Vitamin A is important for our eyesight because it is responsible for helping the retina, at the back of our eye, to see clearly. The retina contains photoreceptor cells that detect light and send signals through the optic nerve to the brain. The more light that reaches these cells, the more they are able to produce visual information in our mind.
Retinitis Pigmentosa is an inherited condition that causes gradual loss of vision, starting in childhood or adolescence. Patients with this condition suffer from night blindness, loss of peripheral vision, and tunnel vision before eventual total blindness.
Although there is no cure for Retinitis Pigmentosa, supplements have been shown to slow or even stop its progression in some cases. Vitamin A supplements can be very effective in treating Retinitis Pigmentosa because they increase vitamin A levels in your body by converting carotenoids into retinol.
Vitamin A For Retinitis Pigmentosa
Purpose : Three clinical trials were performed between 1984 and 2008 to test the hypothesis that vitamin A supplementation alone or in combination with DHA or lutein can slow the rate of progression of retinal degeneration for patients with retinitis pigmentosa (RP). The results of these trials showed that on average, patients taking 15,000 IU of vitamin A per day experienced slower decline in 30 Hz electroretinogram (ERG) response amplitudes than controls (Berson et al Arch Ophthalmol 130: 707, 2012). The goal of this study was to ask if patients with different genetic forms of RP respond to vitamin A supplementation differently.
Methods : 330 subjects were identified who participated in one or more of the three vitamin A clinical trials, and who had sufficient 30Hz ERG amplitudes to avoid floor artifacts. We performed panel-based genetic testing for subjects who did not have genetic diagnoses from prior studies. Robust linear regression and mixed regression models were used to construct exponential rate of decay estimates for each subject, grouped by gene and vitamin A treatment status.
Results : 189 subjects with genetic diagnoses were available for analyses, including 126 in the vitamin A treated group, and 63 in the control group. 47 had mutations in USH2A, 35 in RHO, 28 in RPGR, 11 in PRPF31, and 8 in PRPH2. The rate of loss of retinal function of subjects with USH2A mutations was faster than that in other genotypes (p<0.0001), and slower with PRPH2 mutations (p=0.04). Subjects with RHO-associated RP (N=35) who took vitamin A did not have a significantly slower rate of decline of 30Hz amplitude than controls (-8.3% vs -7.6%/year, p>0.05). Vitamin A supplementation appeared to reduce the rate of decline in retinal function for subjects with PRPH2-associated RP: -3.8%/yr in controls (N=5) versus +2.1%/yr in the vitamin A group (N=3), p=0.007.
Conclusions : The treatment effect of vitamin A did not appear to be concentrated in patients with specific genetic causes of disease. One small genetic subgroup of patients with PRPH2-associated RP showed a larger than average vitamin A treatment effect, but this finding was based on a small number of subjects. These data suggest that the previously observed benefit of vitamin A supplementation for adults with typical RP applies broadly for patients with different genetic forms of disease, within the limits of the sample sizes evaluated.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Children with retinitis pigmentosa who received vitamin A supplementation were associated with slower rate of cone electroretinogram amplitude compared to children who did not, a small study found.
The estimated mean rate of change smaller in the vitamin A cohort for children with this rare genetic disorder compared to children who did not receive vitamin A (-6.2% per year versus -13.2% per year, P=0.01), reported the late Eliot L. Berson, MD, of Massachusetts Eye and Ear Infirmary in Boston, and colleagues.
Writing in JAMA Ophthalmology, the authors highlighted their own 1993 trial in the Archives of Ophthalmology that found that oral vitamin A slowed the course of retinal degeneration in adults with retinitis pigmentosa. After further study, the National Eye Institute recommended in 2008 that “most adults with retinitis pigmentosa and normal liver function should take vitiman A palmitate.”
But they noted that patients younger than age 18 were not included in the study, but some parents asked them if their children could take vitamin A. They were told to eat a regular diet, avoid high-dose vitamin E supplement, monitor serum liver function annually and return for a follow-up assessment and dose adjustment every two years. There were a minority of children who did not pursue treatment after advice from their pediatrician, but still returned for follow-up assessment every 2 years. These two groups of children comprised the cohort in this study — one group where children consistently took vitamin A, and one where they did not receive vitamin A.
An accompanying editorial by Caroline Klaver, MD, and Alberta Thiadens, MD, both of Erasmus Medical Center in Rotterdam, The Netherlands, noted the work of the original study by Berson, who died earlier this month just short of his 80th birthday. They briefly eulogized him, noting his reports on “nutritional treatment for retinitis pigmentosa were groundbreaking and regarded by most as creative and intelligent solutions to reduce the slope of progression of this devastating disease.”
Klaver and Thiadens added that others argued “these reports were merely a proof of concept that needed more in-depth validation before accepting it as profound evidence,” but that this new study “adds another building block” to the evidence for vitamin A supplementation being beneficial for patients with retinitis pigmentosa.
And still uncertain is the mechanism by which vitamin A may slow the disease’s progression, the editorialists said. They reviewed the substance’s interactions with retinal cells, which are multifold, and noted several possible mechanisms — such as somehow overcoming a genetic defect — but admitted that the available evidence doesn’t allow a firm conclusion.
