Ophthalmology is the medical specialty dedicated to the study of the eye's structure and function, and to the diagnosis and treatment of diseases affecting them.
In a normal eye, the cornea and the lens focus the light rays entering the eye to a single point close to the retina. The retina or the light sensitive tissue in the back of the eye, converts light impulses into nerve impulses. The nerve impulses move along the optic nerve to the brain, which interprets the impulses allowing these persons to "SEE". Three primary types of refractive errors might occur. These are Myopia (near sightedness), Hyperopia (far sightedness) and Astigma.