A patient has had trouble seeing in the dark for years, and the fundus shows black pigment in the mid-periphery. Think of retinitis pigmentosa (RP). This article shows how to recognize RP on the fundus, fundus autofluorescence (FAF) and the electroretinogram (ERG), including eyes that have almost no pigment.

Think of retinitis pigmentosa when
  1. Night blindness came first, and the visual field has slowly narrowed.
  2. Both eyes show bone-spicule pigment in the mid-periphery.
  3. The retinal arteries are thin, and you cannot follow them out to the periphery.
  4. The rod response and the mixed response are reduced, or the ERG is flat.

What is retinitis pigmentosa?

Retinitis pigmentosa is an inherited degeneration of the photoreceptors. The rods are damaged first and the cones later, so it is a rod-cone dystrophy.

Rods handle vision in the dark, and they are damaged first over a wide area, so night blindness comes early. Then the visual field narrows from the mid-periphery, slowly, over years to decades. Visual acuity from RP itself falls late, when the central cones are lost, but cataract or CME can lower it earlier.

RP is the most common inherited retinal dystrophy, affecting about 1 in 3,000 to 5,000 people. Autosomal recessive inheritance is common, but RP can follow any pattern: autosomal dominant, X-linked or mitochondrial. Many patients have no affected relatives[1].

Findings

Fundus

The typical fundus shows three things in both eyes:

  1. Bone-spicule pigment (black, branching clumps) in the mid-periphery
  2. Mottled retinal pigment epithelium (RPE), which gives the fundus an uneven color
  3. Narrow retinal arteries

The optic disc may also look pale and waxy.

Fundus photograph of an eye with retinitis pigmentosa. Black, branching pigment clumps fill the mid-periphery on the right side of the image. The vessels are thin, and the macula still looks red.
Retinitis pigmentosa, mid stage: bone-spicule pigment and atrophy in the mid-periphery, thin retinal vessels, and a relatively spared macula. From Hamel 2006, CC BY 2.0.

In a normal fundus, you can follow the arterial branches far into the periphery. In RP, the arteries are so thin that you lose them on the way. If you cannot follow the arteries out, think of RP.

Syphilis can cause an RP-like fundus, so testing for it is sometimes worthwhile[1].

RP without pigment

Some patients have no typical bone spicules. This is called RP sine pigmento, and the fundus can look almost normal at first glance. In early RP there is no pigment yet, because the pigment appears only after the photoreceptors have degenerated.

Two findings still point to RP: the thin arteries, and the ring on FAF (below). A wide-field fundus photograph makes the thin arteries easier to see.

Do not rule out RP because there is no pigment. In every patient with night blindness, check the width of the retinal arteries.

Fundus autofluorescence

FAF shows dark patches in the mid-periphery, where the RPE has become atrophic. There is often a bright ring at the border between the atrophic periphery and the macula, which is still alive[1].

Wide-field fundus autofluorescence image of an eye with retinitis pigmentosa. Many dark round patches merge in the mid-periphery, and a bright area surrounds the macula.
Retinitis pigmentosa on wide-field FAF: dark patches in the mid-periphery and a bright ring around the macula.

ERG

Early in RP, the rod response and the mixed response (rods and cones together; dark-adapted 3.0 ERG) become smaller. The cone responses fall later. In advanced RP, the ERG is flat.

When the history and the fundus of both eyes are typical, you can make the diagnosis without an ERG. The ERG matters most when the fundus looks nearly normal, as in RP without pigment or in young relatives of a patient. The rod responses fall even before the retina looks abnormal[2].

The full-field ERG adds up the response of the whole retina. So it can be nearly flat while the macula still gives good visual acuity. Patients with an unrecordable ERG can often still read[3].

OCT

OCT shows thinning of the outer retina. The ellipsoid zone (EZ), the line made by the photoreceptors, fades from the edges of the scan toward the center.

This change is easy to miss unless you look for it. Even when the scan looks normal at a glance, follow the EZ from one edge of the scan to the other.

