The macula is the most sensitive part of the retina, the light-sensitive covering on the back of the eyeball, explains Dr. Alan Glazier, an opthalmologist based in Rockville, Md.
"The small spot [of the macula] is responsbile for most of your vision. It allows you to see detail, to read, recognize faces, and drive," he says. When the macula degenerates, you have difficulty performing these tasks.
At this point, Klee can still read, but only in size 16 font or larger and she uses a cane to help her navigate at night, as her condition affects her night vision.
"I was in denial for a while, but I can't really hide the fact that I can't see that well. I will never be able to drive, I can't recognize faces, and that kind of hits me hard sometimes," she says.
Klee attended a school for low vision after high school that taught her Braille and other skills to help her live independently given her degenerating vision.
"I've had so much support from my family and friends and now from the blind community," she says, and this has helped her get through the ups and downs of her disease.
Though he has not examined Beck, Glazier felt that it was most likely, given his symptoms and age, that he also suffers from vitelliform macular dystrophy, of the adult-onset variety.
"If it is vitelliform, then there is no treatment, which is probably why he's so devastated," he says, referring to Beck's tearful explanation of his future loss of vision.
Beck sought solace in his faith and also in humor. He tried to make light of his prognosis in Saturday's speech, bemoaning the fact that he loves to read but will be "too darn lazy to learn Braille."