What Is Retinitis Pigmentosa?

Retinitis pigmentosa (RP) is a group of inherited eye diseases that can lead to significant vision loss. These diseases affect the retina, the tissue at the back of the eye, where photoreceptor cells called rods and cones gradually lose their function, leading to sight impairment over time.

Symptoms

RP typically begins in childhood, but the onset and progression of symptoms can vary widely. Most individuals with RP experience a significant loss of vision by early adulthood and are often legally blind by age 40.

Common symptoms include:

  • Night Blindness: Difficulty adjusting to darkness, such as when moving from bright sunlight into a dimly lit room.
  • Peripheral Vision Loss: Often results in “tunnel vision,” where side vision diminishes, requiring individuals to turn their heads to see objects around them.
  • Central Vision Loss: As RP progresses, it can affect the cones in the centre of the retina, impairing detailed work and colour vision.
  • Photophobia: Increased sensitivity to bright lights.
  • Photopsia: Seeing flashes of light that shimmer or blink.

Causes

RP is caused by mutations in over 60 different genes. These genetic mutations can be inherited in three primary ways:

  • Autosomal Recessive RP: Each parent carries one defective gene but shows no symptoms. If a child inherits two defective genes, they will develop RP. There’s a 25% chance for each child to be affected.
  • Autosomal Dominant RP: Only one defective gene from either parent is needed for the child to develop RP, with a 50% chance of passing it to each child.
  • X-linked RP: Mothers carry the defective gene and have a 50% chance of passing it to their children. Sons are more likely to be severely affected, while daughters usually have milder symptoms.

Diagnosis

Diagnosing RP involves several specialised tests:

  • Fundoscopy: Your doctor may dilate your pupils and examine your retinas with a slit-lamp and special lenses to look for characteristic dark spots.
  • Visual Field Test: This test measures peripheral vision by having the patient indicate when they see lights or objects in their side vision.
  • OCT: A specialised test that takes cross-section pictures of the retina.
  • Genetic Testing: Identifies the specific gene mutation causing RP.

If RP is diagnosed in one family member, it is recommended that all family members undergo screening.

Retinitis pigmentosa is an inherited eye disease that causes progressive vision loss by damaging the retina’s photoreceptor cells.

Retinitis pigmentosa (RP) causes gradual vision loss by damaging the retina’s photoreceptor cells, leading to eventual blindness.

Treatment

While there is no cure for RP, some treatments can help manage symptoms:

  • Acetazolamide: Reduces macular oedema (swelling in the retina) to improve vision.
  • Vitamin A Palmitate: High doses may slow the progression of RP, but due to potential toxicity, it is not routinely recommended.
  • Sunglasses: Protect eyes from harmful ultraviolet rays and reduce light sensitivity.
  • Retinal Implant: The Argus II implant can provide partial vision for individuals with late-stage RP. This device converts images into electrical pulses sent to the retina, helping some patients locate lights and windows and even read large letters. Unfortunately this is not yet available in South Africa.

Other emerging treatments include:

  • Cell Replacement Therapy: Replacing damaged retinal cells with healthy ones.
  • Gene Therapy: Introducing healthy genes into the retina to correct genetic defects.

Please note that these treatments are still in experimental phases and not yet available.

Additionally, various devices and rehabilitation services can help individuals with RP maximize their remaining vision and maintain independence.

Retinitis pigmentosa is a serious condition requiring prompt and ongoing medical attention. If you or a family member has been diagnosed with RP, consult your eye doctor for personalized care and management strategies.