An ophthalmic surgeon on how weight-loss drugs affect eye health

Moorfields Eye Hospital has published a new page on its website providing insight on the eye health risks and benefits of GLP-1 agonists.

The use of GLP-1 medications – such as Wegovy, Ozempic and Mounjaro – for weight management has increased in recent years.

Following the rising popularity of these drugs, research explored potential associations between GLP-1 agonists and the risk of certain eye conditions – such as Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION) and age-related macular degeneration (AMD).

OT spoke with Moorfields Eye Hospital consultant ophthalmic surgeon, Sharon Heng, about why the resource was developed and what optometrists working in practice should know about weight-loss medications.

Why did you decide to develop this digital resource on GLP-1s and eye health?

There has been a great deal of discussion about GLP-1 medications, and their potential effects on not just the eyes but different parts of the body. We've also seen a huge increase in the use of these medications, both for diabetes and weight loss management.

As eye specialists, we felt it was important to provide members of the public with very clear, balanced, and evidence-based information about what we currently know. We want people to understand both the potential benefits and possible eye-related harm without causing them unnecessary alarm.

The evidence in this area is emerging very quickly. Some associations are becoming much clearer. Some associations are remaining uncertain and unclear. We want to share with the public what has been confirmed and what needs to be better evaluated, as well as giving them the knowledge they need when they use this treatment.

What are the key messages that healthcare practitioners should convey about GLP-1 medications?

The most important message is that we need to see the eye health risks in the context of the overall health benefits of this medication. For example, for someone with diabetes, obesity, or significant cardiovascular risk, the systemic benefits of treatment are very important.

Decisions about treatment therefore need to be balanced and weighed against the individual overall health risk profile and benefits, rather than just looking at the eye in isolation.

One of the eye conditions that has received considerable attention is NAION. In the UK, the Medicines and Healthcare products Regulatory Agency considers NAION to be a very rare potential adverse effect of semaglutide [a form of GLP-1 agonist]. NAION affects up to one in 10,000 people taking GLP-1s. It typically presents with painless vision loss or deterioration in vision, usually in one eye.

For associations with other eye conditions, the evidence remains mixed at the moment. We have some information that says it can potentially worsen diabetic retinopathy and diabetic macular oedema, but there is also known paradoxical worsening of the above with tighter glucose control.

If diabetic patients present with floaters, distortion, blurring of vision or loss of central vision, they should be referred to an ophthalmologist. Other symptoms to look for include loss of visual fields and blind spots.

What should optometrists working in practice be aware of? What steps should they take when seeing patients?

The key message is to be aware of potential ocular effects of GLP-1s. When a GP or an optometrist is taking a history, it is important for them to be aware of whether a patient is taking GLP-1s and what type they are taking.

They should also consider any symptoms that may be linked to this medication. Any sudden or rapidly worsening vision or missing area of vision, especially in someone with diabetes, should be referred to an ophthalmologist. Symptoms may also include new distortion or significant blurring and floaters.

What have you observed in clinical practice following the increasing use of GLP-1 medication?

One very practical change is we get a lot of emails now asking us whether a patient can start on GLP-1 medication, especially if they’re diabetic. That shows us that there is a level of concern among the public about this medication. When we are asked whether patients with diabetes can start this medication, the answer is yes – we can monitor the eyes closely.

We have had patients stopping the use of GLP-1 medication because of concerns over their eye health. We would ask that patients speak to their prescribers or GP prior to stopping the medication. We are also encouraging diabetic patients to attend their diabetic screening and see their ophthalmologist if they develop any eye symptoms.

I think there is a level of awareness and concern now among members of the public and healthcare professionals about ocular effects. The only proven adverse effect at the moment is NAION. It’s important that members of the public have a more balanced view of the medication, and that it is evidence-based.