Eye health · September 5, 2026 · 1 min read

What an OCT scan shows

A two-second scan that sees beneath the surface of the retina — and why we keep the images.

Reviewed by the optometrists at Marlow & Finch Opticians

Optical coherence tomography uses light to build a cross-section of the retina, layer by layer, a little like an ultrasound.

Earlier answers

OCT can show thinning of the nerve fibre layer in glaucoma, fluid in macular degeneration and swelling in diabetic eye disease, often before they affect your vision.

Comparison is the point

A single scan is useful. Two scans a year or two apart are far more powerful, because we can see change rather than guess at it. That is why we keep every image.

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