Complications and cautions

Cataract

Posterior subcapsular cataract is common. Cataract surgery helps, but plan it with care. The zonules can be weak. After surgery, the capsule tends to contract strongly, and the inflammation is often strong.

Macular edema and epiretinal membrane

Cystoid macular edema (CME) and epiretinal membrane are common. CME may respond to carbonic anhydrase inhibitors (CAIs): oral acetazolamide or topical drops[1]. Oral acetazolamide has more side effects, such as tingling of the hands and feet, fatigue and kidney stones, so topical drops are often tried first.

If CME does not improve, steroids are an option: eye drops, a sub-Tenon or intravitreal injection of triamcinolone, or a dexamethasone implant. Both CAIs and steroids can reduce the edema, but the gain in visual acuity is limited. Anti-VEGF injections thin the macula but have not improved acuity, so they are not recommended[4].

Sildenafil

Use sildenafil (Viagra) with caution in patients with RP[2]. In Japan, it is contraindicated.

 

Sildenafil blocks PDE5, but it also weakly blocks PDE6, the enzyme that works in phototransduction in the rods and cones. Some forms of RP are caused by mutations in a PDE6 gene. For this reason, patients with RP were excluded from the clinical trials of sildenafil.

Treatment

There is no treatment that stops RP. For RP caused by mutations in both copies of the RPE65 gene, gene therapy with voretigene neparvovec (Luxturna) is approved in the US (2017), the EU (2018) and Japan (2023)[4]. Genetic testing finds these patients, and it can also open the way to clinical trials.

Treat cataract and CME when they occur. Low-vision aids help. High-dose vitamin A has been tried, but there is no consensus that it helps[1].

Systemic diseases with RP

RP can be part of a systemic syndrome.

SyndromeLook for
UsherHearing loss
Bardet-BiedlExtra fingers, kidney disease
RefsumIchthyosis, neurological signs. Treated with diet
Bassen-KornzweigAtaxia, fat malabsorption. Treated with vitamins
Kearns-SayrePtosis, eye movement limits, heart problems

Kearns-Sayre syndrome shows a salt-and-pepper retina, most striking at the macula. Other associations include the mucopolysaccharidoses (Hunter, Hurler and Scheie), Batten disease and Cockayne syndrome[1].

Summary

  • RP is an inherited rod-cone dystrophy: night blindness first, then a slowly narrowing field, and loss of acuity late.
  • The fundus shows bone-spicule pigment, mottled RPE and thin arteries. If you cannot follow the arteries out to the periphery, think of RP.
  • Without pigment, look for thin arteries and a bright FAF ring around the macula, which is still alive.
  • The ERG shows reduced rod and mixed responses early and becomes flat later, sometimes while the patient can still read.
  • Watch for cataract with weak zonules and CME, and send patients for genetic testing.

Figure credits

Fundus photograph: Figure 2 from Hamel C. Retinitis pigmentosa. Orphanet J Rare Dis 2006;1:40, via Wikimedia Commons, licensed under CC BY 2.0. Unchanged.

Fundus autofluorescence: 53rd National Examination for Certified Orthoptists (Japan), afternoon session, question 30, booklet No. 3. Ministry of Health, Labour and Welfare. Cropped and rotated 90 degrees from the original, with the source added below the image.

References

[1] Salmon JF. Kanski’s Clinical Ophthalmology: A Systematic Approach. 10th ed. Elsevier; 2025. Chapter 15, Inherited retinal degenerations: retinitis pigmentosa.

[2] Yanoff M, Duker JS, eds. Ophthalmology. 5th ed. Elsevier; 2019. Chapter 6.14, Progressive and "stationary" inherited retinal degenerations; Chapter 6.45, Retinal toxicity of systemically administered drugs.

[3] Hamel C. Retinitis pigmentosa. Orphanet J Rare Dis. 2006;1:40. PMID 17032466.

[4] Japanese Ophthalmological Society. Guidelines for the management of retinitis pigmentosa 2026. Nippon Ganka Gakkai Zasshi. 2026;130(4):376-398. In Japanese.

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