A recent population-based study published in Acta Ophthalmologica evaluated the potential link between postmenopausal hormone replacement therapy (HRT) and eye health—specifically the incidence of glaucoma.
I have to ask … why look at this possible connection?
While postmenopausal HRT has been widely used to manage symptoms like hot flashes and bone loss, its role in eye health has remained less clear.
The challenge is that hormone therapy isn’t a single, uniform exposure. It varies widely in formulation, dosing, duration, and timing relative to menopause, all of which can influence how it affects ocular tissues.
- As a result, studies have reported mixed results based on these differences in exposure and patient populations.
- In fact, some earlier research has suggested that estrogen might help protect the optic nerve, with evidence linking estrogen to retinal ganglion cell (RGC) survival and intraocular pressure (IOP) regulation
- And other findings have pointed toward increased or variable risk depending on how hormone therapy is used.
Go on …
That variability makes it difficult to compare outcomes across studies or draw consistent conclusions—which is why the relationship between hormone therapy and glaucoma risk has remained unsettled.
Got it. So how did this study examine the risk?
To move beyond smaller or conflicting datasets, researchers used national health registry data in Finland.
- These systems track diagnoses, prescriptions, and healthcare use across large populations, making them useful for long-term risk analysis.
In this case: The study analyzed prescription records and clinical outcomes of a group of postmenopausal women over several decades, allowing investigators to evaluate not just whether patients used HRT, but how long they used it and which hormone types were involved.
Tell me more about these women.
The researchers started with nearly 400,000 women aged 50 and older. After excluding anyone with a prior glaucoma diagnosis or related procedures, they narrowed the cohort down to 6,576 women.
Of those, 1,096 developed glaucoma and were classified as cases. Each case was matched with five controls of the same age, resulting in 5,480 controls.
The researchers also adjusted for key variables like diabetes, statin use, and socioeconomic factors to better isolate the effect of hormone therapy.
What did the data show about HRT and glaucoma risk?
After adjustment, the results were consistent across the board: all forms of hormone therapy were linked to higher glaucoma risk.
- Estrogen-only therapy: OR 1.33
- Progesterone-only therapy: OR 1.25
- Combined therapy: OR 1.19
In other words, regardless of formulation, hormone therapy use was associated with a modest but measurable increase in glaucoma risk.
The same trend held up in subgroup analysis, particularly for primary open-angle glaucoma, where estrogen-only therapy remained significantly associated with increased risk.
How risk varied by hormone type and duration.
One of the more telling findings was how risk changed over time. Longer exposure to estrogen was associated with higher glaucoma risk, suggesting that duration, not just use, matters.
What limitations may affect how we interpret these results?
Even with a large dataset, there are limitations to keep in mind.
First, this is an observational study, meaning it can show association but not prove causation.
Second, glaucoma diagnoses were based on registry data and treatment eligibility rather than standardized clinical testing like visual fields or OCT. That introduces some variability in how cases are defined.
Finally, the study population is specific to Finland, which may limit how broadly the findings apply to more diverse populations or healthcare systems.
Why do these findings differ from earlier research on estrogen?
The authors themselves stopped short of making definitive claims, noting that hormone therapy “may increase the glaucoma risk” while emphasizing that further research is needed to confirm the association.
That cautious tone is echoed in clinical coverage. Essentially, the findings are notable because they contradict earlier assumptions about estrogen’s protective role.
At the same time, experts aren’t treating this as a practice-changing conclusion yet. Instead, they’re viewing it as a signal; specifically, one that needs to be interpreted alongside prior research and validated in other populations.
The takeaway from an expert standpoint is measured:
- There appears to be an association
- But the underlying mechanism and clinical impact are still not fully understood
What does this mean for clinical decision-making moving forward?
This doesn’t mean avoiding hormone therapy altogether. Instead, it adds another factor to consider when evaluating patient risk.
Patients already at higher risk for glaucoma—whether due to age, family history, or vascular disease—may benefit from closer monitoring if they are on long-term HRT.
It also reinforces the importance of routine eye exams in postmenopausal patients, particularly those using hormone therapy over extended periods.
Take home.
This large registry-based study suggests that postmenopausal hormone therapy is associated with an increased risk of glaucoma, regardless of hormone type.
And while the findings don’t change practice overnight, they do shift the conversation. Hormone therapy is no longer just a systemic consideration; it may also be part of the long-term ocular risk profile.