Hormonal replacement therapy in postmenopausal women ≥50 years is associated with the incidence of glaucoma: Evidence from 6576 females in Finland

PURPOSE: Hormonal replacement therapy (HRT) in postmenopausal women appears to affect glaucoma risk, but findings are inconsistent. We aimed to explore whether the use of postmenopausal HRT plays a role in glaucoma development in Finland. METHODS: The main outcome variable was glaucoma incidence measured by initiation of special reimbursement due to glaucoma. The population-based historic cohort consisted of female participants aged ≥50 years whose incident glaucoma was recorded between January 1st, 2015, and December 31st, 2017. The main exposure of interest was postmenopausal HRT with Anatomic Therapeutic Chemical codes G03C (oestrogens), G03D (progestogens), G03F (progestogens and oestrogens in combination). The HRT treatment was initiated during 2001-2010. Frequencies and odds ratios (ORs) with 95% confidence intervals (CIs) were analyzed with logistic regression models, unadjusted and adjusted for diabetes mellitus, hospital district, socioeconomic status and statin exposure. RESULTS: Our nested-case-control study involved 1096 cases and 5480 age-matched controls. After adjustment for confounding factors, use of any HRT was associated with an increased risk for the development of glaucoma. The risk was found in estrogen users (adjusted OR, 1.33 [95% CI, 1.17-1.52]), in progestogen users (adjusted OR, 1.25 [95% CI, 1.02-1.53]) and in combinatory estrogen-progesterone users (adjusted OR, 1.19 [95% CI, 1.01-1.39]). In the POAG subgroup, the risk remained in estrogens-only users (adjusted OR, 1.31 [95% CI, 1.10-1.56]). CONCLUSIONS: Our data suggests that use of any postmenopausal HRT may increase the glaucoma risk, but in POAG subgroup estrogen-only therapy remained significant. Further research is needed to confirm the associations.