"He lost the sight in his right eye."
Translation:Ele perdeu a visão do olho direito.
Yep, you can say that too. Different from english, latin languages dont usually use possessive before parts of the body, but theres no objection on using them. We normally use definite article. She hurt her hand = "ela machucou a mão", but nothing wrong to say "ela machucou sua mão" / "ela machucou a mão dela", but we often understand it is being referred to the own person.