Overview
- Definition
- A heterogeneous group of inherited retinal dystrophies primarily affecting the rod photoreceptors, with progressive involvement of the cone photoreceptors and retinal pigment epithelium
The most common form of inherited blindness
- Symptoms
Nyctalopia
- Ring scotoma
Typically with superior field affected first
Symmetric involvement (except in X-linked female carriers)
Slow and relentless progression
Metamorphopsia (from macular edema)
Late stage: dyschromatopsia and vision loss
- Laterality
Bilateral
- Course
Slow and relentless progression
- Age of onset
First to second decade of life
- Gender/race
Not applicable
- Systemic association
Sensorineural hearing loss (30% of patients with retinitis pigmentosa [RP])
- A variety of syndromes are associated with RP:
Usher syndrome, Bardet-Biedl syndrome, Senior Loken syndrome, adult Refsum disease, etc.
Exam: Ocular
Anterior Segment
Posterior subcapsular cataract
Posterior Segment
Bone spicules
Waxy optic disc pallor
Arteriolar attenuation
Cystoid macular edema
Disc drusen
Vitreous cells
Exam: Systemic
Hearing loss
Imaging
- OCT
CME
Outer retinal atrophy
- ERG
Flat or “extinguished”
- Humphrey visual field (static automated perimetry) (HVF)
Ring scotoma, most notable on Goldmann kinetic perimetry
- Fundus autofluorescence
Perifoveal hyperautofluorescent ring with midperipheral hypoautofluorescent spicules
Laboratory and Radiographic Testing
- Genetic testing
Autosomal dominant RP: mild course with variable penetrance; mutations in rhodopsin and peripherin/RDS genes
Autosomal recessive RP: severe course with early onset
X-linked RP: very severe course with mutations in RPGR gene
Differential Diagnosis
Autoimmune retinopathy
Drug-induced retinal toxicity (e.g., thioridazine, chlorpromazine, chloroquine, hydroxychloroquine)
Pigmented paravenous retinochoroidal atrophy (PPRCA)
Rubella retinitis
Traumatic retinopathy
- Syndromic pigmentary retinopathy
Including: Bardet-Biedl syndrome, Usher syndrome, Leber’s congenital amaurosis, neuronal ceroid lipofuscinosis, Kearns-Sayre syndrome, Batten disease, Refsum disease, abetalipoproteinemia, and Senior Loken syndrome.
Congenital stationary night blindness (CSNB)
Choroideremia
Stargardt maculopathy
Bietti crystalline dystrophy
Vitamin A or zinc deficiency
Syphilis
Diffuse unilateral subacute neuroretinitis (DUSN)
Treatment
Referral to low vision specialist
Limitation of ultraviolet (UV) light exposure
Cataract extraction
For CME: topical or oral carbonic anhydrase inhibitors; intravitreal triamcinolone
- Dietary modification:
Vitamin A 15,000 IU daily
± docosahexaenoic acid (DHA) 1200 mg daily
± lutein 12–20 mg daily
Referral/Co-management
Low vision specialist
Genetic counseling