What member of the Ingalls family went blind at the end of Season 4?

At the end of Season 4, Charles brings his daughter to the optometrist as her eyesight worsens, and discovers that she will soon go blind. While Mary struggled with her growing dependency on others as she went completely blind, she later became a teacher in a school for the blind.

Asked by Rachel Bortles · Last updated 5 years ago · 1.3M views · SOURCE