What Is Retinitis Pigmentosa?

Overview

Retinitis pigmentosa (RP) is a genetic disorder that affects the cells in the retina, which is the light-sensitive tissue lining the back of the eye. It is a progressive condition, meaning it worsens over time, and it primarily affects the rods and cones, the two types of photoreceptor cells in the retina.¹

The rods are responsible for vision in low light conditions and peripheral vision, while the cones are responsible for color vision and central vision.² In people with RP, the cells in the retina, particularly the rods, degenerate and gradually die. This leads to a progressive loss of vision, typically starting with difficulty seeing at night or in dimly lit areas.

The characteristic feature of RP is the presence of pigment deposits in the retina, which can be seen during an eye examination. These deposits give the disorder its name. As the condition progresses, individuals may experience a narrowing of their visual field, known as tunnel vision, and eventually, their central vision may also be affected.

Causes of retinitis pigmentosa

Retinitis pigmentosa is primarily caused by genetic mutations that affect the functioning and maintenance of retinal cells. These mutations can be inherited from one or both parents, or they can occur spontaneously without a family history of the condition. The inheritance pattern can be autosomal dominant, autosomal recessive, or X-linked.^3,4

1. Autosomal Dominant RP: occurs when a person inherits a mutated gene from one affected parent. The mutated gene is dominant, meaning it only takes one copy of the gene to cause the condition. Examples of genes include RHO (rhodopsin) and RDS (peripherin)
2. Autosomal Recessive RP: occurs when a person inherits two copies of the mutated gene (one from each parent). The parents are usually unaffected carriers of the gene mutation
3. X-Linked RP: caused by mutations in genes located on the X chromosome. Since people assigned male at birth (AMAB) have only one X chromosome, they are more commonly affected by X-linked RP than people assigned female at birth (AFAB). The most common X-linked RP gene is RPGR

There are numerous genes associated with RP and the specific genetic cause can vary.⁵ Genetic testing and counseling are recommended for individuals with RP and their family members to determine the specific genetic cause and assess the risk of passing the condition to future generations.

Signs and symptoms of retinitis pigmentosa

The signs and symptoms of RP can vary across individuals, but they generally involve progressive vision loss and changes in visual function.⁶ Common signs and symptoms include:

1. Night blindness: Difficulty seeing in low-light conditions or at night is often one of the earliest symptoms of RP
2. Peripheral vision loss: RP typically causes a gradual loss of peripheral vision, leading to tunnel vision. The visual field becomes narrower which may result in difficulty seeing objects or people to the side or in the periphery
3. Decreased visual acuity: As the disease progresses, central vision can also be affected, resulting in a decline in visual acuity. This can impact tasks that require sharp or  detailed vision (e.g., reading, recognizing faces, watching television)
4. Light sensitivity: Increased sensitivity to bright lights, glare, or sunlight may cause discomfort, glare, or temporary vision loss
5. Presence of "bone spicules":⁷ During an eye examination, characteristic pigment deposits in the retina, known as "bone spicules," may be visible. These spicules are clumps of pigment that accumulate in the retinal cells
6. Impaired dark adaptation: Individuals with RP may have a slower adjustment to changes in lighting conditions, making it challenging to transition from bright to dim environments

Some people may experience a slow progression of symptoms over many years, while others may experience a rapid decline in vision. Regular eye examinations and consultations with an ophthalmologist or a retina specialist are crucial for monitoring and managing RP’s impact on vision.

Management and treatment for retinitis pigmentosa

While there is currently no cure for RP, several management strategies and treatments are available. These approaches aim to slow down the progression of the disease, alleviate symptoms, and enhance visual function. Common management and treatment options for RP include:⁸

1. Low-vision aids: Visual aids and assistive devices can help individuals with RP make the most of their remaining vision. Examples include magnifying glasses, telescopic lenses, and electronic devices that enlarge and enhance images
2. Orientation and mobility training: Specialized training programs can help individuals with RP navigate their environment more effectively. Techniques such as using a white cane, learning orientation skills, and mastering mobility strategies can improve safety and independence
3. Vitamin supplementation:⁹ Some studies suggest that high-dose vitamin A supplementation, under medical supervision, may slow down the progression of RP in certain individuals. However, this approach is not suitable for everyone and should be discussed with a doctor
4. Clinical trials and experimental treatments: There are ongoing research efforts exploring potential treatments for RP, including gene therapy and retinal implants

Diagnosis of retinitis pigmentosa

Diagnosis typically involves a comprehensive eye examination and may include additional tests to confirm the presence of the condition.¹⁰ Steps involved in the diagnosis of RP include:

1. Medical history and symptoms
2. Visual acuity testing
3. Visual field testing
4. Electroretinogram (ERG): An ERG is a specialized test that measures electrical responses of the retina to light stimulation. It assesses the function of the retinal cells, particularly the rods and cones. An abnormal ERG is often observed in individuals with RP.

