Retinitis Pigmentosa is a genetic disorder which leads to progressive retinal degenerations or dystrophies. It affects the photoreceptor cells present on retina, and impairs the ability of retina to respond to light.The retina is the light-sensitive tissue at the back of the eye that contains photoreceptors and other cell types. It involves the breakdown or loss of photoreceptor cells- rods and cones. This inherited disease causes a slow loss of vision, beginning with decreased night vision and loss of peripheral (side) vision.
Rods cells which are mainly in the outer region of the retina degenerate first and are responsible for our peripheral and night vision. Death of these cells leads to loss of peripheral vision. When the retina’s more centrally-located cones cells are affected, the result is loss of color perception and central (reading) vision.
Retinitis Pigmentosa can be diagnosed at any stage, from infants to adults. In initial stage there is decreased peripheral vision due to decline of rods cells and in later stages cones cells also dies causing constriction of central vision, leading to blindness eventually.
Retinitis pigmentosa is a bilateral inherited condition that involves both eyes.It usually starts later in life and progresses to blindness.
If we look at the statistics the prevalence of Retinitis Pigmentosa is estimated at approximately 1 in 3,000 to 1 in 5,000 individuals. RP affects about 1.5 million people worldwide and is the most common of the retinal degenerations. RP is the leading cause of inherited blindness in the world. Also it was found that in India Prevalence of RP in South India appears to be alarmingly higher in comparison to those seen in other parts of India.
RP is inherited from parents. It is caused due to faulty genes. Mutated genes give the wrong instructions to photoreceptor cells, which leads to more or less production of proteins which are required by cells to function properly. Due to faulty genes cells do not work the way they should. Many genes are associated with it. Fault in any one can lead to RP.
This is why RP is described as a group of inherited retinal disorders. RP is often mentioned alongside other eye conditions with similar genetic causes and effects on vision, such as Leber’s Congential Amaurosis, cone and cone-rod dystrophies and Choroideremia.
RP can also be associated with other problems such as hearing loss. These rare conditions are referred to as RP syndromes.