Retinitis pigmentosa

This information is not a substitute for a consultation with a health professional and should not to be used as a means of diagnosing a condition.

Rod and cone photoreceptors

At the back of the eye, the retina is made up of rods and cones.

The central bit of the retina is made up of cones. They help us see the central bit of vision that we use for reading, looking at photographs and recognising faces.

The area of the retina around the central bit is made up of rods. The rods see the surrounding bits of vision and help us to walk around and not bump into things especially in the dark.

Rods and cone photoreceptors are good at seeing different things.

Rods are good at ‘seeing’:

• things that move
• in the dark
• in black and white
• in less detail

Cones are good at ‘seeing’:

• things that are still
• in daylight
• in colour
• in fine detail

All this information from the rods and cones in the retina, travels to a part of the brain which interprets the information, and lets us understand what we are seeing. All parts of the brain and eye need to be present and working for us to see normally.

What is retinitis pigmentosa?

Retinitis pigmentosa is the name given to a wide range of eye conditions. ‘Retinitis’ means disease or inflammation of the retina. ‘Pigmentosa’ refers to how the retina can look in this condition (the retina can often develop lots of small, dark specks of pigment).

Retinitis pigmentosa eye conditions are all linked by a problem with the rod and cone photoreceptors. The photoreceptors either work poorly from the day a child is born or else slowly stop working over a period of time. Usually the rods are affected more than the cones. Some retinitis pigmentosa conditions do not only affect the eye but may also affect the rest of a child’s body.

What are the causes of retinitis pigmentosa?

There are many different causes of retinitis pigmentosa. Sometimes nobody can say for sure why a child has retinitis pigmentosa. When eye doctors cannot figure out what might have caused it, we call it ‘idiopathic’.

Why might my child have retinitis pigmentosa?

Retinitis pigmentosa is caused by a misprint in the child’s genes. Genes contain the body’s ‘built-in’ plan to make sure all the parts of the body work correctly.

If a gene has a misprint, then a part of the body may not work correctly.

Retinitis pigmentosa is something that can just happen, or can be inherited by a person’s parents. There are many different ways a child can ‘inherit’ a condition.

How does retinitis pigmentosa affect the way a child sees?

Retinitis pigmentosa can affect different children in different ways.

Most young children who are born with rod and cone photoreceptors that do not work feel their vision to be ‘normal’. At first they assume that everyone else has vision the same as their own, as they have never known anything else but their own visual world. They do not realise that other people see things differently. However, most retinitis pigmentosa conditions become worse as the years pass.

Some older children may begin to notice that their vision is blurred around the edges and that their vision is especially poor in the dark. These children might mainly have a problem with their rod photoreceptors.

Some other children may notice that their central vision is becoming increasingly blurred and that most colours are not bright. These children may mainly have a problem with their cone photoreceptors.

Some other children may end up only seeing bright lights or the movement of large objects. These children may have problems with both cone and rod photoreceptors.

Sometimes in adulthood cataracts can develop. A cataract is when the normally clear lens of the eye becomes hazy. If the lens is not clear then not all the light can get into the eye and vision is often blurred. This can be treated by an operation. The hazy lens is removed and replaced by a clear plastic one.

Electroretinogram testing

There are  special tests that can be done to help the eye doctor decide what is wrong. These tests measure signals from the eyes when a child is shown a bright light. This test is called an electroretinogram (ERG).

1. Sticky patches are placed around the eyes.
2. The sticky patches are attached to wires that lead to a machine.
3. The machine records the electrical signals made by the eyes.
4. The record of the signals will help the doctors decide what the matter is.
5. If the signals are weak or absent then retinitis pigmentosa is more likely.

Is there any treatment for retinitis pigmentosa?

At present there is no good way to stop the sight loss in retinitis pigmentosa. But many things can be done to help children with this condition.

Further support

Many children with retinitis pigmentosa need early and specialist care from the local visual impairment support team. Even if a child has very poor vision many useful and practical things can be done to help.

This information is intended to describe most aspects of the condition but each child is different and there will always be exceptions.

Further reading

Read more about retinitis pigmentosa at Eyes on Genes.