An off topic post but one worth sharing. Until not too long ago, I was a triathlon / marathon / cycling / swimming coach and among those I helped succeed in their athletic endeavors was a triathlon team of athletes with visual impairments. The few that I coached each had different causes of blindness: one was born without sight, two with macular degeneration (loss of central vision often leading to complete blindness), another with the opposite of macular degeneration (the name escapes me but the loss of peripheral and night vision more frequently leading to complete blindness), and another, a former USN sailor lost his vision when his step-mother killed his father, shot him in the head trying to kill him and then killed herself. There were a few others I provided guidance for, but this was the core group.
The group did a variety of triathlons ranging from the sprint distance Malibu Triathlon (0.5 mi swim, 18mi bike, 4mi run), Escape from Alcatraz Triathlon (1.5mi swim, 18mi bike, 8mi run), and Wildflower Olympic Triathlon (1500m swim, 40k bike, 10k run). (I guided the fastest of the group through those races... we were averaging 6min/miles for the faster run portions... that kid is fast.) Their goal, documented in the upcoming documentary "Victory Over Darkness", was to complete an Ironman Triathlon (2.4mi swim, 112mi bike, 26.2mi run). They did this at Coer d'Alene (Ironman Idaho). This teaser should give you an idea of the upcoming movie.
I don't know when it'll be released. Up to date info should be available here.
If ever thought getting out for a run, swim, or bike was just too tough, consider doing it with severe or complete visual impairment...