Context : Daniel Kish (born 1966 in Montebello, California) is an American expert in human echolocation and President of World Access for the Blind, a non-profit founded in 2000 to facilitate ``the self-directed achievement of people with all forms of blindness'' and increase public awareness about their strengths and capabilities. 
Question : What was Daniel Kish's medical condition near the end of his life?
blindness