ClinicSpeak: what does your neurologist look for when (s)he looks in your eyes?

Optic disc pallor a sign of previous optic neuritis #ClinicSpeak #MSBlog #webEDSS

"If you have MS your neurologist would have almost certainly looked into the back of your eyes. Why? In MS we are looking for the telltale signs of previous damage to the optic nerve; when there has been previous damage the so called optic disc looks pale. The optic disc is made up nerve fibres from the retina the past out of the back of the eye to form the optic nerve. If you have optic neuritis you lose nerve fibres and we can see this when we look into your eyes with an ophthalmoscope. The optic discs receives its blood supply from small arteries from the back of the eye; the amount of blood is proportional to amount of nerve fibres in the optic disc. The lower the number of nerve fibres the fewer blood vessels there are the paler the disc looks. Please remember red blood cells are red and give a health optic disc a pinkish colour."

"Did you know that with a typical attack of optic neuritis you lose about 20% of the nerve fibres in the eye? If you lose so many nerve fibres why isn't your vision so badly affected in that eye? That is simply because your visual system is able to compensate for the damage; it has spare capacity. Despite this most pwMS who have optic neuritis will know that although their visual acuity, or gross vision, maybe have recovered they have subtle deficits that we don't routinely test for. For example, colour vision is often abnormal; colours appear washed out. Contrast sensitivity is abnormal; you may have difficulty distinguishing between shades of grey. Depth perception is all over the place; you need binocular (both eyes) vision for accurate depth perception. If you have poor depth perception you may see things in 3D when they should be in 2d, you may have difficulty judging distances. You may also find that you are hypersensitive to bright lights or lights with certain wavelengths; I find a lot of pwMS become intolerant of fluorescent lights after an attack of optic neuritis."

"Why I am telling you all this? We are about to launch our web-EDSS and it requires you to know if your neurological examination is normal or not. Having optic disc pallor is one clinical sign that may affect the EDSS. We are in the process of reviewing all the visual assessment APPS available to see which one we is best at assessing your visual function. Once we have vetted an APP we will let you know this will then allow you to assess your own visual function."

"Please let me know if you find this sort of post of interest?"

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