Retinitis pigmentosa

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Retinitis pigmentosa is a group of eye disorders that are characterized by vision loss that worsens over time. These disorders affect the retina, which is the layer of light-sensitive tissue at the back of the eye. In people with retinitis pigmentosa, vision loss occurs as the specialized light receptor cells (photoreceptors) of the retina gradually deteriorate. The vision loss typically affects both eyes (bilateral), but the age at which symptoms appear and the course of the disease can vary among affected individuals.

The first sign of retinitis pigmentosa is usually a loss of night vision, which may occur in childhood or adolescence. Problems with night vision can make it difficult to move around in low light. Later, the disease causes blind spots to develop at the edges of the visual field (peripheral vision). Over time, these blind spots increase in size until they merge to produce tunnel vision. Eventually, vision in the center of the visual field is impaired. This affects detailed tasks such as reading, driving, and recognizing faces. Most people with retinitis pigmentosa become legally blind in adulthood.

When retinitis pigmentosa occurs on its own, without signs and symptoms in other parts of the body, it is called nonsyndromic retinitis pigmentosa. Researchers have identified several major types of nonsyndromic retinitis pigmentosa, which are usually distinguished by their pattern of genetic inheritance.

In 20 to 30 percent of cases, retinitis pigmentosa occurs as part of a syndrome that affects other organs and tissues in the body. These forms of retinitis pigmentosa are called syndromic retinitis pigmentosa. The most common form of syndromic retinitis pigmentosa is Usher syndrome, which is characterized by retinitis pigmentosa combined with hearing loss that begins early in life.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Genetic changes that cause disease are called pathogenic variants. Pathogenic variants in more than 130 genes are known to cause retinitis pigmentosa. Variants in the RHO, USH2A, and RPGR genes are among the most common causes of retinitis pigmentosa.

Many of the genes that are associated with retinitis pigmentosa play essential roles in the structure, function, or maintenance of the photoreceptors. The retina contains two types of photoreceptors: rods and cones. Rods are responsible for vision in low light, while cones provide vision in bright light, including color vision.

The pathogenic variants that are responsible for retinitis pigmentosa lead to a gradual loss of rods and cones in the retina. The increase in cell death causes the characteristic pattern of vision loss that occurs in people with retinitis pigmentosa. Rods typically break down before cones, which is why night vision impairment is usually the first sign of the disorder. Daytime vision and color vision are disrupted later, as both rods and cones are lost.

When retinitis pigmentosa occurs as part of a syndrome, it is caused by variants in the gene that are associated with that syndrome.

A genetic cause is found in 50 to 80 percent of people with retinitis pigmentosa. A genetic cause is more likely to be found in affected individuals who have a family history of retinitis pigmentosa. Some people with retinitis pigmentosa do not have an identified variant in any of the genes known to be associated with this condition. The cause of the condition in these individuals is unknown.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

Retinitis pigmentosa can have different inheritance patterns depending on the specific gene involved.

Retinitis pigmentosa often has an autosomal dominant inheritance pattern, which means one copy of an altered gene in each cell is sufficient to cause the disorder. Most people with autosomal dominant retinitis pigmentosa have an affected parent. Pathogenic variants in the RHO gene are the most common cause of autosomal dominant retinitis pigmentosa.

Retinitis pigmentosa can also have an autosomal recessive pattern of inheritance, which means both copies of a gene in each cell must have a pathogenic variant to cause the disorder. The parents of an individual with an autosomal recessive condition each carry one copy of the altered gene, but they typically do not show signs and symptoms of the condition. Pathogenic variants in the USH2A gene are the most common cause of autosomal recessive retinitis pigmentosa.

Less commonly, retinitis pigmentosa can be inherited in an X-linked pattern. The genes associated with X-linked retinitis pigmentosa are located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is typically sufficient to cause the condition. This is not always true for females (who have two X chromosomes). However, at least 20 percent of females who carry only one altered copy of a gene associated with X-linked retinitis pigmentosa develop retinal degeneration and the associated vision loss. Variants in the RPGR gene are the most common cause of X-linked retinitis pigmentosa.

Rarely, retinitis pigmentosa is inherited in a digenic pattern, which means that a variant must be present in two different genes to cause the disorder.

In 40 to 50 percent of all cases of nonsyndromic retinitis pigmentosa, only one person in a family is affected. In these individuals, the disorder is described as simplex. It can be difficult to determine the inheritance pattern of simplex cases because affected individuals may have no affected relatives or may be unaware of other family members with the disease. Although simplex cases can be caused by a new (de novo) gene variant that is not present in other family members, they are typically the result of autosomal recessive inheritance.

When retinitis pigmentosa occurs as part of a syndrome, it follows the inheritance pattern of that syndrome.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Retinitis pigmentosa is the most common inherited disease of the retina (retinopathy). It is estimated to affect 1 in 3,500 to 1 in 4,000 people in the United States and Europe.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Abnormal electroretinogram · Very frequent (99-80%)

Any abnormality of the electrical responses of various cell types in the retina as measured by electroretinography.

Abnormal retinal vascular morphology · Very frequent (99-80%)

A structural abnormality of retinal vasculature.

Abnormality of retinal pigmentation · Very frequent (99-80%)

Any deviation from the normal pigmentation of the retina.

Blindness · Very frequent (99-80%)

Blindness is the condition of lacking visual perception defined as a profound reduction in visual perception. On the 6m visual acuity scale, blindness is defined as less than 3/60. On the 20ft visual acuity scale, blindness is defined as less than 20/400. On the decimal visual acuity scale, blindness is defined as less than 0.05. Blindness is typically characterized by a visual field of no greater than 10 degrees in radius around central fixation.

Bone spicule pigmentation of the retina · Very frequent (99-80%)

Pigment migration into the retina in a bone-spicule configuration (resembling the nucleated cells within the lacuna of bone).

Conductive hearing impairment · Very frequent (99-80%)

An abnormality of vibrational conductance of sound to the inner ear leading to impairment of sensory perception of sound.

Nystagmus · Very frequent (99-80%)

Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms.

Optic atrophy · Very frequent (99-80%)

Atrophy of the optic nerve. Optic atrophy results from the death of the retinal ganglion cell axons that comprise the optic nerve and manifesting as a pale optic nerve on fundoscopy.

Other findings in the same source

From: Orphanet

Additional reported features include Photophobia (Very frequent (99-80%)); Retinal degeneration (Very frequent (99-80%)); Sensorineural hearing impairment (Very frequent (99-80%)); Visual impairment (Very frequent (99-80%)); Progressive night blindness (Very frequent (99-80%)); Abnormal full-field electroretinogram (Frequent (79-30%)); Attenuation of retinal blood vessels (Frequent (79-30%)); Cystoid macular edema (Frequent (79-30%)); Glaucoma (Frequent (79-30%)); Hyperinsulinemia (Frequent (79-30%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Retinitis pigmentosa is Ophthalmology, with a ophthalmologist as the relevant type of clinician. Ophthalmologist; paediatric services for children as appropriate.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Which part of the eye or visual pathway is affected?
• What change in vision requires immediate contact with the eye service?
• What are the aims and alternatives of any proposed eye treatment?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Retinitis pigmentosa. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.