotensive glaucoma (n = 6) or ocular hypertension (n = 22). IOP was monitored in both groups at 30, 60, and 90 minutes after coffee ingestion.

Results: In patients with normotensive glaucoma who drank regular coffee, the mean +/- SD changes in IOP at 30, 60, and 90 minutes were 0.9 +/- 0.5, 3.6 +/- 1.1, and 2.3 +/- 0.66 mm Hg, respectively; in those who drank decaffeinated coffee, they were 0.75 +/- 0.36, 0.70 +/- 0.4, and 0.4 +/- 0.6 mm Hg, respectively. The corresponding values in patients with ocular hypertension were as follows: after regular coffee, 1.1 +/- 0.7, 3.4 +/- 1.0, and 3.0 +/- 2.7 mm Hg; and after decaffeinated coffee, 0.6 +/- 0.4, 0.9 +/- 0.2, and 0.5 +/- 0.5 mm Hg. The difference in the change in IOP from baseline after ingestion of regular versus decaffeinated coffee was statistically significant in each group at 60 and 90 minutes. Subjects who drank regular coffee demonstrated a greater elevation in IOP; this elevation may be clinically significant.

Conclusions: Intake of caffeinated beverage (>/=180 mg caffeine) may not be recommended for patients with normotensive glaucoma or ocular hypertension.