Retinitis pigmentosa is a genetic eye condition which causes retinal damage. It affects one in every 4000 people in the world. Although rare, the condition can result in severe impairment of vision.
The retina contains cells known as photoreceptors that begin the visual process. They consist of two types, cones and rods. The cells are responsible for converting light into electrical signals. The optic nerve then carries this information to the brain. The brain plays the role of interpreting the signals as images. When any issues arises with the cells, vision is threatened.
Also Known As
- Autosomal dominant RP
- Autosomal recessive RP
- X-linked RP
Causes and Risk Factors
Retinitis pigmentosa is a genetic disease. There are over 60 genes that can cause the disorder. When these genes are in the body, they carry the wrong instruction for the making of proteins required by the photoreceptors. The gene can be passed to a child from one or both of the parents. The types of retinitis pigmentosa depends on how the genes are passed on. They include:
- Autosomal recessive RP - This is where each parent has a copy of the mutated gene and a normal one. Whereas both are healthy, the child can inherit the two faulty genes and get retinitis pigmentosa.
- Autosomal dominant cells - It occurs when only one parent has the abnormal gene and has the disease. There is a 50% chance that the children will inherit the gene.
- X-linked RP - This is a rare type where only the mother, who is a carrier passes the faulty gene to the male child through the X- chromosome.
The disease affects people of all gender, races and ethnicity. Those at the highest risk are those who are predisposed to the faulty gene.
Signs & Symptoms
The symptoms may vary from person to person depending on the severity of the disease. For most people, the rod cells tend to be the first to be affected. These cells are found on the outer regions of the retina. They allow an individual to see in a dim or dark environment. Once damaged, symptoms that follow include poor night vision and loss of peripheral (side) vision.
With the progression of the disease, the cones also get damaged. These are located in the central portion of the retina. They are responsible for color perception, central vision and acuity. Retinal pigmentosa at this stage will cause narrowed field vision and a problem with colors and details.
Other signs and symptoms to expect are light sensitivity and eventual loss of vision.
The diagnosis is made to assess the health and functionality of the retina. The eye care professional may carry out tests such as the following:
- Ophthalmoscope exam – The test utilizes the ophthalmoscope to magnify the view of the retina. It usually shows whether there are any dark and abnormal pigment deposits at the back of the eye. Presence of the deposits can indicate retinitis pigmentosa.
- Visual field test – The test assesses for the degree of view within the front and side scope. Retinitis pigmentosa is associated with loss of central or side vision.
- Electroretinogram – The device tests the electrical activity of the photoreceptors. This is possible through the electrodes which measure the response of the rods and cones. Photoreceptors that are not working as they should indicate a problem in the cells.
- DNA sampling – Gene testing can be done to confirm the hereditary gene
The treatment for retinitis pigmentosa is aimed at retaining the vision left or slowing down vision loss. It also focuses on making the vision problems more manageable.
Retinitis pigmentosa does not have a cure. However, it is manageable. Eye doctors may recommend Vitamin A and fish oil supplements to help slow down progression of the disease. They may also issue Acetazolamide for advanced stages where the macular swells. The drug assists in easing the edema and improving vision.
Where there is significant vision loss, the doctor can prescribe optical field-expanding lenses. These special glasses magnify the central vision to create a wider field. They also help with reducing glare.
In some instances, the patient may opt for an artificial retina. An implant, referred to as the Argus II, is a device that is promising when it comes to restoring vision in individuals with a damaged retina. It is surgically inserted in people who are in the advanced stages of retinitis pigmentosa. The device is paired with glasses which feature a camera.
When at home, the patient can wear sunglasses to protect the eyes from harmful UV rays and to maintain vision. Where there’s significant loss of vision, low visual aids can make life more convenient. The aids include:
- Portable lighting devices that will help to adjust in dark places
- Eye scanning technologies
- Computer programs that read texts
Retinitis pigmentosa will cause severe impairment in vision if not well managed. If not treated at all, other complications such as macular edema or cataracts can easily occur. However, with the right approach, the advancement of the disease can be significantly slowed down.
The disease can not be prevented as it is hereditary. Those at risk should however be on the watch out by going for regular check-ups. Early detection of the disease makes it easier to manage.