Weight Loss Medicines and Eye Health: what dispensing opticians need to know

The rapid growth in the use of medicines for weight management has created a new consideration for eyecare professionals. Evidence has identified a very rare risk of non-arteritic anterior ischaemic optic neuropathy (NAION) associated with semaglutide, the active ingredient in Wegovy, Ozempic and Rybelsus.

NAION occurs when blood flow to the front of the optic nerve is reduced. It typically causes sudden, painless loss or deterioration of vision, usually affecting one eye, and visual loss can be permanent.

What does the evidence tell us?

In 2025, the European Medicines Agency’s (EMA) Pharmacovigilance Risk Assessment Committee reviewed clinical trials, post-marketing surveillance and published research and concluded that there was sufficient evidence to establish a causal relationship between semaglutide and NAION. NAION is now listed as a “very rare” adverse effect, meaning that it may affect up to 1 in 10,000 people taking semaglutide.

The UK Medicines and Healthcare products Regulatory Agency (MHRA) subsequently updated UK product information in February 2026. Its review estimated that semaglutide may approximately double the relative risk of NAION, equivalent to approximately one additional case for every 10,000 people treated each year.

The distinction between relative and absolute risk is important when discussing this with patients. A doubling of risk can sound alarming, but because NAION is uncommon, the absolute additional risk remains very small.

Research continues to develop. A large 2026 study of US veterans with type 2 diabetes found a 2.33-fold higher risk of NAION among patients starting semaglutide compared with those starting an SGLT2 inhibitor. However, the absolute occurrence remained low, approximately 0.29% compared with 0.13% over a median follow-up of 2.1 years. Other large observational studies have produced differing results, illustrating why continuing pharmacovigilance remains important.

It isn’t just about injections

The familiar description of these treatments as ‘weight loss jabs’ is becoming increasingly outdated.

In June 2026, the MHRA approved a once-daily tablet formulation of Wegovy (semaglutide) for weight management in the UK. This contains the same active drug associated with the NAION warning and is gradually increased to a maintenance dose of 25 mg daily.

In August 2026, the UK also became the first European country to authorise orforglipron (Foundayo), a once-daily oral GLP-1 receptor agonist, for weight management and type 2 diabetes.

It is therefore increasingly important to ask about weight management medicines generally rather than simply asking whether a patient uses a weight loss injection. The established regulatory NAION warning currently relates specifically to semaglutide. Other GLP-1 medicines should not automatically be assumed to carry the same established level of risk.

What should dispensing opticians do?

Dispensing opticians are well placed to identify patients who report unexpected changes in vision and to recognise when symptoms require escalation.

When taking a history, consider asking specifically about medicines used for weight management or diabetes, including tablets as well as injections. Particular attention should be paid to a patient taking semaglutide who describes sudden, painless loss of vision, partial visual loss, blurring or cloudiness of vision.

The MHRA advises that patients reporting sudden loss of vision, including partial loss, while taking semaglutide should be urgently referred for ophthalmological assessment. If NAION is confirmed, semaglutide treatment should be stopped; that medication decision should be made by the patient’s prescribing/medical team.

Patients taking semaglutide who have no visual symptoms should not be unnecessarily alarmed or advised to discontinue treatment. Instead, they can be reassured that the complication is very rare, while being advised to seek urgent eyecare should sudden visual deterioration occur.

The key message

As weight management medicines become increasingly commonplace — and move from injections to tablets as well — they should become a routine consideration within medication history-taking.

For dispensing opticians, the message is straightforward: recognise the medicines, understand the very rare risk, reassure appropriately, and know the red-flag symptoms that require urgent referral.