Retinitis Pigmentosa

Retinitis pigmentosa is a genetically diverse group of inherited retinal dystrophies in which mutations in over 80 known genes (most commonly RHO, RPGR, USH2A, EYS) cause primary degeneration of rod photoreceptors followed by secondary cone loss. Inheritance can be autosomal dominant, autosomal recessive, X-linked, or mitochondrial, with onset typically in adolescence or early adulthood, although severity ranges from childhood-onset Leber congenital amaurosis to mild late-onset disease.

The classic clinical triad consists of nyctalopia (impaired dark adaptation), progressive concentric peripheral visual field constriction producing tunnel vision, and pigmentary retinal changes with bone-spicule deposits, attenuated retinal vessels, and waxy optic disc pallor on fundoscopy. Electroretinography shows reduced or extinguished rod responses early, with cone involvement later. OCT reveals outer-retinal atrophy and ellipsoid zone loss; fundus autofluorescence delineates the boundary of preserved retina.

Management is largely supportive but evolving. Voretigene neparvovec (Luxturna) gene therapy is approved for RPE65-associated retinal dystrophy, and multiple gene-replacement, antisense-oligonucleotide and stem-cell trials are underway. Vitamin A palmitate may slow progression in some forms; lutein and DHA supplementation are debated. Cataract surgery, low-vision rehabilitation, mobility training, and genetic counseling are essential. Progressive blindness usually develops by the fifth or sixth decade.