In Little House on the Prairie TV Show, Mary Ingalls suffers eyesight problems and eventually goes blind in the season finale for season four, in the two part episode I’ll Be Waving As You Drive Away (Part One) and I’ll Be Waving As You Drive Away (Part Two).
In real life, the real Mary Ingalls was also blind, and this is also included in the Little House books. Her blindness was also a topic in the newspaper near her home at the time. The real Mary also does go away to school for the blind, although she attended the college for the blind in Vinton, Iowa and not the one as it appears on the television show.
In real life, Mary also never marries, as she does in the TV series.