Glaucoma and Coffee Consumption may be interrelated, Study says

Many studies of healthy persons, glaucoma suspects, or glaucoma patients have examined the acute effects on IOP of consuming various caffeine-containing substances. Most studies observed modest acute IOP increases after ingestion over a 1- to 4-hour period, ranging from 0 to 4 mmHg. Fewer studies have examined the relationship between habitual coffee consumption and IOP or glaucoma risk.

Therefore, Jihye Kim and colleagues from the Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts conducted this study to examine the association of habitual caffeine intake with intraocular pressure (IOP) and glaucoma and whether genetic predisposition to higher IOP modified these associations. The authors also assessed whether genetic predisposition to higher coffee consumption was related to IOP.

A total of 121 374 participants (baseline ages, 39–73 years) with data on coffee and tea intake (collected 2006–2010) and corneal-compensated IOP measurements were included in the study. In a subset of 77 906 participants with up to 5 web-based 24-hour-recall food frequency questionnaires (2009–2012), evaluated total caffeine intake and also assessed the same relationships with glaucoma (9286 cases and 189 763 controls).

The following findings were noted-

1. Mendelian randomization analysis did not support a causal effect of coffee drinking on IOP (P > 0.1).
2. Greater caffeine intake was associated weakly with lower IOP: the highest (≥232 mg/day) versus lowest (<87 mg/day) caffeine consumption was associated with a 0.10-mmHg lower IOP (P_trend = 0.01).
3. However, the IOP PRS modified this association: among those in the highest IOP PRS quartile, consuming > 480 mg/day versus < 80 mg/day was associated with a 0.35-mmHg higher IOP (P_interaction = 0.01).
4. The relationship between caffeine intake and glaucoma were null (P ≥ 0.1).
5. However, the IOP PRS also modified this relationship: compared with those in the lowest IOP PRS quartile consuming no caffeine, those in the highest IOP PRS quartile consuming ≥ 321 mg/day showed a 3.90-fold higher glaucoma prevalence.

Therefore, it was concluded that "habitual caffeine consumption was associated weakly with lower IOP and the association between caffeine consumption and glaucoma was null. However, among participants with the strongest genetic predisposition to elevated IOP, greater caffeine consumption was associated with higher IOP and higher glaucoma prevalence."