Eyes
Last Thursday I saw an optometrist about my persistent changes (or as it seemed, worsening) of my vision. After having a "corneal topography" (essentially, staring into a tube full of bright, red, concentric circles in a bright yellow matrix while holding my eyes open really wide), the doctor determined that I have Keratoconus. (More info from the National Keratoconus Foundation.)
I'm told the remedy is hard contact lenses. And I was just getting used to the spectacles...