Ophthalmology / Cornea / Apoptosis / Humans / Male / Photorefractive keratectomy / Clinical Sciences / Middle Aged / Optometry and Ophthalmology / Corneal Opacity / Public health systems and services research / Necrosis / Excimer Laser / Photorefractive keratectomy / Clinical Sciences / Middle Aged / Optometry and Ophthalmology / Corneal Opacity / Public health systems and services research / Necrosis / Excimer Laser