Retinitis Pigmentosa

Diagnosis of RP begins with a thorough review of symptoms and medical history. Since those with RP are at a higher risk of other eye diseases including keratoconus, a thorough history and exam are imperative. Visual field testing can be used to assess peripheral vision loss. During this test, the individual covers one eye and uses the uncovered eye to stare straight ahead into a machine called a Goldmann perimeter, that projects a small bright light in various locations within their visual field. The machine then tracks which lights and/or areas the eye is able to detect and provides the amount of vision loss. Additionally, a fundoscopic examination with an ophthalmoscope, or optical coherence tomography (i.e., a non-invasive imaging test that provides cross-sectional images of the retina) may help better visualize the retina and optic nerve. In RP, there may be pallor of the optic nerve and/or pigment changes in the retina. Other diagnostic tests include full-field electroretinography, which is a gold-standard method that uses a device to measure the electrical response of the retina to light stimuli; and dark adaptometry, a method in which subjects are exposed to bright light stimuli, then placed in a dark room for thirty minutes, and the minimum intensity light that can be detected by the individual is subsequently recorded.  

Genetic testing should also be offered, especially in individuals with a known family history, which may reveal mutations in the RPE65 gene. Genetic testing can be obtained through several commercial comprehensive, next-generation sequencing retinal dystrophy panels. 

Currently, no cure for RP exists and treatment is therefore aimed at slowing the progression of the disease. Individuals should first be referred to a retina specialist. Nutritional supplementation with vitamin A, vitamin E, and omega-3 fatty acids has shown possible benefits for a limited group of individuals. However, the risks may outweigh the benefits, and thus, nutritional supplementation may not be generalizable to all individuals with RP.  

Gene therapy is an option for individuals with an identified genetic mutation. Voretigene neparvovec-rzyl is the first gene therapy that targets the RPE65 gene and is delivered by a single subretinal injection by an ophthalmologist. There are also several ongoing clinical trials on experimental therapies including retinal cell transplantation (i.e., retinal neurons harvested from mice and humans that are transplanted into the individual’s retina) and retinal prosthesis devices (i.e., devices that transduce light into electrical signals and bypass the diseased retinal layers).