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Study breakdown

Oral Semaglutide Linked to Reversible Blind Spots in Low-Light Vision: A Case Report

evidence
The takeaway

A 72-year-old ophthalmologist developed bilateral central blind spots visible only in dim light 17 days after starting oral semaglutide, which completely resolved two days after stopping the medication.

Complete resolution in 2 days

Central scotomata in both eyes that appeared 17 days after starting oral semaglutide disappeared entirely within 2 days of stopping the drug, with no structural damage found on comprehensive eye exams.

What the researchers found

A 72-year-old male developed bilateral, incongruent central scotomata (blind spots) under scotopic (low-light) conditions 17 days after initiating 3.0 mg daily oral semaglutide. The scotoma started in the right eye and expanded over several days before appearing in the left eye. Symptoms were only present in dim light and absent in daylight or artificial lighting. All symptoms completely resolved within 2 days of medication discontinuation. Comprehensive ophthalmologic evaluation including macular OCT, fundus photography, fundus autofluorescence, and Humphrey visual field testing revealed no structural abnormalities.

Why it matters

Semaglutide is one of the most widely prescribed medications globally for diabetes and weight loss. As millions of people take this GLP-1 receptor agonist, identifying even rare side effects is important for patient safety. This is the first reported case of scotopic central scotomata associated with semaglutide, and the rapid reversibility is clinically reassuring but warrants awareness.

How the study worked

This is a single case report. The patient — himself a board-certified ophthalmologist — self-reported symptoms and underwent a complete ophthalmologic evaluation after symptom resolution. The temporal relationship between semaglutide initiation, symptom onset, drug discontinuation, and symptom resolution was documented.

What this study cannot tell us

This is a single case report — the lowest level of clinical evidence. Causation cannot be definitively established from temporal association alone. The patient was unique in being an ophthalmologist who could precisely describe visual symptoms. The mechanism is unknown — no structural changes were found on imaging. It's possible this was coincidental or related to another factor.

How to read the evidence

This is a single case report, which provides the lowest level of clinical evidence. It establishes temporal association but cannot prove causation. However, the clear onset-discontinuation-resolution pattern is suggestive, and the patient's expertise as an ophthalmologist adds credibility to the symptom description.

When this study was published

Published in 2024, this case report is timely given the massive increase in semaglutide prescriptions for weight loss.

The bigger picture

As GLP-1 receptor agonists continue to be prescribed to millions of people for weight loss and diabetes, understanding the full spectrum of side effects becomes increasingly important. Visual symptoms have been reported with some GLP-1 medications (diabetic retinopathy concerns with semaglutide), but scotopic-specific central scotomata represent a novel finding. This case adds to the pharmacovigilance picture for this drug class.

Questions still open

  • What mechanism could explain semaglutide-induced scotopic visual changes without any structural retinal damage?
  • How common might this side effect be in the broader population, where patients may not notice subtle low-light visual changes?
  • Do other GLP-1 receptor agonists carry a similar risk of scotopic visual disturbances?

Common questions

Can semaglutide cause vision problems?
This case report describes a previously unreported visual side effect — central blind spots visible only in dim lighting — that appeared 17 days after starting oral semaglutide and resolved completely within 2 days of stopping. No structural eye damage was found. However, this is a single case and the side effect appears to be very rare.
Should I stop semaglutide if I notice vision changes?
If you notice any new visual symptoms while taking semaglutide, you should contact your prescriber. In this case, symptoms resolved quickly after discontinuation with no lasting damage. Your doctor can help determine whether the symptoms are related to the medication and whether it should be continued, adjusted, or stopped.

Read the original research

Reversible bilateral central scotoma under scotopic conditions associated with oral semaglutide.

American journal of ophthalmology case reports, 36, 102121

Citation

Bracha, Peter; Johnson, William; Chu, Sabrina; Davison, James. (2024). Reversible bilateral central scotoma under scotopic conditions associated with oral semaglutide.. American journal of ophthalmology case reports, 36, 102121. https://doi.org/10.1016/j.ajoc.2024.102121