Structure of the Eye (i)
Retinitis pigmentosa (RP) results in the gradual degeneration of the light sensitive cells of the retina. The retina is the light sensitive tissue inside the eye in which the first stages of seeing take place. For those not familiar with the structure of the eye, think of it as similar to a camera, which has a lens at the front, the purpose of which is to focus light onto a light sensitive film inside the camera towards the back. In a similar way, the eye is a sphere, with a lens at the front which focuses light onto a light sensitive tissue, which lines the inside of the back of the eye (Figure 1). This tissue is called the retina and it is the area affected by all types of RP. Over time the retina ceases to function and then dies away. The lens at the front of the eye is normally completely transparent but can become opaque with increasing age or when there are diseases of the eye. An opaque lens is termed a cataract. A cataract can be treated by cataract surgery in which the opaque natural lens is replaced by an artificial lens. Many elderly individuals develop cataract as a result of ageing changes in the lens. Patients with RP can develop cataracts at a younger age. The results of cataract surgery are usually excellent (Cataracts).