Ophthalmology• Updated 21 October 2026
OCT Scan (Optical Coherence Tomography)
A quick, painless light-based scan that shows the layers of the retina in detail.
Results: Same day
Quick Summary
Primary Purpose
To diagnose and monitor macular degeneration, diabetic macular swelling and glaucoma.
What It Measures
Retinal thickness and layers.
Preparation
Dilating drops may be used.
Overview
OCT doesn't touch the eye.
It's essential for monitoring eye injections.
What It Measures
Retina
Swelling, fluid and thinning.
Optic nerve
Nerve fibre layer.
How It's Performed
- 01
Position
Chin on a rest.
- 02
Scan
Look at a light for a few seconds.
- 03
Done
Minutes.
Sources and further reading
Last updated 21 October 2026. For more detail, see these trusted health organisations.
- Glaucoma Tests(opens in a new tab) · MedlinePlus, US National Library of Medicine