Faculty members at the University of Colorado Anschutz School of Medicine are working together across academic departments to learn more about how menopausal hormone therapy, sometimes referred to as hormone replacement therapy, affects women’s bodies. Among their many focuses is eye health.
“We know that hormones affect the retina,” says Jenna Patnaik, PhD, associate professor of ophthalmology, who has a keen research interest in identifying sex differences in ophthalmic disease. “And we know that that age-related macular degeneration (AMD) is more common in females.”
This knowledge informs a solid foundation for investigating whether menopausal hormone therapy often used to relieve symptoms of perimenopause and menopause, has any impact on the development or progression of AMD, a leading cause of vision loss over the age of 50.
Researchers suspect having a longer lifespan, the likeliness of an autoimmune disorder, and hormonal changes, especially declining estrogen, may play a role in AMD in women, but more research is needed.
In AMD, damage to the macula, which is part of the retina, progressively diminishes central vision over time. It can happen slowly in some people and faster in others, and there is no cure for the disease.
There are two types of AMD. In dry AMD, which accounts for about 80% of cases, parts of the macula thin as small clumps of protein called drusen form. There is no treatment for late-state dry AMD. In wet AMD, which is rarer, new blood vessels grow under the retina and leak blood and fluid.
Research and future studies
Patnaik, along with fellow ophthalmology researchers, and Wendy Kohrt, PhD, professor of geriatric medicine and associate director of the Ludeman Family Center for Women’s Health Research, are digging into potential links between AMD and menopausal hormone therapy with the help of the Sue Anschutz-Rodgers Eye Center’s AMD registry, which has been collecting data for over a decade.
In new research published in the Journal of VitreoRetinal Diseases, the CU Anschutz investigators used the registry to evaluate the relationship between self-reported menopausal hormone therapy use and conversion to advanced forms of AMD among female patients.
Their findings in this study suggest there was not an association between use of menopausal hormone therapy and an increased risk of AMD progression. Limitations of the study and results from a previous study, which in some ways conflict with these findings, tell the researchers there’s room for more study in this area, Patnaik says.
“We have a cursory measure of hormone therapy use,” she says. “When patients are recruited into the registry, we ask whether they have a history of using these therapies, but we don’t have information on how long they’ve been taking these therapies, the dosage they are taking, or the type of hormone therapy.”
Diving further into the relationship between AMD and menopausal hormone therapy may require that type of data, which Patnaik says is possible to study if collected. In a previous cross-sectional study, the researchers looked at patients recruited into the registry with different types of AMD and then compared them to a group of controls — patients who didn’t have AMD.
“There, we saw a very protective effect of using menopausal hormone replacement therapy and having AMD,” Patnaik says. “While we felt there was a strong association, there are still challenges with cross-sectional studies. There could have been a recall bias among patients, so the patients with AMD may be more or less likely to remember if they were on hormone therapy versus controls, and then there could also be inherent differences among the AMD and control groups that impact this relationship.”
Patnaik says she and her fellow researchers expected to find similar results to this first study by looking strictly at the registry and whether the use of menopausal hormone therapy is protective of AMD progression.
“Actually, we found no difference in risk of progression in regards to hormone therapy use,” she says.
The sum of the two studies means there’s an opportunity to dig deeper. “For now, there’s a big question mark as to whether hormone therapy influences risk of AMD,” Patnaik says.
Enhancing patient confidence
For Kohrt, who specializes in studying women’s health, the research on AMD and menopausal hormone therapy is a big step in the right direction, especially after decades of misinformation and limited research on menopause and hormone therapy and its impact on health.
“We know that estrogen is very important for regulating things like vascular function, which affects cardiovascular disease risk. We know that it affects propensity to gain weight, and we know that it has an important role in mediating risk of osteoporosis,” Kohrt says. “Studies like this one with ocular health help us learn more about sex hormones and what they mean for our health.”
The research is also important for female patients considering using menopausal hormone therapy and the advice they seek from physicians. Kohrt says doctors may sometimes unknowingly invoke fear of using these therapies. In the mid 1990s, research on hormone replacement therapy was chilled due to a belief that it caused breast cancer. Now, research has shown that risk to be much more nuanced.
“It’s got to trickle down into the education of our physicians,” she says. “I am encouraged by the resurgence of funding and focus on researching women’s health. We must pay attention to this and make sure we are studying sex differences, because men and women don't necessarily respond the same to interventional therapeutics.”
