Optical Coherence Tomography (OCT) is a scan that measures the thickness of the lining at the back of the eye – the retina.
In a trial involving 164 people with MS, those with thinning of their retina had earlier and more active MS. Larger trials with a long follow up are needed to judge how useful the test might be in everyday practice.
Unlike nerve cells in the rest of the brain which are covered with protective myelin, the nerve cells in the retina are bare with no myelin coat. Experts suspect that this means the nerves here will show the earliest signs of MS damage