(Disclaimer: Yes, I will have this checked by a doctor, but I’m not really worried for reasons to be explained. But this thread is just to describe an interesting observation)
About seven years ago I underwent the Lasik procedure. Before that I was so extremely nearsighted that I could hardly find my way around my own house without my glasses, nor could I even read. Though both eyes were very bad, one was not as bad as the other so I couldn’t focus both on a page of text at the same time.
While I was and am happy with the Lasik outcome, my vision isn’t perfect. I have slight acuity issues which I have just learned are similar to Keratoconus. This is a degenerative disease of the cornea, although in my case I’m fairly certain that it’s merely a structural defect introduced during the surgery. It’s been this way ever since I had the procedure.
With keratoconus, you get multiple images that are all clear, but most are faint, and, at least in my case, I focus on the dominant image and pretty much forget about it. However, I recently realized that sunglasses, or the pair that I usually wear, seemed to exacerbate the keratoconus-like effect. It appears they do this by reducing the difference between the dominant and other images. I realized that while driving, when I was usually wearing these sunglasses, I was fine running familiar errands on familiar roads, but if I had to go to a new place, read addresses or freeway signs, I had trouble. I especially noticed this while driving in Baja; by the time I could read the sign it was too late to make the turn.
The interesting thing I just noticed today is that my other sunglasses don’t cause this problem. I probably shouldn’t even be wearing them as they are antique glass-lensed aviators probably of World War II vintage. The frames are gold filled, and I hadn’t been wearing them much. I didn’t like the fact that they have the old-fashioned temples that wrap completely around the ear, making them harder to put on and take off. But it appears that the dark green glass lenses don’t affect my vision nearly as much as the newer plastic ones.
I’m very happy I made this discovery! I thought I’d have to give up sunglasses, at least when driving in unfamiliar places, but that doesn’t appear to the case after all.
//TODO
(1) See an ophthalmologist
(2) Get another pair of sunglasses with glass lenses.