one eye; one of one's eyes
being blind in one eye; person who is blind in one eye
「片目」 has another reading with different meanings.
片眼で見ると視界が狭い。
When you look with one eye, the field of vision is narrow.
彼は片眼に眼帯をしている。
He is wearing an eye patch on one eye.
事故で片眼を失った。
He lost one eye in an accident.