Effect of Coffee Consumption on Intraocular Pressure

Caffeine, a methylxanthine alkaloid, is a ubiquitous in-gredient in several popular beverages consumed world-wide (Figure 1) such as coffee, tea, and cola-flavored drinks. Caffeine increases the basal metabolic rate and acts as a central nervous system stimulant, myocardial stimulant, and smooth-muscle relaxant.1 It is often used in the treat-ment of migraine headache. The effect of caffeine on in-traocular pressure (IOP) is controversial.2-8 Many clinicians instruct patients with glaucoma to avoid coffee intake. The aim of the present study was to measure the effect of cof-fee ingestion on IOP in patients with normotensive glauco-ma or ocular hypertension. Methods The study sample included 6 patients with normotensive glaucoma and 22 patients with ocular hypertension (with no antiglaucoma medica-tion) attending the outpatients eye clinic of Rabin Medical Center. Pa-tients with a known allergy to caffeine, systemic hypertension or cardiac arrhythmia, psychological dependence (habituation = intake <10 g/d of regular coffee) on caffeinated beverages, and previous ocular surgery of any type were excluded. No patients took any medication prior to entry into the study and throughout the study. Additional caffeine intake was not allowed throughout the study. All patients verbally consented to par-ticipate in the study before entry. A crossover study design was used. Patients were randomized by computer-generated numbers (CGN program, Bargad Computers Co., Petah Tiqva, Israel) to receive regular or decaffeinated coffee (Elite Ltd., POB 82, Ramat-Gan, Israel). Seven to 10 days later, the patients re-turned for a second visit, and the beverage was switched. The regular and decaffeinated coffee were prepared in the same manner. The tota