After having difficulty focusing his eyes, Beck went to see an eye doctor and was told he could be blind within a year, or not, depending on the progression of his disease.
The announcement came during Beck's final keynote speech of his "American Revival" tour in Salt Lake City, Utah, and was used illustrate a point Beck was making about the blessings of God.
"After I stopped feeling sorry for myself, I truly came to a place which is the greatest blessing: Lord, if you need my eyes, they're yours. They were yours the whole time anyway. Thank you for letting me see as far as I have," he said.
But the Fox News talk show host may have been speaking figuratively when he referred to his possible blindness, as macular dystrophies, by definition, only result in the loss of macular, or central vision, leaving the peripheral vision intact.
"Macular dystrophies lead to a very slow, progressive deterioration of central vision," says Dr. Sophie Bakri, associate professor of Ophthalmology at the Mayo Clinic in Rochester, Minn. Dr. Bakri has not examined Beck but is an expert in vitreoretinal diseases like macular dystrophy.
"Although in the advanced stages, patients may be 'legally blind' and unable to drive or read the newspaper, their peripheral vision remains unaffected and they are able to see light, shadows and some large letters."
Beck could have any one of a number of forms of macular dystrophy, all with different symptoms and prognoses, but representatives for Beck refused to comment on the record about more specific details of his condition.
Given his age, 46, it is most likely that Beck has a form of retinal macular dystrophy, says Bakri, and unfortunately, there are currently no treatments for these disorders.
This means that it is likely the conservative commentator will slowly lose his central vision, his ability to recognize faces, to read, and to perform other tasks that require the ability to see detail.
Glenn Beck May Become Partially Blind
"With what we know now about his symptoms, the bottom line is that it appears he has a macular problem that has a risk of getting worse and damaging his vision," says Dr. Michael Marmor, a retinal specialist at Stanford University School of Medicine and clinical correspondent with the American Academy of Opthalmology.
The speed of his condition's progression, however, is unknown, says Bakri, as it varies from case to case, hence the prognosis of "you could be blind in a year, or not", as Beck reported.
Macular Dystrophy and Best's Disease
Vania Klee, 21, a student in Sacramento, Calif., has been experiencing the gradual vision loss of macular dystrophy since she was born.
"I wasn't diagnosed until I was five. [Then] I couldn't see very far, only five to 10 feet in front of me and I had consistent headaches because I was constantly straining my eyes."
Klee has vitelliform macular dystrophy, a genetically inherited form of dystrophy that affects the retina and causes progressive loss of central vision. When it strikes patients at a younger age, it tends to be more severe and is known as Best's Disease.
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."