Glaucoma and Coffee Consumption may be interrelated, Study says

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."