Uhthoff’s Phenomenon

Spoiler alert: your body really gets confused thanks to MS. One of the ways your body shows it is Uhthoff’s Phenomenon, which is blurry or reduced vision caused by overheating. A small rise in temperature is enough to block or slow the conduction of a nerve impulse along a nerve that has suffered demyelination from MS damage. This can make your existing symptoms worse, but once your body temperature returns to normal, the symptoms generally improve