The combination of these examinations and tests helps in diagnosing RP and distinguishing it from other retinal disorders. It is important to consult with an ophthalmologist or a retina specialist experienced in diagnosing and managing RP for an accurate assessment and diagnosis.

FAQs

Can retinitis pigmentosa be prevented?

There is currently no known way to prevent the development of RP because it is primarily caused by genetic mutations. However, there are some measures that can be taken to manage the condition and potentially slow its progression:¹¹

1. Vitamin A supplementation: High-dose vitamin A supplementation, under medical supervision, may slow down the progression of RP in specific individuals. However, vitamin A intake should be carefully monitored by a doctor, as high doses can have side effects. It is not a universal treatment and may not be suitable for everyone with RP
2. Protecting the eyes: Protecting the eyes and maintaining overall eye health is important. This includes wearing appropriate eye protection during activities that could pose a risk to the eyes, such as sports or certain occupations. Regular eye exams and prompt treatment of any eye conditions or infections are also recommended
3. Monitoring and management: Regular follow-ups with an ophthalmologist or a retina specialist are essential for monitoring the progression of RP and managing its impact on vision. They can provide guidance on low-vision aids, orientation, mobility training, and other interventions that can help individuals with RP optimize their remaining vision and maintain their quality of life

While these measures cannot prevent the development of RP, they can contribute to the overall management and well-being of individuals with the condition. Ongoing research is focused on finding treatments that may lead to better prevention or disease-modifying approaches for RP in the future.

How common is retinitis pigmentosa?

RP is a relatively rare condition, but its exact prevalence varies. The estimated prevalence is approximately 1 in 4,000 to 1 in 5,000 individuals worldwide.¹² However, these numbers are approximate and can vary based on different factors such as genetic background, geographical location, and study populations.

RP can affect anyone. However, the inheritance patterns of RP can influence its prevalence within specific families and populations. RP encompasses a group of inherited retinal disorders, and retinitis pigmentosa is often used as an umbrella term. Within this group, there are variations in disease severity, age of onset, and rate of progression, making it a complex condition with diverse clinical manifestations.

Since RP is a genetic disorder, individuals with a family history of the condition or those with symptoms suggestive of RP should seek a thorough professional evaluation for an accurate diagnosis and appropriate management.

Who is at risk of retinitis pigmentosa?

The risk of developing RP depends on the following:¹³ 

1. Family history: The most significant risk factor for RP. If one or both parents have RP or are carriers of RP gene mutations, there is an increased likelihood of their children inheriting the condition
2. Genetic mutations: Certain genetic mutations can increase the risk of developing RP. These mutations can be inherited from parents who are carriers of the mutated genes or can occur spontaneously as new mutations
3. Age and onset: While RP can affect individuals of all ages, certain types have an early onset during childhood, while others may manifest later in life. The age of onset can vary, and individuals who experience symptoms of night blindness, peripheral vision loss, or other visual disturbances should seek evaluation for RP

When should I see a doctor?

If you suspect RP or have a family history of RP, consult with a medical professional. Consider seeing a doctor if you have the following: 

• Symptoms of RP
• Family history 
• Concerns about visual changes

Early detection, accurate diagnosis, and appropriate management are crucial for RP and other retinal disorders. By seeking medical attention in a timely manner, you can receive proper care, access available treatments or interventions, and receive support and guidance tailored to your needs.

Summary

Retinitis pigmentosa is a group of inherited retinal disorders characterized by progressive vision loss. It primarily affects the cells in the retina responsible for vision in dim light (rods) and peripheral vision. RP is typically caused by genetic mutations that can be inherited or occur spontaneously. Common symptoms include night blindness, peripheral vision loss, and decreased visual acuity. Diagnosis involves a thorough eye examination, visual field testing, and genetic testing in some cases.