Retinitis Pigmentosa: An Optometrist’s Guide to OCT, FAF, ERG, Visual Fields, Genetics, and Referral
Retinitis pigmentosa is one of the most important inherited retinal diseases for primary eye-care providers to recognize.
Although the classic presentation is night blindness, peripheral field loss, bone-spicule pigmentation, vascular attenuation, and optic nerve pallor, modern RP management goes far beyond identifying pigment in the peripheral retina.
Today, the evaluation increasingly involves multimodal retinal imaging, functional testing, molecular diagnosis, management of treatable complications, low-vision intervention, and referral for inherited retinal disease evaluation and potential clinical trials or gene-specific therapy.
The National Eye Institute describes RP as a group of genetic retinal disorders characterized by progressive retinal-cell degeneration. Common early manifestations include nyctalopia and peripheral visual-field loss, while OCT, fundus autofluorescence, electroretinography, visual fields, and genetic testing can all contribute to diagnosis.
For optometrists, the practical question is not simply: “Does this patient have RP?”
It is: What phenotype does this patient have, how much functional retina remains, is there a treatable complication, could the condition be syndromic, has the patient received molecular testing, and where should they be referred?
What Exactly Is Retinitis Pigmentosa?
Classic retinitis pigmentosa is primarily a rod-cone dystrophy.
Rod photoreceptors generally become dysfunctional first, followed by progressive cone involvement.
This explains the typical clinical sequence:
Rod dysfunction → night blindness → midperipheral field loss → progressive peripheral constriction → cone involvement → reduced central acuity
However, RP is not one disease.
It represents a genetically heterogeneous group of inherited retinal degenerations caused by mutations in numerous genes involved in phototransduction, the visual cycle, ciliary function, retinal metabolism, photoreceptor structure, and retinal pigment epithelium function.
Different mutations can therefore produce dramatically different:
Ages of onset
Rates of progression
Fundus appearances
OCT patterns
Visual-field patterns
Systemic associations
Prognoses
Two patients carrying the diagnosis of “RP” may therefore have very different disease courses.
Modern management increasingly depends on determining the genotype as well as the phenotype.
Classic Clinical Presentation
A patient with typical RP often reports:
Difficulty seeing at night
Prolonged dark adaptation
Poor peripheral awareness
Bumping into objects
Difficulty navigating unfamiliar environments
Difficulty driving at night
Increasing glare or photophobia
Central acuity may remain surprisingly good despite substantial peripheral retinal degeneration.
A patient can therefore read 20/20 or 20/25 on the acuity chart while having significant functional visual disability.
This is one reason visual acuity alone is a poor marker of RP severity.
The Classic Fundus Triad
The classic ophthalmoscopic findings include:
1. Bone-Spicule Pigmentation
Pigment migrates into the retina and clusters around retinal vessels, producing the characteristic bone-spicule pattern.
These changes frequently begin in the midperiphery.
2. Retinal Arteriolar Attenuation
Retinal vessels may become progressively narrowed as retinal metabolic demand decreases.
3. Waxy Optic Disc Pallor
A pale or waxy appearance of the optic nerve can develop in more established disease.
Not every early RP patient has the classic triad.
In younger patients or early disease, the fundus can appear relatively normal despite significant rod dysfunction.
That is where OCT, FAF, visual-field testing, ERG, and genetic testing become particularly valuable.
The Optometrist's Initial RP Workup
A practical baseline examination should establish both retinal structure and visual function.
Consider documenting:
Best-corrected visual acuity
Refraction
Pupils
Color vision
Anterior-segment examination
IOP
Dilated retinal examination
Widefield retinal photography when available
Macular OCT
Fundus autofluorescence when available
Visual-field testing
Family pedigree
Age at symptom onset
Night-vision symptoms
Hearing history
Relevant systemic findings
If inherited retinal disease is suspected, the evaluation should ultimately include consideration of full-field ERG and genetic testing.