“As great scientists do, Eliot Berson has managed to raise a mysterious and intriguing issue even after his decease,” Klaver and Thiadens concluded.
The researchers included 55 children in the vitamin A cohort — over two-thirds were boys, and almost 90% were white. In 25 members of the control cohort, three-quarters were boys and 100% were white. The mean age of both cohorts was around 9. Children were followed up for about 5 years in the vitamin A cohort and about 4.5 years in the control cohort. However, the authors noted that while over two-thirds of the vitamin A cohort returned for a follow-up examination within the recommended 2 years, only 40% of the control cohort did.
The primary outcome was the mean exponential rates of change of full-field cone electroretinogram amplitude without and with adjusting for potential confounders. But the authors found that even in adjusted analyses, there was still a significantly slower rate of decline among the vitamin A cohort.
They argued that based on these estimates, “falling to half baseline amplitude occurred, on average, in 4.9 years in the control cohort and 9.7 years in the vitamin A cohort, a nearly 2-fold difference.”
Examining ocular safety, Berson and colleagues found no significant difference between groups with respect to mean rates of change of visual field or visual acuity, the proportions of children whose visual field diameter fell to 20° or less or whose visual acuity fell to 20/200 or less in at least 1 eye during follow-up.
Limitations to the data included its small sample size and retrospective, observational design, with the authors noting that it is “more limited in its implications than the randomized clinical trial in adults that preceded it.”
retinitis pigmentosa treatment
What is retinitis pigmentosa?
Retinitis pigmentosa is the name of a group of eye diseases that are passed down in families. All the diseases involve the eye’s retina. The retina is the nerve layer that lines the back of the eye that is sensitive to light. All the diseases cause a slow but sure loss or decline in eyesight.
What causes retinitis pigmentosa?
Retinitis pigmentosa is part of a group of eye diseases that are passed down in families. All of them affect the ability of the retina to sense light. The problem with the retina can take place in any of the following:
- Rod cells
- Cone cells
- The link between the cells that make up the retina
What are the symptoms of retinitis pigmentosa?
The symptoms of retinitis pigmentosa usually begin in childhood or adolescence. However, each person may experience symptoms differently. Some people with the problem have a slow, very progressive loss of eyesight. Others lose their eyesight much more quickly and severely. Common symptoms may include:
- Hard time seeing in poor lighting or in the dark
- A reduced ability to see either central vision or side or peripheral vision
- Hard time reading print
- Hard time figuring out detailed images
- Hard time with stumbling or tripping over objects not seen
The symptoms of the condition may look like other eye diseases. Talk with your eye healthcare provider for a diagnosis.
How is retinitis pigmentosa diagnosed?
Your eye healthcare provider will take a complete medical history and give you an eye exam. The eye healthcare provider may do one or more of the following tests to make a diagnosis:
- Eye chart test
- Refraction test
- Color defectiveness determination test
- Retinal exam
- Ultrasound of the eye
How is retinitis pigmentosa treated?
Your eye healthcare provider will figure out the best treatment for you based on:
- Your age
- Your overall health and medical history
- How sick you are
- How well you can handle specific medicines, procedures, or therapies
- How long the condition is expected to last
- Your opinion or preference
The symptoms of retinitis pigmentosa sometimes look like other conditions or medical problems. Always see your eye healthcare provider for a diagnosis.
At this time, there is no specific treatment for retinitis pigmentosa. However, protecting your eye’s retina by using UV sunglasses may help delay the start of symptoms.
A retinal prosthesis (artificial retina) has been developed for individuals with very advanced disease and severe vision loss. Talk with your eye healthcare provider for more information.
What are the complications of retinitis pigmentosa?
Retinitis pigmentosa causes a progressive loss of eyesight. It may happen slowly or more quickly.
Living with retinitis pigmentosa
Retinitis pigmentosa is a progressive condition. This means that it will continue to get worse over time. Talk with your eye healthcare provider to get information on services and devices for people with low vision.
When should I call my healthcare provider?
If your symptoms get worse or you have new symptoms, call your eye healthcare provider.
Key points about retinitis pigmentosa
- Retinitis pigmentosa is a group of eye disorders that are inherited and involve the eye’s retina
- Retinitis pigmentosa causes a slow but sure loss or decline in eyesight
- Symptoms, including loss of vision or visual sharpness, usually begin in childhood or adolescence
- Currently, there are no treatments for retinitis pigmentosa
- The use of UV sunglasses may help delay the start of symptoms
Tips to help you get the most from a visit to your healthcare provider:
- Know the reason for your visit and what you want to happen.
- Before your visit, write down questions you want answered.
- Bring someone with you to help you ask questions and remember what your provider tells you.
- At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.
- Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
- Ask if your condition can be treated in other ways.
- Know why a test or procedure is recommended and what the results could mean.
- Know what to expect if you do not take the medicine or have the test or procedure.
- If you have a follow-up appointment, write down the date, time, and purpose for that visit.
- Know how you can contact your provider if you have questions