is the name given more than a century ago to a condition in which pigmented spots were observed at the base of the eye using ophthalmoscopy.
It was originally believed to be an inflammatory disease, but during the 20th century it was discovered that the condition is genetic, caused by gene defects. It also became clear that RP is one of the hereditary eye diseases most likely to lead to blindness with age.
There are multiple gene mutations that can cause the disease, but only a small number (fewer than ten) have been fully identified to date.
Retinitis pigmentosa is a rare disease, with a prevalence of approximately 1 in 2,700 people in the United States.
The retina contains two types of light-sensitive cells: rods and cones. Rods are located mainly in the outer retina and are activated in low-light conditions.
Most forms of retinitis pigmentosa primarily affect rods first, leading to loss of night vision and peripheral (side) vision.
Cones are mainly located in the central retina and are responsible for color vision and fine detail. When cones are affected, patients gradually lose central vision and color perception.
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Symptoms of Retinitis Pigmentosa
Early symptoms usually appear in early childhood. The main symptoms include:
1. Night blindness (loss of night vision)
Difficulty seeing in low light may begin as early as age five. Night blindness is a universal and defining symptom of the disease.
Patients cannot see in the dark, although daytime vision may remain normal initially. Over time, adaptation to darkness becomes slower.
People may bump into objects, have difficulty driving at night, or struggle to see in dark environments such as cinemas.
2. Gradual loss of peripheral vision
This is often described as “tunnel vision.” Patients may bump into objects because they cannot see things in their side vision.
3. Loss of central vision
Some patients also develop central vision problems, making detailed tasks such as reading or sewing difficult.
Loss of visual field is very common (reported in about 94% of patients), while central vision loss varies widely.
Some individuals retain central vision until older age, while others lose it as early as their 30s.
Retinal changes vary with disease progression. Early stages may show no obvious signs in the first decade of life. In the second decade, pale spots appear in the retina along with dark pigment deposits. Later, retinal degeneration occurs with characteristic bone-spicule pigmentation.
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Causes and Risk Factors of Retinitis Pigmentosa
More than 60 genes are associated with this disease. It can be inherited in several patterns:
1. Autosomal recessive inheritance
Both parents carry one copy of the mutated gene without symptoms. If a child inherits both copies, the disease appears.
Each child has a 25% chance of being affected.
2. Autosomal dominant inheritance
Only one copy of the mutated gene is needed for the disease to appear.
Each child has a 50% chance of inheriting the condition.
3. X-linked inheritance
The gene is carried on the X chromosome. Mothers may be healthy carriers but pass the gene to their sons. Affected males usually develop severe symptoms.
Fathers do not pass the disease to their sons in this form.
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Complications of Retinitis Pigmentosa
•    Early development of cataracts
•    Swelling of the retina (macular edema)
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Diagnosis of Retinitis Pigmentosa
Doctors may diagnose the condition through eye examination and the following tests:
1. Ophthalmoscopy
Eye drops are used to dilate the pupil, allowing examination of the retina. Characteristic dark pigment spots may be visible.
2. Visual field test
The patient focuses on a central point while responding to lights appearing in peripheral vision. This creates a map of visual field loss.
3. Electroretinography (ERG)
Electrodes or special lenses measure how the retina responds to flashes of light.
4. Genetic testing
A DNA sample is analyzed to identify the specific genetic type of retinitis pigmentosa.
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Treatment of Retinitis Pigmentosa
There is currently no definitive cure. Past experimental treatments (such as early surgical implants) have not proven effective.
1. Treatments that may slow progression
•    Acetazolamide: may reduce swelling in the central retina (macular edema) and improve vision.
•    Vitamin A therapy: high doses may slow progression, but excessive intake can be toxic and must be medically supervised.
•    Sunglasses: reduce light sensitivity and protect the eyes from UV exposure.
•    Retinal implants: may provide partial vision in advanced stages.
2. Treatments under research
Current research focuses on:
•    Gene replacement therapy (introducing healthy gene copies)
•    Stem cell transplantation into the retina
•    Electronic retinal implants that convert light into signals for the optic nerve
These approaches show promising potential for future treatment.
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Prevention of Retinitis Pigmentosa
Genetic counseling and genetic testing can help identify whether a child is at risk of developing the disease.