Retinitis pigmentosa

What is retinitis pigmentosa?

Retinitis pigmentosa is the term used for a group of closely related inherited eye conditions that affect the retina, the specialised light-sensitive tissue at the back of the eye. A person’s sight loss usually happens gradually, over many years – and sometimes eventually leads to registered blindness.

Retinis pigmentosa is the most common inherited eye condition, affecting around one in 4,000 people in the UK.

Although most people with the condition will only have sight loss, less commonly it can occur as part of a broader inherited syndrome that affects other parts of the body. Examples include Usher, Bardet-Biedl (BBS) and Alström syndromes and Refsum disease, which all cause RP-like sight loss along with other health conditions.

What causes retinitis pigmentosa?

Retinitis pigmentosa is caused by the gradual decline and loss of light-sensing cells called photoreceptors in the retina, which are vital for healthy eyesight.

Scientists have so far identified that faults in more than 60 different genes can cause RP – but there are many more still to discover. Examples include genes known as RHO, USH2A and RPCR. These are passed down through families in different patterns, which can skip a generation depending on the exact genetic cause.

Scientists are studying the function of the genes responsible for retinitis pigmentosa to find out more about the biology behind the condition and uncover potential new treatment strategies. Faults in any of these genes cause photoreceptors to stop working and die over time, leading to sight loss in patients. They each contain the instructions for making proteins that are important for maintaining the correct structure and function of these important retinal cells.

What are the signs and symptoms of retinitis pigmentosa?

Symptoms of retinitis pigmentosa tend to appear during childhood or early adulthood – but in rare cases they can start much later. However, it is difficult to predict both the severity and how quickly an individual’s sight loss will progress – as this varies widely from person to person depending on the exact genetic cause of their condition.

One of the earliest symptoms of RP is ‘night blindness’ which can affect a person’s ability to see in dim light. They will often start to have problems with their side (or peripheral) sight, which may cause them to start bumping into things like doors or furniture. As the condition progresses, they will gradually develop ‘tunnel vision’ – but many people will keep their detailed, straight-ahead (central) sight into their 50s or older.

However, people with advanced stages of retinitis pigmentosa will often also develop problems with their central vision and this can severely affect their ability to carry out everyday activities like reading. They may also find it more challenging to deal with glare from bright lights and sunlight and in adapting to changes in light levels. Some people will eventually develop complete blindness.

How is retinitis pigmentosa diagnosed?

An optometrist or ophthalmologist (hospital eye doctor) will use a special instrument to examine a person’s retina to look for the presence of abnormal patches of dark pigment, which is a common sign of retinitis pigmentosa. Further detailed imaging tests will enable them to look at the fine structure of the retina for more subtle signs of damage.

They will usually also carry out a field of vision test to assess if a person has any changes to their peripheral sight. They may also perform a test known as electroretinogram (ERG) to measure the electrical activity of the retina, which is usually decreased in patients with retinitis pigmentosa due to the decline of their photoreceptor cells.

Genetic testing can help to confirm a diagnosis of retinitis pigmentosa. This can also provide information about the inheritance pattern of the condition and risks to other family members.

How is retinitis pigmentosa treated?

Unfortunately, there is currently no known cure or effective treatments that can stop the progression of retinitis pigmentosa. However, the development of gene replacement therapies and other potential new treatments are offering hope for patients for the future.

Some people with retinitis pigmentosa will develop cataracts – and in these cases, cataract surgery may help improve their sight.

What research is underway into retinitis pigmentosa?

There is much ongoing research into finding the remaining genes that cause retinitis pigmentosa, how genetic changes cause damage to the photoreceptors and developing new treatments that can slow down or reverse sight loss.

What can I do?

A person with advanced retinitis pigmentosa may benefit from a low vision assessment to evaluate their needs – such as low-vision aids to help maximize their remaining sight and assistive technologies like text-to-speech computer programmes.

If someone in your family is affected with RP, you can access genetic testing along with support from a genetic counsellor. As well as helping you to make informed medical and personal decisions, a genetic diagnosis will also provide up-to-date information about potentially suitable new treatments that are in development.

Have your eyes tested every two years even if you think your vision is fine. An eye test can spot some eye conditions and, if caught early, treatment may prevent further deterioration.

Last updated July 2019
Approved by Prof Alison Hardcastle, University College London Faculty of Brain Sciences

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