OCT scan

An optical coherence tomography (OCT) scan takes a detailed 3D picture of the layers at the back of your eye, using a harmless beam of light. It can show changes in conditions such as glaucoma, macular degeneration and diabetes years before you would notice them. The scan itself takes a few minutes and is painless.

Book it by itself, or add it to an NHS or private eye test. Allow 15 minutes. It costs £35, paid in store.

What to bring

• Your glasses and any contact lenses you wear
• Your last prescription, if you have it
• A list of any medicines you take