「弱視 」は英語で poor/weak eyesight と言います。
彼は弱視である - He's got poor eyesight / He's got poor vision / His eyesight is not very good など。He's = He has です。
彼は生まれながら弱視である - His eyesight has been bad since birth / He was born with poor/bad eyesight
このpoor は貧しいという意味ではなく弱いという意味です。
vision - 視力
bad eyesight - 視力が悪い