Blind descent

the long version

"Former Navy rescue swimmer Brian Dickinson was roughly 1,000 feet from the summit of Mount Everest ... when his Sherpa became ill and had to turn back, leaving Brian with a difficult decision: should he continue to push for the summit, or head back down the mountain? After carefully weighing the options, Brian decided to continue toward the summit ... Four hours later, Brian solo-summited the highest peak in the world, but the celebration was short-lived ... Suddenly, his vision became blurry, his eyes started to burn, and within seconds, he was rendered almost completely blind"--Amazon.com.