Retinitis pigmentosa (RP) is a clinically and genetically heterogeneous group of disorders characterized by progressive loss of vision and night-blindness. Etiologically, the disorder can be classified as a cone-rod dystrophy caused by apoptotic changes in the photoreceptor cells of the eye. Clinically, affected patients begin to show the symptoms of nyctalopia and vision loss in early adulthood. The latter usually begins early on as a peripheral vision loss, resulting in tunnel vision. Over time, however, the condition may progress to include central vision loss as well. Photopsia, or the visual perception of flashes of light, is also seen in many patients. Although RP is usually found in isolation, it can also form a part of several syndromic conditions, such as Usher syndrome, Kearn Sayre syndrome, and abetalipoproteinemia.
RP is a fairly common disorder, affecting approximately 1 in 4,000 individuals. Although the disease is not curable, techniques are available to ameliorate the condition. Night vision difficulties can be eased with the help of ocular devices. Clinical trials are underway to test new treatment strategies, including the use of vitamin A and omega-3 fatty acids in the treatment of RP. Doctors recommend annual eye examinations and evaluations for patients since there may be a tendency for affected patients to develop cataracts and/or retinal swelling.
Al-Salem et al. (1996) investigated the most common causes of blindness and the age of onset of these conditions among Jordanians of Irbid. The study group included 185 individuals who were blind according to the World Health Organization definition. Genetically determined causes made up 41% of the total causes for blindness in the patient group. In 57% of the subjects, blindness occurred in the first two decades of life. Retinitis pigmentosa was shown as the leading specific cause of blindness in the studied group (17.6%).
Al-Merjan et al. (2005) presented the causes and incidence rates of disorders leading to blindness and low vision in Kuwait, based on the data collected by the Visual Disability Committee in a 5-year period from 2000 to 2004. Of the 826,083 people (407,871 males) registered with blindness and low vision, 39% were below the age of 20-years, 32% were between the ages of 21and 40-years, while only about 10% were over 60-years of age. Retinitis pigmentosa was found to be leading cause of disability, with an overall incidence rate of 1.93 per 100,000 individuals. The incidence varied between males (2.69) and females (1.19).