Are you not able to see during the night?
Do you face difficulty seeing in a movie theater or dimly lit rooms?
Are you stumbling over things that are below or sideways because you could not see them?
If the answer is yes, you might be suffering from a degenerative disorder of the eye called Retinitis Pigmentosa.
Here’s everything you need to know about it.
What is Retinitis Pigmentosa?
Retinitis Pigmentosa ( RP ) is a group of related genetic and degenerative eye disorders which cause severe vision impairment. In RP, the retina, which is the back wall of your eye, is damaged.
So, what is the retina?
The retina is the light-sensitive layer of your eye, it senses light and sends signals to your brain which makes you see. It has 2 types of photoreceptors called rods and cones. Rods help you see in dim light and cones help you see in bright light and also allow you to see colors.
What symptoms will you have?
The symptoms usually appear in childhood and in young adults. Following symptoms may indicate RP.
1. Loss of night vision
The first sign is mostly loss of night vision as rods are affected first.
So if you face difficulty seeing in dim light and dark rooms, you should consider the possibility of RP.
Your vision can be normal during the day.
2. Loss of peripheral vision
Gradually, RP causes blind spots in your side or peripheral vision and merges to form tunnel vision. You will not be able to see things below or at your side.
3. Loss of central vision
The disease progresses over years and damages your cones which
eventually affects your central vision too.
This will make doing detailed work like reading, threading a needle, driving and even recognizing faces difficult for you.
It can result in legal blindness or complete blindness.
4. Color blindness
Some people may also find it difficult to differentiate colors. RP can make you color blind.
What causes Retinitis Pigmentosa?
It is a genetic disorder. There are more than 50 different genes that can cause RP.
It can be inherited from your parents. It has 3 patterns of inheritance: autosomal dominant, autosomal recessive, or X-chromosome linked.
- Autosomal recessive: It can be caused by a recessive gene that means a defective gene from both the parents has been passed on.
- There is a possibility of association with mutations in the X-chromosome.
- It can be autosomal dominant, i.e., mutated genes from just one parent can result in RP in the offspring.
It can occur randomly too, even if there is no case of RP in your family.
If you have other syndromes like Waardenburg syndrome, Alport syndrome, there is an increased chance of you having RP.
What type of Retinitis Pigmentosa do you have?
Retinitis Pigmentosa can be typical or atypical.
1. Typical retinitis pigmentosa
There is dystrophy of rods and cones and mostly rods are affected first. Depending on the relative involvement of your photoreceptors, i.e, rods and cones, there are two major types of retinitis pigmentosa.
- Type 1 RP: In this type, you will experience early and differential loss of rod sensitivity and early signs of diminished night vision. This progresses slowly and leads to region-specific vision loss.
- Type 2 RP: Here, you will have a progressive and combined loss of rods and cones sensitivity and loss of night vision. It occurs usually in adulthood.
2. Atypical Retinitis Pigmentosa
You can have different signs and symptoms as Retinitis Pigmentosa has many atypical forms which represent incomplete forms of the disease. The different types are:
- Retinitis pigmentosa sine pigmento: It has all the clinical features of typical retinitis pigmentosa, except you will have no pigmentary changes in the fundus when your doctor examines.
- Sectorial retinitis pigmentosa: In this form, only one sector of your retina is affected.
- Pericentric retinitis pigmentosa: In this atypical form, pigmentary changes are just confined to an area, immediately around the macula of your retina.
- Retinitis punctata albescens: This is characterized by the presence of many discrete white dots but without pigmentary changes. You may also experience night blindness, narrowing of arterioles, and constriction of your visual field.
How will your doctor diagnose Retinitis Pigmentosa?
There are a number of techniques by which your ophthalmologist can diagnose RP:
1. Eye examination
Your ophthalmologist will use an instrument called the ophthalmoscope which allows a wider, clear view of the retina. If you are healthy, the doctor will see an area called the fundus which is orange to red in color. But if you have RP, you will have abnormal, dark pigment deposits all over the retina.
If your doctor suspects RP, he may confirm the diagnosis by performing an electroretinogram (ERG). This test measures the function of photoreceptors of your retina.
You will be asked to look at a large reflective globe and the doctor will flash different-colored lights into your eyes. An electrode is placed on the eye and a wire transmits the record of the activity of your eye’s retina.