OCT in Retinitis Pigmentosa
OCT has become one of the most useful tools for following RP patients in everyday clinical practice.
The most important structure to examine is the outer retina.
Ellipsoid Zone
One of the most useful OCT biomarkers is the photoreceptor ellipsoid zone, or EZ.
In earlier disease, the central EZ may remain intact while progressively disappearing outside the fovea.
As RP advances, the preserved EZ band becomes progressively narrower.
Conceptually:
Normal retina → peripheral EZ disruption → progressive EZ constriction → small central island of preserved photoreceptors
The width of the preserved EZ provides an intuitive structural representation of remaining photoreceptor integrity.
Outer Nuclear Layer
Progressive photoreceptor loss results in thinning of the outer nuclear layer.
RPE Changes
Advanced disease may demonstrate significant disruption and atrophy of the outer retinal/RPE complex.
Do Not Miss Cystoid Macular Edema
One of the most clinically important reasons to obtain macular OCT in RP is to look for cystoid macular edema or cystic macular changes.
RP-associated CME can reduce central acuity even when the underlying photoreceptor degeneration remains relatively stable.
This matters because the retinal degeneration itself generally cannot be reversed, whereas CME may be treatable.
OCT may demonstrate:
Intraretinal cystic spaces
Increased central retinal thickness
Associated epiretinal membrane
Vitreomacular traction
Carbonic anhydrase inhibitors are commonly used for RP-associated CME. Topical dorzolamide or systemic acetazolamide may produce improvement in selected patients.
For an optometrist following an RP patient, a new reduction in central acuity should therefore trigger the question:
Did the RP suddenly accelerate, or has the patient developed a treatable macular complication?
Fundus Autofluorescence in RP
Fundus autofluorescence, or FAF, can reveal retinal abnormalities that are difficult to appreciate ophthalmoscopically.
A classic pattern is a hyperautofluorescent parafoveal ring surrounding a relatively preserved central retina.
The ring often represents a transition zone between relatively preserved photoreceptors centrally and more abnormal retina outside the ring.
Over time, that ring may constrict toward the fovea as degeneration progresses.
Outside the transition zone, areas of hypoautofluorescence may correspond to more advanced RPE and photoreceptor loss.
FAF can therefore be particularly useful for:
Establishing baseline disease extent
Demonstrating the transition zone
Monitoring progression
Comparing structure with OCT
Educating patients about the disease
A patient may understand disease progression much more easily when shown serial FAF images than when simply told that the retina has “changed.”
Visual Fields in Retinitis Pigmentosa
Visual-field testing is essential because RP is fundamentally a disease of progressive field loss. The classic progression begins with midperipheral sensitivity loss. A ring scotoma may develop, separating a central island from remaining far-peripheral vision. As the disease advances, the ring enlarges and peripheral islands disappear. Eventually, the patient may retain only a small central field. This represents the classic tunnel-vision pattern.
Choosing the Field Test
A standard 24-2 or 30-2 can document central function but may substantially underestimate peripheral disease.
Depending on the patient's stage and available equipment, consider:
Humphrey 30-2 for central field assessment
Wider-field static perimetry
Humphrey 60-4 when appropriate
Kinetic perimetry such as Goldmann or equivalent systems
Advanced patients may have an extremely small central island that requires careful fixation monitoring.
Serial testing should ideally use the same strategy whenever possible so changes can be compared meaningfully.
Electroretinography: When ERG Becomes Important
Full-field electroretinography assesses the electrical response of the retina to light stimulation.
In classic rod-cone RP:
Scotopic responses are generally affected earlier and more severely than photopic responses.
