Retinitis pigmentosa: Unfolding its mystery

摘要

Retinitis pigmentosa affects 50,000-100,000 people in the United States and about 1.5 million people worldwide. Patients usually report impaired adaptation, night blindness, and loss of mid-peripheral visual field in adolescence. As the condition progresses, they lose far-peripheral visual field and eventually lose central vision as well. Some patients have become blind as early as age 30. The majority are legally blind by age 60, with a central visual field diameter of less than 20°. Findings on ophthalmoscopy include intraretinal pigment around the mid-peripheral retina, for which this condition is named. Histopathologic examinations of autopsy eyes with advanced stages have shown that loss of vision is due to degeneration of both rod and cone photoreceptor cells. Retinitis pigmentosa can be detected in early life by elec-troretinographic testing. Patients with early stages of this disease have electroretinograms (ERGs) that are reduced in amplitude with delays in their temporal aspects (Fig. 1). ERG amplitudes become smaller as the disease progresses. Abnormal ERGs have been detected in asymptomatic children in some cases a decade before diagnostic changes are seen on routine ocular examination. Individuals, age 6 and older, with normal ERGs and a family history of retinitis pigmentosa have not been observed to develop retinitis pigmentosa at a later time.