Why does temperature impact my vision?

Here is My Question:
When I get extremely hot, it ooks like I'm looking through very thick fog but when I cool down my vision goes back to normal. Should I be worried and go see a doctor?

Answer:
What you describe it called Uhtoff's phenomenon.

I am assuming you have multiple sclerosis and that you previously had optic neuritis.
After someone has had an attack of optic neuritis (and recovered) there can be transient episodes of blurry vision when the core body temperature rises and the vision recovers as the body cools off.

This is not another attack of optic neuritis but rather a well described phenomenon (Uhtoff's phenomenon). The rise in body temperature is not causing further or new damage to the optic nerve. Rather the rise in temperature is unmasking the prior damage to the optic nerve which occurred when the optic neuritis happened previously.

If you have not seen an ophthalmologist or neuro ophthalmologist recently it is probably a good idea to follow up with one in clinic but it is not urgent.

Benjamin Osborne, MD
Director, Neuromyelitis Optica (NMO), Neuro-Ophthalmology Clinics and MS/Neuro-immunology Fellowship Director
Associate Director of the NIH/Georgetown Neurology Residency Program
Medstar Georgetown University Hospital