Use of postmenopausal hormones containing estrogen may reduce the risk for primary open-angle glaucoma, according to a report published online January 30 in JAMA Ophthalmology.
Several lines of evidence point to a role for estrogen in lowering intraocular pressure and, therefore, possibly the risk for glaucoma. Previous experiments using a rat model of retinal ischemia demonstrate a protective effect of oral estrogen. In addition, several studies that evaluated clinic populations, including the Nurses' Health Study, have shown an association between modestly reduced intraocular pressure and use of hormone preparations containing estrogen. The presence of estrogen receptors on ganglion cells of the retina suggests a mechanism for the effect.
In the current study, Paula Anne Newman-Casey, MD, assistant professor of ophthalmology and visual sciences at the University of Michigan Medical School and colleagues used a retrospective longitudinal cohort analysis of data from outpatient pharmacy records to investigate a possible association between postmenopausal hormone use and risk of developing primary open-angle glaucoma.
The researchers considered effects of estrogen, estrogen plus progesterone, or estrogen plus androgen on risk for glaucoma. Of 152,163 women aged 50 years or older in a managed care plan for at least 4 years who had visited an eye care provider at least twice between 2001 and 2009, 2925 (1.9%) developed glaucoma.
Results revealed a small effect for estrogen alone. For each month women took just estrogen, the relative risk for glaucoma fell by 0.4 (hazard ratio, 0.996; 95% confidence interval [CI], 0.993 - 0.999; P = .02). Use of estrogen plus progesterone preparations was not associated with change of risk as the number of months increased (HR, 0.994; 95% CI, 0.987 - 1.001; P = .08), nor was use of estrogen and androgen preparations (HR, 0.999; 95% CI, 0.988 - 1.011; P = .89).
Limitations of the investigation include reliance on pharmacy billing data rather than clinical data and restriction of the patient pool to those who have health insurance. The analysis also did not consider patient compliance.
The researchers conclude that postmenopausal hormone preparations that contain estrogen may decrease the risk of developing primary open-angle glaucoma. They call for further research into the association and mechanism of an effect of estrogen on intraocular pressure, especially in light of the 2005 US Preventive Services Task Force recommendations to limit postmenopausal hormone use because of increased risks for breast cancer, cardiovascular disease, and dementia.
Funding came from the National Eye Institute, American Glaucoma Society, Blue Cross Blue Shield of Michigan Foundation, Research to Prevent Blindness, Heed Foundation Fellowship, the Harvard Glaucoma Center of Excellence, the Margolis Fund, and the Arthur Ashley Foundation. The authors have disclosed no relevant financial relationships.
JAMA Ophthalmol. Published online January 30, 2014. Abstract
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