Retinitis pigmentosa (RP) consists of a large group of disorders resulting from a progressive loss of the rods and cones (receptor cells) in the retina. These are the cells that respond to light and send signals to the brain that enable us to see. More than 100 mutant genes have been identified as responsible for these hereditary disorders and there is considerable variation in onset and progression of symptoms. The disease usually is present as an isolated eye disease but syndromal forms also occur in which there is a similar disease of the retina in association with other disease elsewhere in the body.
Pigmentary changes in the retina have been seen in children as young as 6 months of age. By the middle of the first decade of life when children are old enough to express symptoms, many complain of difficulty seeing at night and maybe loss of side vision (tunnel vision). These symptoms gradually become more pronounced and loss of visual acuity worsens leading to blindness by the third decade of life.
Walking is often delayed and gait difficulties are evident by the second decade. Generalized weakness and wasting are usually present. Many individuals are unable to walk by the second or third decade. Fine touch is impaired. The muscle weakness leads to orthopedic deformities such as abnormal curvature of the spine.
This is a rare autosomal recessive disorder requiring two mutations in a gene. Parents are carriers only and do not have symptoms of the condition. However, when both parents are carriers, they confer a 25% risk of this condition to each child.
The diagnosis is made by collaborative efforts on the part of ophthalmologists and neurologists. The prognosis for a normal life is poor as there is progressive neurological and retinal generation leading to blindness and impaired physical abilities. Patients often live to adulthood but with severe handicaps. No treatment for this disease is available but physical therapy and low vision aids may improve quality of life in childhood.