Early findings may include:
Reduced rod amplitudes
Reduced combined rod-cone responses
Delayed responses
As disease progresses:
Cone responses become increasingly abnormal
Overall amplitudes decline
Responses may eventually become essentially nondetectable
ERG can be particularly helpful when:
The diagnosis is uncertain
The fundus appears relatively normal
Symptoms appear disproportionate to visible retinal findings
Differentiating rod-cone from cone-rod disease
Evaluating pediatric patients
Distinguishing generalized retinal dysfunction from localized retinal disease
ERG findings should be interpreted alongside the clinical phenotype rather than in isolation.
Recent natural-history data also reinforce the importance of genotype: progression varies significantly among genetic subtypes of RP, and ERG parameters can provide prognostic information.
Genetic Testing Has Changed RP Management
Years ago, identifying the patient as having “retinitis pigmentosa” was often the end of the diagnostic process.
Today, it should increasingly be the beginning.
A molecular diagnosis can provide information about:
The causative gene
Inheritance pattern
Prognosis
Risk to family members
Syndromic associations
Eligibility for clinical trials
Eligibility for gene-specific treatment
Clinical genetic testing should always be interpreted in the context of the phenotype. A variant found on a laboratory report does not automatically prove causation, particularly when the finding is classified as a variant of uncertain significance.
When possible, patients with suspected inherited retinal disease should have access to an inherited retinal disease specialist and/or genetic counselor.
Family History Can Be Misleading
Do not rule out RP simply because the patient says:
“Nobody else in my family has it.”
Patients may have:
Autosomal recessive disease
De novo dominant mutations
X-linked disease
Unrecognized disease in relatives
Relatives who died before developing symptoms
Mildly affected relatives who were never diagnosed
A careful three-generation pedigree can still be useful, but absence of family history does not exclude inherited disease.
Important RP Inheritance Patterns
Autosomal Dominant RP
One affected parent may be present.
Disease severity can vary widely between genes and even among members of the same family.
Autosomal Recessive RP
Parents may be asymptomatic carriers.
There may be no other known affected relatives.
X-Linked RP
Often produces more severe disease in affected males.
Female carriers may demonstrate variable retinal findings depending on X-inactivation.
Mitochondrial and Other Complex Patterns
Some retinal dystrophies can have more complicated inheritance, another reason molecular testing can be valuable.
Think Beyond Nonsyndromic RP
One of the optometrist's most important responsibilities is determining whether retinal degeneration may be part of a systemic syndrome.
Ask about more than vision.
Hearing Loss: Think Usher Syndrome
RP accompanied by congenital or progressive hearing impairment should immediately raise concern for Usher syndrome.
Usher syndrome combines inherited retinal degeneration with hearing loss and, in some forms, vestibular dysfunction.
Ask about:
Hearing aids
Childhood hearing problems
Balance difficulties
Delayed speech development
Other Systemic Clues
Depending on the phenotype, systemic features can suggest disorders such as:
Bardet-Biedl syndrome
Alström syndrome
Refsum disease
Mitochondrial disorders
Other ciliopathies or metabolic disorders
Relevant historical clues can include:
Hearing abnormalities
Polydactyly
Obesity beginning in childhood
Renal disease
Diabetes
Neurologic symptoms
Developmental abnormalities
The retinal finding may occasionally be the clue that uncovers the systemic diagnosis.
Differential Diagnosis: Not Every Pigmentary Retinopathy Is RP
Several conditions can mimic retinitis pigmentosa.
The differential may include:
Cone-rod dystrophy
Leber congenital amaurosis
Choroideremia
Stargardt-associated retinal degeneration
Gyrate atrophy
Bietti crystalline dystrophy
Congenital stationary night blindness
Autoimmune retinopathy
Drug-related retinal toxicity
Previous inflammatory or infectious retinal disease
Severe retinal trauma
A particularly important distinction is between a progressive inherited rod-cone degeneration and a stationary disorder such as congenital stationary night blindness.
ERG, imaging, history, and genetics can help separate these entities.
Cataracts in RP
Posterior subcapsular cataracts are common in RP and may cause substantial glare and central visual degradation.
