What is Retinitis Pigmentosa?
Retinitis pigmentosa (RP) is the name given to a diverse group of inherited eye disorders. These eye conditions affect a part of your eye called the retina.
RP causes permanent changes to your vision, but how much and how quickly can really vary from person to person. These retinal changes can affect your side vision, which makes it harder for you to see in dim light or the dark, and central vision, which causes difficulty with detailed activities such as reading or watching television.
If you have RP, sight loss is gradual and usually progresses over a period of many years. Some people with RP might become blind but most people with RP keep some useful vision well into old age.
Symptoms of Retinitis Pigmentosa
In most of the more common forms of RP, the first symptoms occur between childhood and the age of 30. The first symptom you usually notice is that you find it difficult to see in poor light, such as outdoors at dusk, or in a dimly lit room. This is often referred to as “night blindness”. While most people find it takes their eyes about 20 minutes to adapt to dim light, if you have RP it will either take you much longer or it won’t happen at all.
A second symptom is often the loss of some of your peripheral vision or peripheral visual field. This means that when you’re looking straight ahead you become less able to see things either to the side, above or below. Difficulty seeing in low light and loss of peripheral vision are both signs that your peripheral rod cells are being affected by RP.
In some RP-related conditions, central vision is lost first because the central cone cells are affected first. You might find it difficult reading print or carrying out detailed work at this time. In these types of RP, your peripheral vision is affected in the later stages.
All RP conditions are progressive, but the speed and pattern of deterioration of sight varies from one person to another. For most people, the first effect of RP is the gradual loss of peripheral vision. This means that you can start to miss things slightly to the side of you or trip over or bump into things you would have seen in the past. Most people with RP eventually have a very restricted visual field, leaving only a narrow tunnel of vision.
Most people with RP retain useful central vision through their twenties, which means your ability to read and recognise faces is not greatly affected. By 50 years of age most people’s central vision is affected to the extent that reading is a problem without the help of a magnifier.
Many people who have RP find the glare from bright lights and sunlight becomes an increasing problem. Your retinal cells become less able to adapt to changing light levels and it becomes more difficult to use your vision when you move between a light and a dark room.
Causes of Retinitis Pigmentosa
All types of RP affect the retina. The retinal cells gradually stop working and eventually die. In most cases, the peripheral rod cells are affected first and RP later affects the central cone cells. The symptoms you experience depend on the way your retina is affected by RP and can be very different from person to person.
Almost all types of RP are inherited, caused by a fault in the genetic information passed down to you from a parent. The genes you inherit contain the instructions that tell your body how to grow, repair and renew itself. When a gene is faulty these instructions are faulty and the cells using those instructions do not work as they should.
In RP, the faulty genes cause your retinal cells to stop working and eventually die off. Researchers have found many of the genes which, when faulty, cause RP but there is still work to be done to discover them all.
As there are many genes that can cause the retinal cells to stop working, there are many different types of RP. This is why RP is described as a group of inherited retinal disorders. RP is often mentioned alongside other eye conditions with similar genetic causes and effects on vision, such as Leber’s Congential Amaurosis, cone and cone-rod dystrophies, and Choroideremia.
Prevention / Treatment of Retinitis Pigmentosa
Currently, there is no known cure or treatment for RP or associated retinal disorders. Many research groups around the world are working on different aspects of the condition with the aim of developing treatments. Many of the genes causing RP and related conditions are being discovered (or mapped) and it is this understanding of where the faults occur in the genetic information that may enable potential treatments to be devised. It is possible that eventually one or more treatments may be devised, which will combine the knowledge gained from some of the following avenues of research. Most of the work so far has only been carried out in the laboratory, which means it could be a number of years before this research produces a tried and tested treatment.
What do I do now?
Galloway’s promotes the importance of regular eye tests. Many conditions can be halted or improved with early detection and intervention. If you are worried you may have experienced the symptoms described, please contact your local optometrist and book an eye test without delay.
If you have been diagnosed with Retinitis Pigmentosa, there are many ways in which Galloway’s can help you and your loved ones come to terms with the diagnosis and can offer simple practical help with living with the diagnosis and coping with every day life.