Retinitis Pigmentosa

Retinitis pigmentosa (RP) is a group of inherited retinal dystrophies in which the photoreceptor cells (primarily rods, then cones) progressively degenerate. It typically begins with night blindness and gradual loss of peripheral vision, eventually leading to tunnel vision. RP is the most common inherited retinal degeneration, affecting approximately 1 in 4,000 people worldwide.

Overview

The retina contains two types of photoreceptors: rods (responsible for peripheral and night vision) and cones (responsible for central and color vision). In RP, rods are affected first, which is why night blindness and peripheral vision loss are the earliest symptoms. As the disease progresses, cones are also lost, eventually affecting central vision.

RP is genetically diverse — over 100 different genes have been identified that can cause RP, with different inheritance patterns and rates of progression.

Symptoms

Early Symptoms

• Night blindness (nyctalopia) — difficulty seeing in dim light; often the first symptom, appearing in childhood or adolescence
• Slow dark adaptation — taking unusually long to adjust to darkness (movie theaters, nighttime driving)
• Difficulty navigating in low light

Progressive Symptoms

• Peripheral vision loss — gradual narrowing of the visual field
• "Tunnel vision" — seeing only through a narrow central area
• Difficulty with mobility — bumping into objects, trouble navigating unfamiliar environments
• Glare sensitivity — difficulty with bright lights
• Color vision changes — as cones are affected later

Late Symptoms

• Central vision loss — eventually, in many patients
• Legal blindness — many RP patients meet criteria by middle age
• Rate of progression varies widely — some patients maintain useful vision into their 60s-70s, while others lose significant vision by their 20s-30s

Inheritance Patterns

Pattern	Frequency	Key Features
Autosomal dominant	~15-25%	Mildest form; one affected parent; often slower progression
Autosomal recessive	~50-60%	Most common; parents are carriers; variable severity
X-linked	~5-15%	Affects males; most severe and earliest onset; carrier females may have mild changes
Simplex (no family history)	~40-50%	No known affected relatives; often autosomal recessive with carrier parents

Causes and Associated Conditions

Genetic Basis

RP is caused by mutations in genes essential for photoreceptor function and survival. The most common genes include:

• RHO (rhodopsin) — autosomal dominant
• USH2A — autosomal recessive, associated with Usher syndrome
• RPE65 — autosomal recessive, treatable with gene therapy (Luxturna)
• RPGR — X-linked

Usher Syndrome

• RP combined with sensorineural hearing loss
• The most common cause of combined deafness-blindness
• Three types with varying severity of hearing loss and RP progression
• All children diagnosed with sensorineural hearing loss should be screened for RP

Other Syndromic Forms

• Bardet-Biedl syndrome — RP + obesity + kidney issues + extra digits
• Kearns-Sayre syndrome — RP + progressive external ophthalmoplegia (mitochondrial)

Diagnosis

Key Tests

• Electroretinogram (ERG) — the gold standard; measures the electrical response of the retina to light; severely reduced or absent in RP, often before symptoms are obvious
• Visual field testing — documents the extent of peripheral vision loss and tracks progression
• Optical coherence tomography (OCT) — shows thinning of the outer retinal layers (photoreceptor layer) and can reveal cystoid macular edema
• Fundus examination — classic findings include bone-spicule pigment deposits, attenuated (narrowed) retinal blood vessels, and pale optic disc
• Fundus autofluorescence — shows a characteristic ring of hyperautofluorescence around the macula that narrows over time
• Genetic testing — increasingly important for identifying the specific gene mutation, which guides prognosis and potential eligibility for gene therapy

Treatment

Currently Available

Gene therapy — Luxturna (voretigene neparvovec):

• FDA-approved for RP caused by RPE65 mutations (a small subset)
• Delivers a working copy of the RPE65 gene via injection under the retina
• Can improve functional vision, especially in dim light
• Most effective when given before significant photoreceptor loss
• A landmark in ophthalmic gene therapy

Management of complications:

• Cystoid macular edema — treated with carbonic anhydrase inhibitors (dorzolamide drops or oral acetazolamide)
• Cataracts — cataract surgery when vision-limiting (posterior subcapsular cataracts are common in RP)
• Vitamin A supplementation — historically suggested to slow progression, but a 2024 AAO assessment found no clear evidence of effectiveness for any dietary supplement in RP; discuss with your ophthalmologist before taking (requires monitoring of liver function and lipids)

Emerging Therapies (Research Stage)

• Gene therapy for additional RP subtypes
• Retinal prostheses (bionic eyes) — Argus II was approved but discontinued; newer devices in development
• Optogenetics — making remaining retinal cells light-sensitive
• Stem cell therapy — replacing lost photoreceptors
• Neuroprotective agents — slowing photoreceptor death

Low Vision Rehabilitation

• Low vision aids — magnifiers, telescopic lenses, CCTV readers
• Orientation and mobility training — white cane, guide dog
• Assistive technology — screen readers, voice-activated devices, smartphone accessibility features
• Lighting optimization — maximizing useful vision in daily environments
• Support groups and counseling — adjusting to progressive vision loss

When to See a Doctor

Frequently Asked Questions

Will I go completely blind?

Not necessarily. RP progression varies greatly depending on the genetic type. Some patients retain useful central vision well into their 60s-70s. However, legal blindness (based on visual field loss) is common. Low vision rehabilitation helps maintain independence even with significant vision loss. For a broader perspective on this question, see Am I Going to Go Blind?

Is there a cure for retinitis pigmentosa?

There is no cure that restores lost vision, but gene therapy (Luxturna) can improve vision in patients with RPE65 mutations. Research into treatments for other RP subtypes is very active. Identifying your specific genetic mutation through testing is important for future treatment eligibility.

Should my family members be tested?

Yes. Genetic counseling and testing are recommended for family members of RP patients. This helps identify carriers, diagnose presymptomatic individuals, and provide family planning information.

Can anything slow the progression?

Vitamin A palmitate supplementation was historically suggested to slow progression, but a 2024 AAO assessment found no clear evidence of benefit from any dietary supplement in RP. Omega-3 fatty acids (DHA) have also been studied without clear evidence of benefit. Avoiding smoking and excessive light exposure is generally recommended. Genetic testing to identify eligibility for gene therapy trials is the most important step.

What is the role of genetic testing?

Genetic testing identifies the specific gene mutation causing RP, which helps predict progression, determine inheritance pattern, guide family counseling, and — critically — identify patients eligible for existing or upcoming gene therapy trials.

References