If you have RP, the ERG will show reduced electrical activity indicating that photoreceptors are not functioning properly.
2. Visual field test
Then to estimate the extent of loss of vision, your doctor will perform a visual field test. It will test your peripheral vision and check if any blind spots are developing.
You will be asked to look at a dot of light as it moves around 180 degrees in front and to either side. You will be asked to say when you are not able to see it.
3. Genetic testing
The doctor will take a sample of your blood or other tissues to check if you have mutated or abnormal genes which are associated with RP. It helps in your prognosis and the severity of the disease. It can also help in checking whether gene therapy will be beneficial for you or not.
4. Dark adaptometry
It helps in measuring the threshold of rods as the retina adapts to dark. If you have RP, the threshold is increased and the time to adapt is prolonged. This might help in the early detection of cases.
5. Optical Coherence Tomography
It is an inexpensive and widely available technique that helps in identifying ocular patterns if you have RP.
6. Fluorescein Angiography
It can help you in detecting early deterioration of the retinal epithelium. It is more helpful if the pattern of your inheritance is X-linked.
How is RP treated?
For now, there is no definite treatment for Retinitis Pigmentosa as there are more than 50 genes responsible for RP. But there are some ways to control the progression of the disease:
Diet plays a vital role in improving your vision. Some research shows that vitamin A (about 15,000 international units) helps to slow down the progression of the disease. Vitamin A in the palmitate form is recommended to RP patients.
Though vitamin A toxicity can occur and excessive dosage may lead to nausea, vomiting, headache, dizziness, and liver problems.
You should add fish oil, lutein, DHA, and omega 3 fatty acids to your diet. These act as antioxidants and can also help in slow progression.
2. Artificial retina
A device called the Argus II implant can help patients of late-stage RP. It is a prosthetic device that functions in place of rods and cones. It does not restore normal vision but can help in reading large letters and navigating freely.
Treatment also involves stimulating RPE cells by increasing blood flow in the choroid. This releases neurotrophic factors, improves blood circulation to rods and cones.
3. Gene therapy
In gene therapy, mutated genes are modified or replaced to produce a therapeutic effect. It is beneficial in a form of RP in which both the alleles of the RPE65 gene are affected, i.e. when inherited from both the parents. It can now be treated by injecting medication – voretigene neparvovec-rzyl in the vitreous.
Voretigene neparvovec-rzyl is an adeno-associated virus (AAV) vector-based gene therapy. AAV elicits poor immune responses of the body and AAV2 is the commonly used vector.
It delivers a normal correct copy of the RPE65 gene in the RPE cells and thus, some amount of sight is restored.
A single dose in each eye is recommended by subretinal injection of 0.3ml.It is not recommended for infants.
Gene therapy for the correction of errors of the USH2A gene and RHO gene are also under clinical trials and can help those who have these defective genes.
4. Vision therapy
Vision therapy aims to develop or improve your visual comfort, ease, and efficiency; and change in central visual interpretation.
In this program, reinforcement exercises are performed for over weeks to months under supervision. In addition to exercises, training lenses, prisms, filters, patches, electronic targets, or balance boards are used.
5. Alternate treatment plans
- Stimulation of retinal pigment epithelium by increasing the blood flow of the choroid helps in the release of neurotrophic factors, oxygenation and also improves blood supply to the rod and cone photoreceptor cells in the retina.
This treatment for retinitis pigmentosa is very effective and is provided in India at Sanjeevan.
In advanced cases, the treatment focuses on preventing further degeneration of the eye. The symptoms of night blindness, photophobia, and poor color perception are also treated during the treatment.
- Calcium-channel blockers, intravitreal steroids, and diuretics like acetazolamide also help in delaying the course of RP.
- Special glasses can help if you have photophobia by eliminating glare and they magnify to improve central and peripheral vision.
How is RP treated in Ayurveda?
The treatment of retinitis pigmentosa in Ayurveda depends on the characteristic feature of an individual’s body, time of onset of symptom, and predominant symptom in the patient.
The Ayurvedic treatment is done in 2 stages:
- purification or detoxification
The purification is achieved by ayurvedic techniques like vasti(enema), nasya( instillation of medicine in the nose), swedana (body heating).
After detoxification, certain liquid formulations are administered for the rejuvenation process which strengthens the retina and optic nerve.
You will be advised to improve your diet, practice yoga and certain practices told by your doctor.