How to Diagnose Retinitis Pigmentosa

Retinitis pigmentosa is a general term for a group of genetic eye disorders characterized by a loss of peripheral vision and night vision. It is caused by defects in more than 100 genes that cause dystrophies to the retina and retinal epithelium.

Instructions

• 1

  Observe the onset of retinitis pigmentosa. The first symptoms are usually difficulty in performing tasks in low light conditions such as dusk or fog. Patients also may require a prolonged period to adjust between light and dark.

• 2

  Document subsequent symptoms of retinitis pigmentosa. Patients may experience tunnel vision although the loss of peripheral vision is frequently asymptomatic. Additional symptoms include bumping into furniture, difficulty with sports and seeing continual flashes of light.

• 3

  Conduct an ocular examination. Visual acuity can vary from 20/20 to near blindness late in the disease and most adult patients have posterior subcapsular cataracts. Other key findings are bone spicules, an optic nerve with a waxy pallor and retinal arteriolar attenuation.

• 4

  Perform laboratory studies to eliminate other diagnoses. Syphilis and toxoplasmosis are infectious agents that are commonly mistaken for retinitis pigmentosa. Additional diseases that can masquerade as retinitis pigmentosa include Abetalipoproteinemia, gyrate atrophy, Kearns-Sayre syndrome and Refsum disease.

• 5

  Take imaging tests to confirm a diagnosis of retinitis pigmentosa. An electroretinogram (ERG) is the most important test for retinitis pigmentosa because it can detect even mild photoreceptor impairment. An ERG can also measure the rod and cone function of the retina and is usually abnormal by early childhood. A severe loss of cone function is characteristic and is accompanied by a loss of rod function in varying degrees.