Little House on the Prairie S05E21 - Enchanted Cottage

Mary begins to see a bright light every time she stands in front of a window. The possibility of regaining her vision is there, but she and Charles must pay a visit to her eye specialist in Sleepy Eye to get a definite answer. While they are away, Laura and Albert start working on a surprise project for Mary, and the Ingalls family becomes concerned about Adam's recent strange behavior.