Did you ever read the story of Beck Weathers - tried to climb Mt Everest the year it all went to hell and a handbasket? (1996). (Jon Krakauer, "Into Thin Air")
Beck had had eye surgery prior to leaving on his trip - got up to 30 million thousand feet (or whatever it was) and the altitude started messing with his sight - to the point where he could no longer continue because he couldn't see.
He ended up stopping (I believe, below the Hillary Step) and the expedition leader told him to stay there, not move, and he'd pick him up on the way down.
Unfortunately, the expedition leader stayed too long on the summit with a third-try client and they both perished. He never came back for Beck.
Beck ended up in a group of climbers who made it back down to the saddle where they were supposed to camp, but in white out conditions couldn't find the tents. They ended up sheltering in place until Anatoly Boukreev (sp?) came to fetch them one by one. By then, a japanese climber had already perished and Beck was considered too far gone to be able to be helped, so was left.
The following day he made it back to the tents, horribly frostbit - they said he looked like a zombie.
Expecting to never be able to get him off the mtn, they were actually successful enough to get him to the top of the Khumbu Icefall (complicated technical area that has to be traversed in part on ladders lashed together over crevasses). They couldn't get him any further and figured, once again, he was done for.
Beck's wife, Peach - back in TX - got on the phone and arranged for a never-before-tried helicopter rescue with someone from the Nepali air force. They had to take all the seats out of the helicopter to make it light enough that it could still take off again when it landed to pick him up.
Beck survived - losing a hand, fingers, toes, and his nose (they grew him a new one on his forehead). Lucky man. All because of eye surgery.