Patients may complain that their vision has suddenly become much worse even though retinal degeneration is progressing slowly.
Cataract surgery can improve the optical quality of the remaining retinal image, but counseling is essential.
The patient should understand that:
Removing the cataract does not restore retinal function that has already been lost.
Preoperative OCT is valuable for evaluating:
Ellipsoid-zone integrity
Macular atrophy
CME
Epiretinal membrane
These findings help establish realistic postoperative expectations.
Treatment of RP-Associated CME
For visually significant cystic macular changes, carbonic anhydrase inhibitors are commonly considered.
Options may include:
Topical dorzolamide
or
Oral acetazolamide
Systemic therapy has additional contraindications and potential adverse effects and generally requires appropriate medical consideration and monitoring.
Treatment response should be followed with both:
Visual acuity
OCT
An anatomically improved OCT does not always produce a proportional improvement in vision because underlying photoreceptor loss may limit visual potential.
What About Vitamin A?
This area deserves an important update.
Older literature suggested that approximately 15,000 IU/day of vitamin A palmitate could slow ERG decline in some RP patients.
However, a major genotype-informed reanalysis published in 2023 found no detectable generalized protective effect from vitamin A supplementation across RP, while the adverse association with vitamin E remained.
Therefore, routine high-dose vitamin A should not be presented as a universal treatment for RP.
High-dose vitamin A also carries potential systemic toxicity and can be inappropriate in certain inherited retinal disorders.
The practical approach is: Do not automatically prescribe high-dose vitamin A simply because a patient has RP.
Supplement decisions should be individualized in collaboration with an inherited-retinal-disease specialist when appropriate.
Gene Therapy and Luxturna
The most important proof of concept for inherited retinal disease treatment is voretigene neparvovec-rzyl—Luxturna®.
The FDA indication is specifically for patients with confirmed biallelic RPE65 mutation-associated retinal dystrophy who have viable retinal cells.
This distinction is extremely important.
Luxturna is not a general treatment for retinitis pigmentosa.
A patient must have:
1. An appropriate phenotype
2. Confirmed pathogenic variants involving both RPE65 alleles
3. Sufficient viable retinal tissue
4. Evaluation by an appropriate treatment center
The significance of Luxturna extends beyond the relatively small number of eligible patients. It demonstrated that replacing a defective retinal gene could produce meaningful functional improvement and helped establish the modern field of inherited retinal gene therapy.
Multiple additional gene-, cell-, and molecular-based strategies remain under investigation. The NEI continues to describe gene therapy, cell therapy, and pharmacologic approaches as active areas of RP research.
Low-Vision Rehabilitation Should Not Be an End-Stage Referral
Low-vision care is sometimes introduced only after severe visual disability has developed.
It can be useful much earlier.
Consider referral when the patient begins having difficulty with:
Reading
Mobility
Night travel
Driving
Occupational tasks
Computer use
School
Activities of daily living
Interventions may include:
Electronic magnification
Contrast enhancement
Screen readers
Smartphone accessibility
Orientation and mobility training
Occupational rehabilitation
Workplace accommodations
Preserving independence is a major component of RP management.
A Practical Optometric RP Follow-Up Protocol
The exact interval depends on phenotype, age, progression, complications, and specialist involvement.
For a relatively stable patient, a 6- to 12-month interval is often practical.
A follow-up might include:
Every Visit
Interval symptoms
Night vision
Functional peripheral vision
BCVA
Refraction when appropriate
Anterior-segment examination
IOP
Dilated retinal examination
Common Serial Testing
Macular OCT
Look for:
EZ progression
CME
ERM
Vitreomacular interface abnormalities
Retinal photography
Document pigmentation, vascular attenuation, and overall appearance.
FAF
Track the transition zone or hyperautofluorescent ring when available.
Visual field
Use the same strategy whenever possible for longitudinal comparison.
