Retinitis Pigmentosa

Retinitis pigmentosa is a group of inherited eye diseases that cause cells in the retina to gradually break down, leading to progressive vision loss that typically begins in childhood with difficulty seeing at night and eventually narrows the field of vision.

Table of contents

• What is Retinitis Pigmentosa?
• Symptoms and Progression
• Causes and Inheritance
• How Retinitis Pigmentosa is Diagnosed
• Treatment and Management Options
• Living with Retinitis Pigmentosa
• Current Research and Emerging Therapies
• Related Conditions

What is Retinitis Pigmentosa?

Retinitis pigmentosa (RP) is a group of rare eye diseases that affect the retina, which is the light-sensitive layer of tissue at the back of the eye^[1]. The retina contains special cells called photoreceptors that convert light into electrical signals, which the brain then interprets as images^[2]. In people with RP, these photoreceptor cells gradually break down and die over time, causing progressive vision loss^[1].

• Retina
• Photoreceptor cells (rods and cones)

RP is a genetic disease that people are born with, though symptoms usually don’t appear until childhood or adolescence^[1]. The condition affects approximately 1 in 3,500 to 1 in 4,000 people in the United States and Europe^[4]. An estimated 100,000 people in the United States have RP^[3].

The name “retinitis pigmentosa” is actually misleading. While “retinitis” means inflammation of the retina, RP doesn’t actually cause inflammation. A more accurate term would be “retinal dystrophy,” which means degeneration or wearing down of the retina^[2]. The “pigmentosa” part of the name refers to the buildup of pigment that occurs on the retina when photoreceptor cells break down^[2].

Symptoms and Progression

The symptoms of retinitis pigmentosa typically start in childhood and progress gradually over time. Because RP usually affects different types of photoreceptor cells at different stages, the symptoms follow a characteristic pattern^[1].

The most common early symptom is loss of night vision, a condition called night blindness^[1]. Parents may notice that children with RP have trouble moving around in the dark or adjusting when going from a dark room to a bright environment^[1]. This happens because RP typically affects rod cells first. Rod cells are photoreceptors that provide vision in low light and are concentrated in the outer portions of the retina^[3].

As the disease progresses, RP causes loss of side vision, also called peripheral vision^[1]. Over time, the field of vision narrows until only a small area of clear vision remains in the middle. This is often described as tunnel vision^[2]. Eventually, when cone cells (which detect colors and fine details in bright light) become affected, people with RP lose their central vision as well^[2].

Other symptoms of RP include^[1]:

• Sensitivity to bright light
• Loss of color vision
• Difficulty reading or doing close work
• Trouble recognizing approaching faces
• Difficulty detecting different colors

The progression of RP varies considerably from person to person. Some people lose their vision more quickly than others^[1]. Many people with RP are legally blind (having a corrected vision of 20/200 or worse in their best-seeing eye) by age 40^[3]. However, because the disease progresses slowly, symptoms may be so subtle at first that people don’t recognize the problem right away^[2].

Causes and Inheritance

Retinitis pigmentosa is caused by changes in genes that control cells in the retina^[1]. Researchers have identified close to 100 different gene variations that can cause RP^[2]. More than 60 genes are known to cause nonsyndromic retinitis pigmentosa (RP that occurs by itself without affecting other organs)^[4].

These genetic mutations disrupt the function of photoreceptor cells, causing them to gradually fail and die^[2]. Different gene variations can affect the retina through different pathways, which is why scientists consider retinitis pigmentosa to be a group of disorders rather than a single disease^[2]. This also explains why some people may have more severe vision loss or faster progression than others.

Most of the time, these changed genes are passed down from parents to children^[1]. RP can be inherited in different ways^[1]:

• Autosomal dominant: More than 20 genes are associated with this form. Mutations in the RHO gene are the most common cause of autosomal dominant retinitis pigmentosa, accounting for 20 to 30 percent of all cases^[4].
• Autosomal recessive: At least 35 genes have been associated with this form. The most common is USH2A; mutations in this gene are responsible for 10 to 15 percent of all cases^[4].
• X-linked: Changes in at least six genes can cause this form. Together, mutations in the RPGR and RP2 genes account for most cases^[4].

Less commonly, RP can be caused by some medicines, infections, or eye injuries, but these causes are not as common as genetic factors^[1]. In some cases, a person may have a spontaneous mutation rather than inheriting the condition from a parent^[2].

If you have RP, you can talk with your doctor or a specialist called a genetic counselor to learn more about your risk of passing RP to your children^[1].

How Retinitis Pigmentosa is Diagnosed

Eye doctors can check for RP as part of a comprehensive dilated eye exam. The exam is simple and painless. The doctor will give you eye drops to dilate (widen) your pupil and then check your eyes for RP and other eye problems^[1]. The exam includes a visual field test to check peripheral (side) vision^[1].

Other tests for RP include^[1]:

• Electroretinography (ERG): This test lets the eye doctor check how well your retina responds to light. It measures the electrical activity of photoreceptor cells^[1].
• Optical coherence tomography (OCT): This test uses light waves to take a detailed picture of your retina^[1].
• Fundus autofluorescence (FAF) imaging: In this test, the eye doctor uses blue light to take a picture of the retina^[1].
• Genetic testing: Your doctor may suggest a genetic test to learn more about the specific type of RP you have. This can tell you how your RP symptoms may change over time^[1].

Diagnosing RP can be challenging because symptoms may be subtle and progress slowly^[2]. While some people see their provider for testing in childhood, others don’t get a diagnosis until much later. Regular eye examinations are important, and many doctors recommend annual examinations that include visual field testing, with periodic electroretinography evaluations every five years^[8].

