Coffee Tied to Glaucoma Risk in United States

Larry Hand

October 08, 2012

October 8, 2012 — Heavy consumption of caffeinated coffee is associated with an increased risk for exfoliation glaucoma (EG) or exfoliation glaucoma suspect (EGS), especially in women with a family history of glaucoma, according to a study published in the October issue of Investigative Ophthalmology and Visual Science.

Louis R. Pasquale, MD, from the Massachusetts Eye and Ear Infirmary and Harvard Medical School in Boston, and colleagues analyzed data from 2 large cohort studies, the Nurses' Health Study (NHS; n = 78,977 women) and the Health Professionals Follow-Up Study (HPFS; n = 41,202 men). In the current analysis, the researchers included cohort members who were at least 40 years old, did not have glaucoma at baseline (1980 for NHS and 1986 for HPFS), and had been followed up through 2008, the last year of the NHS. The researchers confirmed 360 EG/EGS cases for this analysis by reviewing medical records and validating diagnoses through eye care providers.

The researchers found that caffeinated coffee significantly increased the risk for EG/EGS (P trend = .02). People who drank 3 or more cups per day had a 1.66-fold higher risk for EG/EGS (95% confidence interval [CI], 1.09 - 2.54) compared with people who drank no coffee. In contrast, there was no significant association between total caffeine intake from all beverages and incidence of EG/EGS (P trend = .06), nor were there associations between other caffeinated drinks and EG/EGS (P trend > 0.31).

When the researchers used US Department of Agriculture data to convert coffee consumption to milligrams caffeine per day, they found that people who drank 500 mg/day or more of overall caffeine had a 1.43-fold greater multivariate relative risk (MVRR) for EG/EGS (95% CI, 0.98 - 2.08) compared with people who drank less than 125 mg/day of overall caffeine.

Women in the higher consumption group with a family history of glaucoma had a 2.94 MVRR for EG/EGS (95% CI, 1.16 - 7.46) compared with a 1.16 MVRR for women in that group with no family history of glaucoma (95% CI, 0.72 - 1.88).

"Because this is the first study to evaluate the association between caffeinated coffee and exfoliation glaucoma in a U.S. population, confirmation of these results in other populations would be needed to lend more credence to the possibility that caffeinated coffee might be a modifiable risk factor for glaucoma," senior author Jae Hee Kang, ScD, from Brigham and Women's Hospital in Boston, said in a news release. "It may also lead to research into other dietary or lifestyle factors as risk factors."

Previous research has shown that greater coffee consumption is linked to increased risk for glaucoma among Scandinavian populations.

Coffee's effect of elevating levels of homocysteine "represents a biologically plausible link between coffee and ES," the researchers write. Another factor may be the presence of chologenic acid, which is found in coffee but not in other caffeinated beverages, they write.

One limitation of their study is that because more than 90% of the study population was white, generalization to more diverse populations may not be possible. Strengths, however, include the fact that was that it was a large, prospective study with a long follow-up period, and that recall bias was highly unlikely.

The researchers conclude, "[W]e found that heavier caffeinated coffee consumption was associated with increased risk of EG/EGS. The effect modification by family history on the association with caffeine deserves further study."

This study was supported by the National Institutes of Health, the Arthur Ashley Foundation, and the Harvard Glaucoma Center of Excellence. The authors have disclosed no relevant financial relationships.

Invest Ophthalmol Vis Sci. 2012:53:6427-6433. Abstract