Ophthalmology is a branch of medicine dealing with the diagnosis, treatment and prevention of diseases of the eye and visual system. The eye, its surrounding structures and the visual system can be affected by a number of clinical conditions. Ophthalmology is a branch of medicine dealing with the diagnosis, treatment and prevention of diseases of the eye and visual system. The eye, its surrounding structures and the visual system can be affected by a number of clinical conditions. Ophthalmology is a branch of medicine dealing with the diagnosis, treatment and prevention of diseases of the eye and visual system. The eye, its surrounding structures and the visual system can be affected by a number of clinical conditions.