Retinitis Pigmentosa

The symptoms of retinitis pigmentosa can be seen right from childhood. Usually, the symptoms progressively get worse as the child grows up. The common symptoms of retinitis pigmentosa are:

• Tunnel vision: The person loses peripheral (side) vision and can only see things in a small confined space in the middle. This makes them prone to bumping into things as they move around, increasing the chances of injury.
• Night blindness: In night blindness, the person is unable to see during the night or in a room with dim and dark lighting like movie theatres. 
• Colour blindness: In colour blindness, the person loses the ability to distinguish between colours.
• Loss of central vision: Some people may also suffer from the loss of central vision.

In the later stages, the person can completely lose vision as the retinal damage is extensive.

Read more: Vision problems in babies

Retinitis pigmentosa (RT) is a genetic condition - it occurs due to a defect in one of the 50 genes that are responsible for the formation of photoreceptors (rods and the cones) in the eyes. Photoreceptors are the cells present in the retina which absorb the light and convert them into electrical signals so that they can be sent to the brain. RT can be passed on to future generations.

Scientists believe that the defect in the gene either stops the formation of photoreceptors or forms faulty receptors or produces a protein which is toxic for the photoreceptors. In all the cases, the retina deteriorates slowly, leading to vision loss.

There are some tests which can be done in order to diagnose retinitis pigmentosa (RP) in a person: 

• Ophthalmoscope: The doctor may use a tool called the ophthalmoscope to get a better look at the patient's retina. This can show the dark black or red spots present over the retina.
• Electroretinogram (ERG): In an ERG, the doctor checks the electrical activity of the photoreceptor cells. Reduced electrical activity is usually a sign of progressing damage of the photoreceptors.
• Visual field test: This test is done to determine the extent of vision loss and find the blind spots. The patient is instructed to follow a dot of light moving in a 180-degree half-circle in front of their head and to their sides. The person is asked to press a button whenever they see the light. This helps to determine the visual field and also the central vision of the person taking the test.
• Genetic test: Genetic testing can be helpful in diagnosing the disease and also the rate of progression of the disease.

There is no cure for retinitis pigmentosa yet. But there are therapies to slow down the process of degeneration. Intensive research for a cure through gene therapy and retinal prosthesis (replacing the damaged retina with a healthy one) is still in the very early stages.

So far, the therapeutic approach can only help in reducing the rate of progression of the disease. These therapies involve:

• Sunlight protection: People with RP are asked to wear dark glasses whenever they step outdoors.
• Vitamin therapy: Vitamin A and vitamin E have the potential to protect the photoreceptors and have antioxidant reactions which help in delaying the damage to the retina.
• Management of coinciding complications: Complications like cataract (clouding of the lens), macular oedema (build-up of fluid in the centre of the retina), refractive errors (myopia or nearsightedness and hypermetropia or farsightedness) and inflammatory reactions should be treated immediately to prevent the worsening of the vision.