Periodically or When Indicated
Full-field ERG
Genetic testing/reanalysis
Color testing
Low-vision evaluation
Audiology/systemic testing when syndromic disease is suspected
When Should the Optometrist Refer?
Referral to an inherited retinal disease specialist is appropriate when:
RP is newly suspected
The diagnosis is uncertain
Genetic testing has not been performed
ERG is needed
Disease appears unusually aggressive
A syndromic condition is suspected
A potentially treatable genotype is possible
The patient is interested in clinical trials
Significant CME is present
Rapid unexplained central visual decline occurs
A retina specialist may also be appropriate for macular complications or other retinal pathology.
The optometrist can still remain an important part of the patient's long-term care.
The Optometrist's Role After Referral
Referral does not mean the patient disappears from primary eye care.
Optometrists are often ideally positioned to provide:
Annual or semiannual monitoring
Refraction
Cataract detection
OCT monitoring
CME detection
Low-vision referral
Occupational counseling
Family education
Coordination with retinal specialists
Detection of unrelated ocular disease
An RP patient can still develop glaucoma, dry eye disease, cataract, refractive changes, retinal tears, or other ocular conditions.
Not every future visual complaint should automatically be attributed to RP.
Clinical RP Decision Pathway
A practical clinical workflow is:
Night blindness / peripheral field loss
↓
Dilated examination
↓
Pigmentary retinal changes present?
↓
OCT + retinal imaging + FAF
↓
Visual field
↓
Classic rod-cone phenotype?
↓
Full-field ERG if needed to establish or characterize generalized retinal dysfunction
↓
Genetic testing + inherited retinal disease evaluation
↓
Determine syndromic vs nonsyndromic disease
↓
Look for treatable complications: CME, cataract, refractive error
↓
Establish structural and functional baseline
↓
Follow every 6–12 months depending on disease severity
↓
Re-refer or escalate for progression, macular complications, genetic-treatment eligibility, or clinical trials
Clinical Pearls for Optometrists
Pearl #1: 20/20 vision does not mean mild RP.
A patient may have excellent central acuity with severe peripheral visual-field restriction.
Pearl #2: OCT every RP patient.
You are not only monitoring degeneration—you are looking for treatable macular complications.
Pearl #3: Pay attention to the ellipsoid zone.
Its extent provides useful information regarding surviving central photoreceptor structure.
Pearl #4: FAF may show progression before the fundus photograph makes it obvious.
The hyperautofluorescent transition ring can be particularly useful for longitudinal documentation.
Pearl #5: A 24-2 alone does not characterize RP well.
RP frequently begins outside the central field being tested.
Pearl #6: Ask about hearing.
Hearing loss plus RP should immediately raise the possibility of Usher syndrome.
Pearl #7: No family history does not rule out inherited disease.
Recessive, X-linked, de novo, and previously unrecognized familial disease are all possible.
Pearl #8: Do not overinterpret a VUS.
Genotype must fit phenotype and inheritance.
Pearl #9: Do not automatically recommend high-dose vitamin A.
Current evidence does not support generalized vitamin A neuroprotection across RP genotypes.
Pearl #10: Genetic diagnosis matters more than ever.
Modern inherited retinal disease care is increasingly shifting from:
“This looks like RP.”
to:
“Which molecular retinal disease does this patient have?”
The Future of Retinitis Pigmentosa
The clinical vocabulary surrounding RP is gradually changing.
Historically, patients were classified largely by what doctors saw through the ophthalmoscope.
Today, RP is increasingly classified according to:
Phenotype + multimodal imaging + retinal function + genotype
This is important because patients who appear clinically similar may carry completely different mutations and have very different prognoses and potential treatment options.
As gene replacement, gene editing, RNA-based therapies, optogenetics, cell therapy, and neuroprotective approaches continue to develop, identifying the molecular cause of retinal degeneration will become increasingly important.
Comments