retinitis pigmentosa 34

Retinitis Pigmentosa (RP): A Group of Inherited Eye Diseases

Retinitis pigmentosa (RP) is a group of inherited eye diseases that cause progressive vision loss. It affects the retina, the light-sensitive layer of tissue in the back of the eye.

• Causes: RP is caused by genetic variants that affect the production or function of proteins essential for the health and functioning of the retina.
• Symptoms:
  • Night blindness: Difficulty seeing at night due to degeneration of rod photoreceptors.
  • Peripheral vision loss: Decreasing peripheral vision (side and upper or lower visual field) as cone photoreceptors are affected.
  • Tunnel vision: As peripheral vision worsens, people may experience a constricted field of vision.
• Inheritance: RP can be inherited in an autosomal dominant, autosomal recessive, or X-linked pattern. It may also occur as part of a syndrome, such as Bassen-Kornzweig or Laurence-Moon syndromes.

Prevalence and Progression

RP is estimated to affect 1 in 4,000 people worldwide, with variable prevalence in different populations. The condition typically starts with involvement of the rod photoreceptors, followed by cone photoreceptors, and progresses gradually over time.

• Age of onset: Symptoms usually start in childhood or adolescence.
• Progression: RP is a progressive degeneration that can lead to complete blindness in some cases, although this is uncommon.

References

[1] (12) The name retinitis pigmentosa (RP), described initially as a clinical entity in 1853, was not attached to the disease until 1857. Considered by most to be a misnomer, the term retinitis persists today, even though inflammation plays only a small role in the natural progression of the disease.

[2] (14) Symptoms include trouble seeing at night and decreasing peripheral vision (side and upper or lower visual field). As peripheral vision worsens, people may experience "tunnel vision". Complete blindness is uncommon.

Common Signs and Symptoms of Retinitis Pigmentosa

Retinitis pigmentosa (RP) is a group of rare, genetic disorders that affect the retina's ability to respond to light. The symptoms of RP can vary from person to person, but there are some common signs and symptoms that are often experienced.

• Night Vision Problems: One of the earliest signs of RP is difficulty seeing in low-light conditions or at night. This is because the rods in the retina, which are responsible for peripheral and night vision, are affected first.
• Blind Spots in Peripheral Vision: As the disease progresses, people with RP may experience blind spots in their peripheral (side) vision. This can make it difficult to see objects or people out of the corner of your eye.
• Reduced Ability to See Objects in Shadows: People with RP may also have difficulty seeing objects that are partially hidden in shadows or dimly lit areas.
• Gradual Loss of Peripheral Vision: In advanced cases, RP can cause a gradual loss of peripheral vision, where people may experience "tunnel vision" and be unable to see anything outside of a narrow field of view.

These symptoms can develop gradually over time, often starting in childhood. If you or someone you know is experiencing these symptoms, it's essential to consult with an eye care professional for proper diagnosis and treatment.

References:

• [1] (6) Loss of night vision. Night blindness is when you cannot see anything in the dark.
• [2] (3) Reduced vision in poor lighting or dark conditions, or in shadows
• [4] (8) Other common signs include vitreous cells, depigmentation and atrophy of the RPE, posterior subcapsular cataracts, cystic macular lesions...

Diagnostic Tests for Retinitis Pigmentosa

Retinitis pigmentosa (RP) can be diagnosed through various tests that assess the retina's function and structure. Here are some of the diagnostic tests used to diagnose RP:

• Electroretinography (ERG): This test measures the electrical activity of the retina in response to light, helping to determine if there is any functional vision remaining [7][14].
• Optical Coherence Tomography (OCT): OCT takes detailed pictures of the retina, allowing doctors to visualize changes in the retinal structure and diagnose RP [5][9].
• Visual Field Testing: This test measures side vision and can detect blind spots that may be developing due to RP [4][11].
• Electrooculogram (EOG): EOG measures the standing potential between the front and back of the eye, which can help diagnose RP [4].
• Fundus Autofluorescence (FAF) Imaging: This test uses blue light to take a picture of the retina, helping doctors detect changes in the retinal pigment epithelium [2].

These tests are often used in combination to confirm the diagnosis of RP. Early detection and diagnosis can help manage the condition and slow down its progression.

References:

[1] Not provided (context 1) [2] Not provided (context 2) [3] Not provided (context 3) [4] Context 4, 8 [5] Context 5 [7] Context 7 [9] Context 9 [11] Context 11 [14] Context 14

Current Treatments for Retinitis Pigmentosa

While there is no cure for retinitis pigmentosa (RP), several treatments are available to manage the symptoms and slow down disease progression. Here are some of the current drug treatments:

• Luxturna (Voretigene Neparvovec): This is a gene therapy that targets the RPE65 gene, which is responsible for RP in some individuals. It has been approved by the FDA for the treatment of a small sub-population of people with RP [1].
• QR-421a: This is another gene therapy that targets the USH2A protein, which is involved in RP. It has shown promising results in clinical trials, but more research is needed to confirm its effectiveness [2].
• Oral Acetazolamide: This medication has been found to improve visual function in some individuals with RP, although the exact mechanism of action is not fully understood [3].

Emerging Treatments

Researchers are also exploring other potential treatments for RP, including:

• N-acetylcysteine (NAC): A Phase 3 clinical trial is currently underway at Johns Hopkins University to investigate the safety and efficacy of NAC in treating RP [4].
• Nanobodies: Researchers at UC Irvine have discovered a nanobody that may lead to treatment for RP, although more research is needed to confirm its effectiveness [5].

New Gene Therapy

Recently, new research has suggested that a novel gene therapy can improve vision in people who have lost nearly all sight to RP [6]. However, this study is still in its early stages, and more research is needed to confirm these findings.

It's essential to note that each individual with RP may respond differently to treatment, and the effectiveness of these treatments can vary. Consultation with a healthcare professional is necessary to determine the best course of treatment for each person.

References:

[1] Cross, N. (2022). Luxturna: A Gene Therapy for Retinitis Pigmentosa. [Context result 1]

[2] Wu, K. Y. (2023). QR-421a: A Novel Gene Therapy for Retinitis Pigmentosa. [Context result 4]

[3] May 16, 2024. Oral Acetazolamide Shows Encouraging Results in Treating RP. [Context result 5]

[4] Oct 7, 2024. Johns Hopkins University Launches Phase 3 Clinical Trial of NAC for RP. [Context result 7]

[5] Aug 29, 2023. UC Irvine Researchers Discover Nanobody That May Lead to Treatment for Retinitis Pigmentosa. [Context result 8]

[6] Oct 20, 2024. New Gene Therapy Shows Promise in Improving Vision in People with RP. [Context result 9]

Differential Diagnosis of Retinitis Pigmentosa

Retinitis pigmentosa (RP) can be challenging to diagnose, as it shares similar symptoms with other eye conditions. The differential diagnosis for RP involves ruling out other potential causes of vision loss and peripheral vision difficulties.

Conditions that can mimic RP:

• Leber's hereditary optic neuropathy: This is a rare genetic disorder that affects the optic nerve, leading to progressive vision loss.
• Stargardt disease: A juvenile form of macular degeneration that can cause central vision loss and night blindness.
• Usher syndrome: A genetic disorder that combines RP with hearing loss.
• Batten disease: A rare genetic disorder that causes progressive vision loss, hearing loss, and other systemic symptoms.

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