Retinitis Pigmentosa


Retinitis Pigmentosa is a variety of inherited eye diseases, which affect the retina. Light detecting (photoreceptor) cells in the retina process light received into the eye into the image we see. If you have Retinitis Pigmentosathese light detecting cells break down, and eventually die. Therefore light cannot be processed into an image and you lose part of your vision.

Types & Causes of Retinitis Pigmentosa

The type of Retinitis Pigmentosais determined by the way in which it is inherited. When we say something is inherited this means that it is passed on through our genes. This can include many things from hair colour to diseases such as Retinitis Pigmentosa. It’s also worth noting that just because you carry the gene does not mean you are affected by the disease, just as two brown haired parents can have a blonde haired child.

If both parents carry the Retinitis Pigmentosagene but are unaffected by the disease then this is referred to as autosomal recessive Retinitis Pigmentosa. If both parents carry the gene there is a ¼ chance that the child will actually get Retinitis Pigmentosa.  If one parent has the defective Retinitis Pigmentosagene then the chances of the child getting the gene are one in every two.  This is called autosomal dominant Retinitis Pigmentosa.

X linked Retinitis Pigmentosais slightly more complicated.  Here women carry the disease and each child has a 50:50 chance of inheriting the disease.  Daughters who inherit the disease are simply carriers and continue to pass on the same chance to their children, without suffering from the disease. However men who inherit the disease simply suffer from it and will not pass it on.   Because only women carry this form of the disease it can be passed down several generations of a family before a male suffers from the disease. This often makes X linked Retinitis Pigmentosahard to identify.

Because Retinitis Pigmentosa is an inherited disease it cannot be spread from person to person nor can it be caused by illness or injury. It is passed on through parents to children in the ways described above. Though currently half of Retinitis Pigmentosa cases are of unknown origin and cannot be traced via inherited links. Scientists are unsure and have differing opinions as to how these cases occur.

Symptoms of Retinitis Pigmentosa

Although Retinitis Pigmentosa is inherited, symptoms can start as early as 10 years old or as late as 30 years old. Because people are affected in different ways by Retinitis Pigmentosa there are a variety of symptoms depending on how the cells deteriorate.

Symptoms include:

  • This is the most common symptom. For example, a dimly lit room or outside at dusk.
  • You may lose periphery vision, so that your vision is limited, akin to looking down a straw.  This is known as tunnel vision.
  • In some cases the central vision is lost first, so the only sight is a donut shaped.

Diagnosing Retinitis Pigmentosa

If you lose central vision then you are no longer able to read a test card, in a typical eye test.  Further tests would have to be carried out to diagnose Retinitis Pigmentosa and not just a loss of sight, which can be caused by many other factors. Similarly, if you lose peripheral vision, you would be able to read a test card for a long time before your central vision became affected.

Retinitis Pigmentosa can be diagnosed using specific eye tests. The most comprehensive of these tests being the Electroretinogram (ERG) test. When a person has Retinitis Pigmentosa their photoreceptor cells degenerate. In the ERG test electrical currents produced by the retina are recorded, the speed and the intensity of these cells reduce as the Retinitis Pigmentosa progresses.

The main eye test used to diagnose Retinitis Pigmentosa that affects the central vision is called the acuity test. The acuity test measures how accurate your central vision is, by varying the distances from a test card and the lighting conditions. In a similar way the visual field test uses a special machine to measure the range of vision that you have.

Because the rod cells degenerate when a person has Retinitis Pigmentosa, your optometrist may use a dark adaptation test and adjust the lighting conditions to understand how the rod cells are functioning.

Treatment for Retinitis Pigmentosa

Currently there is not a treatment to cure or stop the progress of Retinitis Pigmentosa. However many research institutes across the world have identified some of the genes, which cause Retinitis Pigmentosa.

There is the hope that corrective genes may be introduced to stop Retinitis Pigmentosa developing. Gene therapy has also been explored so that if a parent knows they have a defective gene they can stop this from being passed on to their offspring.


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