It is a genetic disorder in the eye, which affects the retina, and this disorder is a result of a defect in the light receptors of the retina.

Symptoms

·        Decreased or loss of night vision

·         Loss of peripheral vision gradually (tunnel vision).

·        Difficulty with color vision.

·        Vision decreases but not rapidly, it may last for years.

Treatment

There is no cure now for the disease but the doctors follow ways to delay progression of the disease.

·        Use sunglasses to protect the eyes from ultraviolet rays.

·        Eyeglasses and magnifiers, especially for early treatment.

·        Intensity of external light helps to improve vision.

·        Treatment with Vitamin (A) is beneficial for cases where this vitamin is lacking, but not for other types, and should only use as directed under medical supervision.