Eye News: Does Drinking Coffee Increase Glaucoma Risk?
Does Drinking Coffee Increase Glaucoma Risk?
(American Glaucoma Society 22nd Annual Meeting: Abstracts 83 and 23. Presented March 3, 2012.)
An analysis of the health records of more than 75,000 women has found a positive association between heavy coffee drinking and the development of exfoliation glaucoma (EG) or EG suspect, according to data presented here at the American Glaucoma Society 22nd Annual Meeting.
Lead investigator Dr. Louis Pasquale explained that previous randomized trials have indicated that homocysteine levels, a risk factor for coronary disease, are increased after coffee consumption, and that patients with EG have elevated homocysteine in the aqueous humor and tears.
Dr. Pasquale and colleagues used data collected in the Nurses' Health Study from 1980 to 2008 for their study. To be included, subjects had to be at least 40 years of age, had to have no history of glaucoma or cancer, and had to have reported eye exams.
Patients were identified as having EG if there was evidence on a slit-lamp exam and 2 or more reliable visual fields showing reproducible loss. For patients with EG suspect, the presence of exfoliation material on the slit-lamp exam was required, as was an intraocular pressure (IOP) above 21 mm Hg or a cup-to-disc ratio of 0.6 or higher.
A validated questionnaire was used to assess total caffeine intake (from coffee, tea, soda, and caffeine-containing food) every 4 years. A multivariate analysis was performed to determine the association between caffeine consumption and the incidence of EG.
Results:
- The investigators found 300 cases of EG over 1.6 million person-years of follow-up.
- Women who consumed 500 mg caffeine or more per day (1 cup of coffee has roughly 150 mg of caffeine) had a nonsignificant but numerically increased risk for EG, compared with those who consumed less than 125 mg per day.
- People who drank 3 or more cups of coffee daily had a relative risk for EG of 1.63, compared with those who abstained from drinking coffee.
- The association between coffee intake and EG was stronger in people with a family history of glaucoma than in people with no family history.
- Given these data, which he cautions are preliminary, Dr. Pasquale does not think that routine checking of homocysteine levels or advising changes in coffee consumption are warranted until stronger associations are proven.
A second study reported at the American Glaucoma Society meeting was an investigation of the effect of modest caffeine intake — one 8 oz (237 mL) cup of coffee — on intraocular pressure.
This prospective investigation involved 106 subjects — 22 with high-tension primary open-angle glaucoma (POAG), 18 with normal-tension glaucoma, 20 with ocular hypertension, 21 with suspected glaucoma and 25 healthy control subjects.
Randomized subjects ingested 8 oz of either caffeinated (182 mg) or decaffeinated (4 mg) coffee at the first clinic visit; at the second clinic visit, they ingested the alternate beverage. Blood pressure,intraocular pressure, ocular perfusion amplitude, and heart rate were measured before and 60 and 90 minutes after coffee consumption.
At baseline, there were no differences in intraocular pressure a between treatment groups. Sixty minutes after caffeinated coffee intake, mean change in intraocular pressure was 0.99 mm Hg and in ocular perfusion pressure was 1.06 mm Hg. Ninety minutes after caffeinated coffee intake, mean change from baseline in intraocular pressure was 1.26 mm Hg and in ocular perfusion pressure was 0.23 mm Hg.
The investigators concluded that although caffeine did have an observable effect, these 1-time modest increases are unlikely to have a clinical impact on this population.
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