Treatment and Management Options

There is currently no cure for retinitis pigmentosa^[1]. However, several treatment options can help manage symptoms and may slow the progression of vision loss.

Low vision aids and rehabilitation (training) programs can help people with RP make the most of their remaining vision^[1]. Many devices and technologies are available to help with daily activities^[1].

Your eye doctor may discuss vitamins and supplements for RP. Vitamin A palmitate may help slow vision loss from the common forms of RP^[1]. Studies have concluded that high daily doses of vitamin A palmitate (15,000 units per day) may slow the progress of RP by about 2 percent per year^[8]. However, taking too much vitamin A can cause liver problems, so it’s important to talk with your doctor about the risks and benefits^[1]. Doctors recommend checking liver enzymes and vitamin A levels annually if taking this supplement^[8].

Other nutritional supplements that have been studied include^[8]:

• Beta-carotene (doses of 25,000 IU have been recommended)
• Docosahexaenoic acid (DHA), an omega-3 fatty acid and antioxidant
• Lutein and zeaxanthin, macular pigments that may protect the retina from oxidative damage

Gene therapy has been approved by the FDA for patients with confirmed biallelic (having both a paternal and maternal mutation) RPE65 mutation-associated retinal dystrophy^[8]. This represents an important advance for a specific subset of RP patients.

Perhaps most importantly, it is essential to help patients maximize the vision they do have through proper refraction and low-vision evaluation^[8]. Many devices are available to help patients with night vision difficulties, and most low-vision clinics are familiar with these tools^[8].

Living with Retinitis Pigmentosa

Living with retinitis pigmentosa requires adaptation and support, but many strategies can help people maintain independence and quality of life.

Practical strategies for managing daily life include^[11]:

• Having plenty of bright and even lighting in your home
• Learning how to navigate safely, with advice and support from professionals
• Using aids like magnifiers that help with seeing details
• Using color contrast to help see things around the home more clearly (for example, for light switches, buttons, and other everyday items)
• Making the most of everyday technology such as smartphones and tablets, which have apps and accessibility features for people with visual impairment

Your ophthalmologist may be able to refer you for a low vision assessment to explore the types of aids that will help you^[12]. Local social services can also provide support for keeping safe at home and when out and about^[12].

Many coping strategies can improve daily life for those living with RP. In one study published by the Journal of the American Optometric Association, the coping strategy most commonly used for dealing with stress from vision loss was humor. Study participants reported that laughter helped them come to terms with living with RP^[11]. Using social support and working with a team of specialists, such as occupational therapists and mobility specialists, can help people learn strategies for safely getting around and performing daily activities^[11].

For those who work, employers are legally required to make reasonable adjustments to support your needs. Practical changes could include ensuring a clear and tidy workplace, flexibility in working hours to enable travel in daylight, time off for medical appointments, and screen reading software^[12].

If you drive, you must tell the DVLA (in the UK) that you have retinitis pigmentosa. The law requires drivers to have a minimum field of vision. Since retinitis pigmentosa particularly affects peripheral vision, at some point your visual field may not meet the minimum standard. Usually, night vision will be affected first, meaning you may only be able to drive during the day^[12].

Current Research and Emerging Therapies

Significant efforts are being made in the development of new therapies for retinitis pigmentosa. Research advances offer hope for improved treatments in the future^[6].

Several emerging therapies are in development or clinical testing^[7]:

Gene Therapy: Beacon Therapeutics has reported vision improvements for patients receiving laru-zova, a gene therapy for X-linked retinitis pigmentosa (XLRP), in the Phase 2 DAWN clinical trial. The average improvement in low luminance visual acuity (the ability to read letters on an eye chart in dim light) for treated eyes was 16 letters or about 3 lines on an eye chart. The company has completed enrollment in a pivotal Phase 2/3 trial and expects to report results in 2026^[7].

Oral Antioxidant Therapy: Nacuity reported that NACA, an oral antioxidant, reduced photoreceptor loss by 50 percent in a Phase 2 clinical trial in Australia for people with Usher syndrome. The molecule is designed to slow vision loss by protecting retinal cells from oxidative stress^[7].

Stem Cell Therapy: A team of researchers has shown that CD34+ stem cells can be safely administered into retinitis pigmentosa patients’ eyes and may offer therapeutic benefits. The phase 1 trial also confirmed that these specialized cells can be readily isolated from the patient’s own bone marrow^[10].

Nanobody Treatment: Researchers have discovered a special antibody that may lead to a treatment for rhodopsin-associated autosomal dominant RP. The study focused on rhodopsin, a key light-sensing molecule in rod photoreceptor cells^[9].

Retinal Prosthesis: An artificial retina (retinal prosthesis) has been developed for people with very advanced disease and severe vision loss^[8].

Regular examinations can ensure that patients stay informed about clinical trials and new treatments as they become available^[8].

Related Conditions

Retinitis pigmentosa sometimes occurs as part of larger genetic syndromes that affect other organs and tissues in the body. These forms of the disease are described as syndromic^[4].

The most common form of syndromic retinitis pigmentosa is Usher syndrome, which is characterized by the combination of vision loss and hearing loss beginning early in life^[4]. Forms of RP and related diseases also include Leber congenital amaurosis and Bardet-Biedl syndrome, among others^[3].

Retinitis pigmentosa is also a feature of several other genetic syndromes, including Refsum disease and neuropathy, ataxia, and retinitis pigmentosa (NARP)^[4].

Some of the genes associated with retinitis pigmentosa are also associated with other eye diseases, including cone-rod dystrophy. Cone-rod dystrophy has signs and symptoms similar to those of retinitis pigmentosa. However, it is characterized by deterioration of the cones first, followed by the rods, so daylight and color vision are affected before night vision^[4].