"Weak eyesight" is a phrase used to describe when someone has difficulty seeing clearly. It means that their eyes are not able to see things well, and they may need glasses or contact lenses to help them see better. Full definition
Cursed with weak eyesight and near non-existent hearing, this large, lethal lizard uses flavor as a guide. (foodfreaks.org)
Orsino is like most of us senior citizens with a little weaker hearing, a little weaker eyesight, a bump here and there; but he is still accepting and loving and eager to be part of a family. (austinboxerrescue.com)
Another thing to keep in mind: hamsters» weak eyesight means they will often try to identify new things with their teeth. (smallanimalchanel.com)