Retinitis pigmentosa

Retinitis pigmentosa (RP) typically presents with impaired night vision, problems with dark adaptation, decreased peripheral vision, and eventually decreased visual acuity.

The onset and pattern of degeneration vary, but most cases demonstrate atrophy of the retina and retinal pigment epithelium, bone spicule pigmentation, waxy pallor of the optic nerves, and retinal vascular attenuation.

Electroretinograms help confirm the diagnosis by demonstrating attenuated rod and cone signals. Other imaging and diagnostic tools include fundus autofluorescence, kinetic visual field testing, optical coherence tomography, and molecular genetic testing.

There is an approved gene replacement therapy that results in improved functional vision in patients with RPE65-mediated inherited retinal dystrophy, but no approved therapies for the other forms of RP. There are many other new therapeutics in development or clinical trials.

Although vitamin A supplementation was previously recommended for patients with RP based on a historic study, improved analysis of the study data has demonstrated that vitamin A is not beneficial.

RP is a term that encompasses a broad category of hereditary conditions of retinal degeneration that share a common pathophysiology.[1]Heckenlively JR. Retinitis pigmentosa. Philadelphia, PA: Lippincott; 1988.[2]Hartong DT, Berson EL, Dryja TP. Retinitis pigmentosa. Lancet. 2006 Nov 18;368(9549):1795-809. http://www.ncbi.nlm.nih.gov/pubmed/17113430?tool=bestpractice.com ​ Pathogenic variants in approximately 100 different genes result in symmetrical retinal degeneration due to loss of rod and cone photoreceptors in the retina. Inheritance can be autosomal dominant, autosomal recessive, X-linked, or, rarely, mitochondrial or digenic. RP most commonly presents with night blindness and progressive loss of peripheral vision.[3]Pruett RC. Retinitis pigmentosa: clinical observations and correlations. Trans Am Ophthalmol Soc. 1983;81:693-735. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1312466/pdf/taos00018-0717.pdf http://www.ncbi.nlm.nih.gov/pubmed/6676982?tool=bestpractice.com The timing, patterns, and course can be heterogeneous. Cone-rod and cone dystrophies are sometimes classified separately from RP, but increased genetic knowledge is revealing that these disorders are part of the RP spectrum.