Findings from a recent study published in Investigative Ophthalmology & Visual Science evaluated the association between hormonal therapy (HT) use and the onset of glaucoma diagnosis in postmenopausal women.
Give me some background.
A previous study by the same Emory University-based group found an association between the age at diagnosis of menopause and glaucoma—regardless of the age a woman became postmenopausal.
- Findings: There was a 0.67-year-later diagnosis of glaucoma with each additional premenopausal year for women who developed glaucoma.
Tell me more.
Of note, postmenopausal women, regardless of age, have a 1.5-3 mmHg higher intraocular pressure (IOP) compared to age-matched premenopausal women.
Further, prior studies have demonstrated that postmenopausal women taking estrogen HT had a lower IOP (by 0.5-3 mmHg) compared to postmenopausal women not taking HT.
Talk about the study.
In this retrospective case-only study, investigators included female veterans with open-angle glaucoma (OAG) from the United States (U.S.) Department of Veterans Affairs (VA) records between 2000 and 2019.
Propensity score matching was used to match HT users (1,926) to untreated women (1,026) on variables including:
- Age of menopause
- Body mass index (BMI)
- Blood pressure
- Antihypertensive medications
- Comorbidity index
In addition, a simple linear regression was used to measure the impact of HT duration on the age of glaucoma diagnosis, and multivariate linear regression analysis was used to determine which factors contributed to the age at diagnosis of glaucoma.
Findings?
Researchers found a linear relationship between the age at diagnosis of glaucoma and menopause in women with HT (r = 0.54) and without HT (r = 0.57) use.
- Note: The Pearson correlation coefficient (r) can take on values between -1 and 1; the further away r is from 0, the stronger the linear relationship between two variables is.
Multivariate analyses revealed that certain durations of HT use were linked with later glaucoma diagnosis:
- 0-2 years of HT use
- Diagnosed 2.20 years later (95% confidence interval [CI] 1.64-2.76 years)
- 2-5 years of HT use
- Diagnosed 3.74 years later (95% CI 3.02-4.46 years)
- > 5 years of HT use
- Diagnosed 4.51 years later (95% CI 3.84-5.18 years)
Anything else?
A negative interaction (-0.009, 95% CI -0.015 to -0.003) was observed between HT duration and age of menopause diagnosis, with the impact of HT decreasing for later menopause ages.
- Meaning: The effect of HT on the age of glaucoma diagnosis decreases with the later age at menopause diagnosis
Predictors for the age at glaucoma diagnosis included:
- Age of menopause
- HT use
- White descent
- Use of antihypertensive medication
Any racial differences?
While the main predictive parameters (see above) for the age of glaucoma diagnosis were consistent across racial backgrounds, they observed a trend that suggested HT use was associated with a further delay in the age of glaucoma diagnosis in Black or African American patients compared to white patients.
- Note: This finding was not statistically significant in this study.
Expert opinion?
According to the study authors, “The observed later diagnosis of glaucoma with longer HT durations and the modulating effect of age of menopause suggests that estrogen supplementation may directly influence the pathophysiological processes involved in glaucoma development and progression.”
Limitations?
These included:
- The study did not differentiate between types of HT formulation or routes of administration.
- Previous research has shown that the type of HT formulation may impact the ability to prevent developing glaucoma.
- The analyses focused on veteran females only, and there was no IOP data on these patients.
- Analyzing estrogen-only HT in a specific patient population (i.e., women without a uterus) could have added bias.
- Evaluating HT containing estrogen and progesterone for additional analyses would be beneficial.
Take home.
These findings suggest that a longer duration of HT use was associated with a later diagnosis of glaucoma in postmenopausal women.
While further studies are required to validate these results, estrogen may play a protective role in glaucoma pathogenesis.