This is a term which is used for a group of eye diseases which can lead to loss of sight. These eye diseases have in common is the coloring which your doctor sees when he looks at the retina. Retina is a bundle of tissue at the back of your eye. The cells in the retina are called photoreceptors. When you have retinitis pigmentosa, then photoreceptors do not work the way that they are supposed to and as the time passes, you lose your sight. This is a rare disorder which is passed from parent to child.
There are some studies in which are said that only 1 out of every 4,000 people get it. About a half of people who are diagnosed with retinitis pigmentosa have a family member who also have this condition. The retina has two types of cells which gather light, known as rods and cones. The rods are located around the outer ring of the retina and they are active in dim light.
In the most cases of retinitis pigmentosa, firstly are affected rods. Your ability to see to the side (known as peripheral vision) and your night vision go away. Mostly, cones are in the center of your retina. Cones can help you to see color and fine detail. When the retinitis pigmentosa is affecting them, then you slowly lose your central vision and your ability to see color.
Retinitis Pigmentosa Symptoms
Usually, the retinitis pigmentosa starts in childhood. It varies from one person to another when exactly will start it and how quickly it will get worse. Most people who are diagnosed with retinitis pigmentosa lose much of their sight by early adulthood and by the age of 40 these people are often legally blind. Usually, the rods are affected first so the first symptoms which you may notice is that it takes longer to adjust to darkness (known as night blindness).
You can notice this when you walk from bright sunshine into a dimly lit theater. You may not be able to drive at night or you can trip over objects in the dark. Also, you may lose your peripheral vision at the same time or as soon after your night vision declines. Also, you can get tunnel vision that means that you cannot see things to the side without turning your head. In later stages of retinitis pigmentosa, your cones can be affected.
This will make harder for you to do detail work and you can have problems with seeing colors. This is a rare, but in some cases cones can die first. Also, you can find that bright lights are uncomfortable for you which is a symptom of condition that doctors call photophobia. You can star to see flashes of light which blink or shimmer. This condition is known as photopsia. Your doctor can tell if you have retinitis pigmentosa. He will look into your eyes and he will do some special tests, such as genetic test; electroretinogram, visual field test or ophthalmoscope.
Retinitis Pigmentosa Causes
There are more than 60 different genes which can cause different types of retinitis pigmentosa. Parents can pass the problem genes on their children in 3 different ways:
- Autosomal recessive retinitis pigmentosa: Each parent has one normal copy and one problem copy of the gene which is responsible but parents do not have any symptoms. The child which has inherited two problem copies of the gene (one from each parent) will develop this type of retinitis pigmentosa. The two copies of the problem gene are needed which means that each child in the family has 25% chances of being affected.
- Autosomal dominant retinitis pigmentosa: In this type of retinitis pigmentosa is required only one copy of the problem gene to develop. The parent, who has that gene, has a 50% chance of passing it to each child.
- X – linked retinitis pigmentosa: The mother who carries the problem gene, can pass this gene to her children. Each of her children has 50% chances of getting it. Most women, who carry this problem copy, will not have any symptoms. But, there are some studies in which are said that about one in every five will have mild symptoms.
- Most men, who will get this problem copy, will have more severe cases. Fathers, who have this problem gene, cannot pass to their children.