Retinitis Pigmentosa Sufferers May Benefit from Vitamins and Herbs

By Belinda Clarke, B. SC., N.D.

Retinitis pigmentosa is a slowly progressive, bilateral degeneration of the photoreceptor cells in the retina. Irregular black deposits of clumped pigment in the peripheral retina, called bone spicules give the disease its name. The name however is actually a misnomer because while the suffix itis denotes inflammation, retinitis pigmentosa is not an inflammatory process. It is a general term for a disparate group of dystrophies affecting the rod and cone cells.

Rod cells are concentrated along the outer perimeter of the retina and provide us with peripheral vision, as well as helping us to see in dark or dimly lit environments. Cones are concentrated in the macula and allow us to see colour and perceive fine detail in the centre of our vision. Together they are responsible for converting light into the electrical impulses that our brains translate into images.

How the symptoms of retinitis pigmentosa present vary considerably, depending in part on whether the process is primarily a rod-cone or cone-rod dystrophy. Most forms will affect the rod cells first and are known as rod-cone types of dystrophies. These patients most often present with night vision problems. The night vision loss will progress to a slow loss of peripheral vision, sometimes in the form of a ring of vision loss in the mid periphery with islands of clear vision in the very far periphery (known as a ring scotoma), and other times in the form of tunnel vision, always sparing central vision for the longest. Cone-rod dystrophies first affect the cone cells and central vision. Patients will present with day vision problems and suffer from a gradual loss of visual acuity and colour discrimination, eventually leading to rod damage and the associated symptoms.

Genetically, retinitis pigmentosa is often passed from one generation to the next by one of three inheritance patterns. The incidence worldwide is approximately one in 4,000, occurring slightly more frequently in men than women because of the incidences of X-linked inheritance. Being among the most specialized cells in the body, retinal cells depend on numerous genes to create vision. Researchers have found over 100 genes that can contain mutations leading to retinitis pigmentosa. This disorder is therefore often associated with other genetic syndromes. It is also important to note that over half of the diagnosed cases are primary retinitis pigmentosa and as such have no known genetic cause.

The age of onset of retinitis pigmentosa will vary, depending often on the associated disorder. It is usually diagnosed in young adulthood, but can occur anywhere from infancy to mid 50’s. Gradual vision loss will ultimately result in blindness between the ages of 30 and 80.

While medically there is no known cure for retinitis pigmentosa, a number of complementary therapies have been shown to slow the disease progression. Photoreceptor cells have high oxygen content and a high concentration of fatty acids, making them particularly vulnerable to free radical damage, and this damage has been shown to play an important role in the progression of the disease. Eating foods high in antioxidants, especially the carotenoids and Vitamin A, is essential to eye health. These compounds are found in green and yellow vegetables and fruits such as carrots, cantaloupe, squash, broccoli, spinach, peppers, and papaya, and also in fish liver oil. The role of food sensitivities is less clear, but there are a number of reports of significant visual improvements in cases of retinitis pigmentosa with the identification and elimination of offending foods.

Certain supplements have also shown positive results. Lutein, one of the carotenoids, filters harmful light bands and thus protects the eye from free radical damage caused by UV light, slowing retinal degeneration. Vitamin A, or its precursor form, beta carotene, is a powerful antioxidant with a specific affinity for the eye. Supplementation has been shown to retard the rate of deterioration as measured by electroretinography (ERG.) The amino acid taurine is essential for normal vision and strongly recommended as a supplement for retinitis pigmentosa. Vitamin C may also be beneficial, as well as calcium and Vitamin D. Vitamin E supplementation is somewhat controversial; some studies show benefits while others suggest that Vitamin E may have a deleterious effect on the progression of the disease.

The herb bilberry (Vaccinium myrtillus) in a standardized extract of 25% anthocyanadin content has also shown benefits, especially when taken with beta carotene. The patients who tried it demonstrated adaptation to light and night vision, and enlargement of the visual field. Finally, a number of successful cases have included homeopathic and/or acupuncture treatments in conjunction with nutritional supplements.

Eating a diet high in a variety of fruits and vegetables, and adding a few nutritional supplements, may be the best way to slow the progression of this serious and debilitating disorder.