Wiktionary
out of sight, out of mind
alt. When something is not nearby, it is forgotten about. prov. When something is not nearby, it is forgotten about.
Wikipedia
Out of Sight, Out of Mind
"Out of Sight, Out of Mind" was the 101st episode of the M*A*S*H television series, and the fourth episode of the fifth season. Written by Ken Levine and David Isaacs and directed by Gene Reynolds, it first aired on October 5, 1976 and was repeated December 28, 1976. It features Hawkeye having to contend with sudden blindness after an accident.