Optical Coherence Tomography (OCT)

I was looking on the bbc website and I found a report on how OCT has been found to be useful in finding out how far along MS (multiple sclerosis)  has developed caught my eye as one of my family members has  MS.

OCT is an eye scan which works similarly to an unltrasound, the main difference is that it uses infrared light waves instead of normal soundwaves.  The infrared light waves are used to find the distance of eye structures.  It has 25 times better resolution than other eye scans and machines and it allows you to see the retina in a large amount of detail as well as the layers of the retina.  This means that you are able to see if there is a thickening or thinning of the retina.  OCT also allows for the nerve fibres in the retina to be viewed and shows any damage to them.

MS is caused by recurrent immune reactions in the spinal cord and brain.  The myelin layer that covers the nerve fibres (axons) is damaged by these reactions which leaves the nerve fibres open to damage.  Due to the damage to the nerve fibres people with MS  experience problems with balance, vision and usually movements. MS can be diagnosed through MRI scans as these show up any scar tissue in the brain.  The scar tissue is caused by new layers of myelin forming over the nerve fibres, however these are usually thinner and weaker and so are more easily damaged.

However, the problem with MRI scans is that we aren’t quite sure at which stage of MS these scar tissues begin to appear visibly and OCT is thought to be able to detect one of the earlier signs of MS.  This is because the nerve fibres in the brain have the myelin layer over them but the nerve fibres in the retina don’t have this layer.  It has been suggested that therefore the nerve fibres in the retina will show damage first because there is nothing to protect them.  This could allow for an earlier diagnosis which would allow the person to undergo treatment to slow down the disease (unfortunately there is no cure for MS yet).

Nonetheless, this trial has only been done on 164 people which did show that the ones that had earlier and more active MS had thinning of the retina.  OCT could also be used to find out how fast the disease is progressing as well as helping to diagnose people with it, this could help improve the quality of life for some people as they could have the possibility of changing the treatment they are on to see if that will slow down the disease anymore.  However more trials need to be done on a larger number of people to find out whether OCT really does help show the extent of MS.

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