Guide · 3D OCT
What is an OCT scan, and do I need one?
A photograph of the back of your eye shows the surface. An OCT scan shows what’s underneath, layer by layer. That’s where glaucoma and macular disease start, years before you’d notice — which is the whole point.
What it is
Optical coherence tomography: a beam of harmless light scans across the back of the eye and the reflections are assembled into a cross-section of the retina and optic nerve — like an ultrasound, but with light, and to a resolution of about a hundredth of a millimetre. Ten seconds per eye, nothing touches you, nothing to feel.
What it finds
Glaucoma, by measuring the nerve fibre layer, which thins years before your vision field changes. Macular degeneration, by showing fluid or deposits under the macula before they distort your sight. Diabetic swelling of the retina. And it gives a baseline, so the next scan shows change — which is often the most useful thing.
Who needs it
Anyone over forty, because that’s when glaucoma risk starts to climb and the scan is the best early warning there is. Anyone with glaucoma or macular degeneration in the family. Anyone diabetic. Anyone with a high prescription. And anyone who’d rather know.
If you’re twenty-five with no family history, you probably don’t need it every time — but a first scan gives a baseline that’s worth having.
What it costs
Included in the £95 Gold examination and the £195 Platinum. £25 as an add-on to an NHS test. Wherever you have it, ask for the scan to be explained to you on the screen — that’s where its value is.
The short version
- A cross-section of the layers behind the retina, in ten seconds
- Finds glaucoma, macular and diabetic change years before symptoms
- Over forty, family history, diabetes: yes
- Included in Gold (£95); £25 on an NHS test