Fathimath Jila Shameem
Introduction
Retinitis pigmentosa (RP) is the most common group of hereditary retinal disorders, characterised by the progressive degeneration of photoreceptor cells in the retina, leading to gradual loss of vision (1). Rod dysfunction causes night blindness and peripheral visual loss, followed by cone involvement affecting central and colour vision (1).
RP can manifest in isolation (typical RP) or as part of a syndrome, such as Usher syndrome (hearing and vision loss) and Bardet-Biedel syndrome (1). Although no cure exists, advances in genetic testing and gene therapies are making early diagnosis increasingly important.
Epidemiology
Retinitis pigmentosa (RP) has a prevalence of approximately 1 in 3,000–4000. The age of onset and severity of symptoms depend on the inheritance pattern (1). Autosomal dominant RP is typically the least severe, with a later onset. Autosomal recessive RP is the most common form and usually presents with early onset, and X-linked recessive RP is the rarest and most severe form, also with early onset (3). The remaining cases are sporadic or simplex, meaning that only one person in the family has been affected, and there is no known family history or genetic cause(1). More than 150 genes have been identified as causing RP, with mutations in the rhodopsin gene being the most common cause (3).
Clinical Features
Night blindness (nyctalopia) is the earliest symptom and is often accompanied by difficulty adapting to dark environments(4). Progressive peripheral visual field loss commonly described as “tunnel vision” (4,5). Central vision loss generally manifests late in the disease; however, it may present earlier, depending on whether rod or cone involvement predominates(5).
Fundoscopic findings include mid-peripheral bone-spicule retinal pigmentation, arteriolar narrowing, and waxy optic disc pallor due to bilateral retinal degeneration (4,5). Macula may have atrophy or oedema(4). Visual field loss is progressive, initially as a ring scotoma, and progressing to severe visual field constriction (5). RP is often linked to myopia(4). Some complications of RP include posterior subcapsular cataract, open-angle glaucoma, and posterior vitreous detachment (1,3).
Investigations
Investigations for retinitis pigmentosa involve a thorough ophthalmologic evaluation using structural and functional tests (1). Visual field testing is performed to detect peripheral scotomata that progressively constrict, usually leaving a small central island of vision (4). Optical coherence tomography (OCT) is used to evaluate macular photoreceptor loss and the presence of macular oedema(3,4). Full-field electroretinography (ERG) shows an early decrease in scotopic rod responses, followed by diminished photopic cone responses. In later stages, responses become severely reduced or undetectable (1,3). Fundus autofluorescence (FAF) displays a hyperautofluorescent macular ring that delineates areas of damaged and unaffected retina. Electro-oculography (EOG) may be subnormal with an absent light rise(4). Genetic testing plays an important role in confirming the diagnosis, determining the inheritance pattern, identifying those who would benefit from gene-specific therapies, and providing genetic counselling for patients and their families (4).
Management
Management of retinitis pigmentosa emphasises on visual rehabilitation, symptomatic treatment, and development of novel disease-modifying treatments. Supportive care usually involves the use of low-vision aids, registering for visual impairment, mobility training, and getting help from social services as needed, as well as wearing UV-protective sunglasses (3,4). Annual ocular examination to assess visual acuity, visual field, monitor for treatable vision-threatening complications, and provide support as new treatment options emerge (3).
There remains controversy regarding nutritional supplements. Vitamin A palmitate is no longer recommended, whereas docosahexaenoic acid (DHA, 1200 mg/day) and lutein (12 mg/day) may be considered; however, evidence remains limited (2).
Complications related to RP are treated symptomatically. For instance, topical carbonic anhydrase inhibitors or oral acetazolamide for cystoid macular oedema, and cataract surgery for posterior subcapsular cataracts (2,3).
Gene therapy, stem cell therapy, retinal prostheses, and gene editing are among the new treatments under development (1–3). The gene treatment Voretigene Neparvovec (Luxturna) has been approved for retinitis pigmentosa caused by mutations in the RPE65 gene (1,5).
References
1. Retinitis Pigmentosa – StatPearls – NCBI Bookshelf [Internet]. [cited 2025 Nov 29]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK519518/
2. Alastair K.O. Denniston+ Philip I.Murray, editor. Oxford Handbook of Ophthalmology. Fourth Edition. Oxford University Press; 2018. 808 p.
3. Bowling B. Kanski’s Clinical Ophthalmology, Eighth Edition (2016). 2016.
4. Gervasio KA., Peck TJ., Fathy CA., Sivalingam MD., Friedberg MA., Rapuano CJ. The Wills eye manual : office and emergency room diagnosis and treatment of eye disease. Wolters Kluwer; 2022. 478 p.
5. Voretigene neparvovec (Luxturna) [Internet]. [cited 2025 Dec 18]. Available from: https://scottishmedicines.org.uk/medicines-advice/voretigene-neparvovec-luxturna-uo-reassessment-smc2641/