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Retinitis pigmentosa is an inherited eye disease that affects night vision and peripheral vision. Photoreceptor cells in the retina degenerate, causing a breakdown of rods and cones, leading to night blindness and loss of lateral vision. The disease is recognized in childhood and varies in degree of vision loss.
Retinitis pigmentosa is an inherited eye disease that affects a person’s ability to see at night. It also affects their peripheral or side vision. This genetic disorder begins with decreased night vision but also progresses to decreased peripheral vision. The rate at which a person’s vision decreases is usually related to their genetic makeup, so it varies between people.
What actually happens is that the photoreceptor cells in the retina degenerate and die. As they degenerate, the patient loses more and more vision as the photoreceptors are the cells that capture and process light.
Photoreceptor cells consist of rods and cone cells. Rods help people see images from peripheral vision and see images in dark or dimly lit areas. Cones sit in the center of the retina and help people see visual detail and color. Working together, the rods and cones convert light into electrical impulses that are transmitted to the brain, the actual place from which people ‘see’.
In retinitis pigmentosa there is a gradual breakdown of the rods and cones. The rod cells usually degenerate first causing rod-cone dystrophy, which in turn causes night blindness. Patients with night blindness do not adapt well to dark, dimly lit environments.
As the disease progresses, patients begin to lose lateral vision and may experience a circle of vision loss in their mid-periphery with small islands of vision in their far periphery. Other patients have tunnel vision, as if they are looking at the world through a tube. Some patients retain a small amount of central vision throughout their lives.
Another form of retinitis pigmentosa, called conical dystrophy, affects the patient’s central vision first. This cannot be corrected with glasses or contact lenses. The sufferer may also lose the ability to perceive color. As the disease progresses, patients also lose peripheral vision and develop night blindness.
The disease is usually recognized in childhood and the degree of vision loss varies with the patient.
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