What an OCT scan shows
You may have heard your optometrist mention an OCT scan, or seen one advertised. Here is what it is.
The short version
OCT (optical coherence tomography) uses light to make a detailed cross-section of the back of your eye. It is a bit like an ultrasound, but with light rather than sound. There is no contact with your eye, no drops are usually needed, and the scan takes a few seconds.
What it looks at
The retina at the back of your eye is made of layers, thinner than a hair in total. A photo shows the surface. An OCT scan shows what is beneath: the thickness and structure of each layer, the small dip at the centre of your vision called the macula, and the head of the optic nerve.
Why it helps
Seeing the layers lets your optometrist look for changes that cannot be seen from the surface. This is useful for:
- checking the health of the macula
- looking at the optic nerve, which matters for glaucoma
- keeping an eye on changes over time, since we can compare today's scan with the next
It does not give a diagnosis on its own. Your optometrist uses it with the rest of your eye test. If anything needs a closer look, we will refer you to your GP or an eye clinic and send them the scan.
Who might want one
Anyone can. People often choose one if they have a family history of eye conditions, have diabetes, are over 40, or want a baseline to compare against in future.
What happens
You sit with your chin on a rest and look at a light for a few seconds while the machine scans each eye. Dr Shah or Dr Okafor then goes through the pictures with you on screen.
Cost
An OCT scan is £35, added to a test or on its own. It is not part of an NHS test, so it is an extra you can choose. See our OCT scans page for more.
This is a demo shop; Clearview Opticians is fictional.