Retinitis pigmentosa is a group of hereditary disorders characterized by progressive deterioration of vision due to dysfunction, cell loss, and eventual atrophy of the retina Night blindness is usually the presenting feature, with gradual deterioration of retinal rods and cones Initially there is loss of peripheral vision, which is of gradual onset and can progress to tunnel vision. Eventually, there is loss of central visual function, in most cases The age of onset of visual impairment in the different forms of retinitis pigmentosa ranges from infancy to late adulthood The condition is bilateral and symmetrical in the majority of cases Ophthalmoscopy shows typical 'bone spicule' (pigment clumps in the shape of bone corpuscles) in the mid-peripheral retina with retinal arteriolar attenuation and a pale, waxy optic nerve head An electrophysiologic test, the electroretinogram, which detects photoreceptor function, is abnormal even in early stages of the disease Vitamin A may slow the progression of retinal degeneration, and acetazolamide may be of some benefit early on; all other therapies are still experimental.........reference : First Consult.