Doctors advise caution on vision risks linked to diabetes, weight-loss drugs

Medical experts have urged caution over potential eye-related risks associated with GLP-1 receptor agonists, a class of drugs increasingly used to treat obesity and type-2 diabetes.

Medications such as semaglutide (sold as Ozempic and Wegovy) and tirzepatide (Mounjaro) have gained global attention for their effectiveness in improving blood sugar control and aiding weight loss.

Their use in India is expected to rise following the expiry of semaglutide’s key patent on March 20, potentially paving the way for more affordable versions. While this could expand access, doctors warned it may also lead to unsupervised or inappropriate use.

Emerging concerns

Ophthalmologists point to growing evidence that these drugs may be linked to an initial worsening of diabetic retinopathy and, in rare cases, non-arteritic ischemic optic neuropathy (NAION) – often described as an “eye stroke” that can cause sudden, painless vision loss.

Experts said rapid reductions in blood sugar levels triggered by these therapies may temporarily affect blood flow to the retina and optic nerve in some patients.

Evidence and risk factors

Although long-term data is still evolving, global agencies such as the World Health Organisation and the European Medicines Agency have recognised NAION as a rare potential adverse effect.

The risk appears higher among individuals with pre-existing diabetic retinopathy, hypertension, sleep apnoea, or certain optic nerve characteristics, though overall incidence remains low.

Call for careful use

Rohit Shetty, Director of Narayana Nethralaya, said the benefits of these drugs must be balanced with careful clinical judgment.

“These medications are effective when used appropriately, but their increasing use means we must be more vigilant in identifying patients at higher risk of complications,” he said.

He stressed the need for detailed pre-treatment evaluation. “Assessing both systemic and ocular health – particularly the presence of diabetic retinopathy or vascular risk factors – helps in stratifying patients and choosing the most appropriate therapy,” he said.

He added that high-risk patients may need closer monitoring, including baseline and periodic retinal examinations. “In some cases, tighter follow-up or even reconsideration of therapy may be required, especially during the early phase when blood sugar levels change rapidly,” he said.

Need for integrated care

G. V. Divakar, past president of the Bangalore Ophthalmic Society and consultant at Divakars Speciality Hospital, said GLP-1 receptor agonists have been linked to rare but serious ocular complications.

“These include non-arteritic anterior ischemic optic neuropathy, which can result in permanent vision loss, as well as progression of diabetic retinopathy,” he said, emphasising the need for regular eye examinations and follow-up.

“A collaborative approach between endocrinologists and ophthalmologists is key to minimising risks while ensuring patients benefit from these therapies. With wider access expected, patients should not self-medicate. Treatment should only be undertaken under proper medical supervision,” he said.

Rajesh R., consultant – Vitreo-retina and Ocular Oncology at Sankara Eye Hospital, said while these drugs are effective, awareness of potential risks is crucial.

“Rapid improvement in blood glucose levels can sometimes lead to a temporary worsening of diabetic retinopathy. This is not unique to these drugs and can occur with any form of intensive glucose control,” he explained.

Most vulnerable

Patients with long-standing uncontrolled diabetes or advanced retinopathy are particularly vulnerable. Some visual disturbances reported during treatment may be linked to fluctuations in blood sugar rather than a direct drug effect, he said.

Dr. Rajesh also pointed out that isolated reports of optic nerve-related vision loss are still under investigation. “At present, there is not enough evidence to establish a clear causal relationship, and further research is needed,” he said.