Optical Coherence Tomography (OCT) is a non-invasive imaging test that uses light waves to take cross-sectional pictures of your retina. With OCT, each of the retina’s distinctive layers can be seen with details discernible to micrometres.
We usually take OCT images of your macular and of the optic nerve at your appointment. By imaging the macula we can see if you have any signs of macular degeneration, macular holes or epi-retinal membrane. These often can’t be seen by standard imaging.
By imaging the optic nerve we can look at the thickness of the nerve fibres as they go into the nerve. When we get glaucoma this damages the nerve fibres and they die, the thickness of the nerve fibres is reduced.
With standard OCT machines this thickness is compared to a database of normal to see if the nerve looks like one with glaucoma.
Our new Heidelberg OCT can also do this but has the added bonus of having an inbuilt eye tracker. With the eye tracker we can directly compare images from year to year to see if there has been a reduction in your nerve fibre layer, comparing you to yourself rather than to a database. This allows us to identify glaucoma earlier.