Onanism. See Masturbation
Opacity. Opaque condition of parts of the eye, causing blindness.
Opalescent. Reflecting a milky light.
Opaque. See Opacity.
Ophthalmia. Inflammation of the eye.
Ophthalmic. Belonging to the eye.
Ophthalmoscope. An instrument for examining the inside of the eye, for diagnostic purposes.
Optic Nerve. The nerve connecting the brain and eye, and employed in the sense of sight.
Organic. Pertaining to the structure of an organ.
Orifice. Opening or mouth.