Medication Summary
The goals of pharmacotherapy are to reduce morbidity and to prevent complications. In addition to the medications listed below, the use of lutein to human disease(s) is uncertain, although lutein apparently may slow retinal degeneration. Doses of 20 mg/d have been recommended.
Voretigene neparvovec (Luxturna) is the first gene therapy approved by the FDA that targets the RPE65 gene.
Although bilberry is recommended by some practitioners of alternative medicine in doses of 80 mg/day, no controlled studies exist documenting its safety or efficacy in treating RP.
Vitamins, Fat-Soluble
Class Summary
May delay RPE degeneration.
Vitamin A (Aquasol A, A-Natural, A-25)
Use of antioxidants in treating RP might be beneficial, but no evidence exists in favor of vitamin supplementation and possibly some slight evidence to the contrary. A comprehensive epidemiologic study by Norton et al concluded that very high daily doses of vitamin A palmitate (15,000 U/d) slow the progress of RP by about 2% per year. The effects are also modest, and the use of such treatment must be weighed against the uncertain risk of long-term adverse effects from large chronic doses of vitamin A. Yearly checks of liver enzymes and vitamin A levels are recommended.
While vitamin A is found almost exclusively in animals (eg, fish oil, liver), beta-carotene is found predominantly in leafy green vegetables. Beta-carotene has about one-sixth the bioavailability of vitamin A and is cleaved by the intestinal mucosa using the enzyme dioxygenase. It is reduced with 2 NADPH into retinol or vitamin A. Because of the body's limited ability to generate vitamin A from beta-carotene, it is nontoxic, even in amounts 6 times more than the US RDA.
Vitamin E (Aquasol E, Alph-E, Aqua Gem-E)
High doses of vitamin E (400 U/d) were modestly deleterious, according to Berson et al, nevertheless, doses as high as 800 IU/d have been recommended.
Ascorbic acid (Acerola, C-Gel, Ascocid, Vita-C)
Although doses of 1000 mg/d are recommended anecdotally, according to Naka et al, no evidence exists that ascorbic acid is helpful in RP.
Calcium channel blockers
Class Summary
Reduce toxic levels of cyclic GMP in the RPE.
Diltiazem (Cardizem, Diltzac, Tiazac)
Experimental therapy. A recent study by Frasson showed decreased degeneration of the retina in rd mutant mice. Homologous mutations in humans represent about 4% of patients with RP. No current recommendations exist regarding the use of diltiazem, a calcium channel blocker commonly used in cardiac disease, in any patients with RP, including those with the homologous mutation.
Carbonic anhydrase inhibitors
Class Summary
Reduce cystoid macular edema associated visual loss from RP.
Acetazolamide (Diamox Sequels)
In a small percentage of patients with RP, cystoid edema may respond to oral carbonic anhydrase inhibitors, such as acetazolamide, with some subjective improvement in visual function, according to Fishman et al. These may be patients in whom the macular RPE is relatively uninvolved by disease, since carbonic anhydrase inhibitors must act upon functional RPE to enhance water transport, according to Marmor. Topical CAIs have not been evaluated.
Methazolamide (Neptazane)
Reduces aqueous humor formation by inhibiting enzyme carbonic anhydrase, which results in decreased IOP.
Retinal Gene Therapies
Class Summary
Mutations in the human retinal pigment epithelial 65-kd protein (RPE65) gene are one of the causes of retinitis pigmentosa and Leber congenital amaurosis (a form of retinitis pigmentosa at birth). Voretigene neparvovec is the first gene therapy that targets the RPE65 gene.
Voretigene neparvovec (Luxturna)
Indicated for confirmed biallelic (ie, having both a paternal and a maternal mutation) RPE65 mutation-associated retinal dystrophy in patients aged 1 year and older. It is an adeno-associated virus vector-based gene therapy designed to deliver a normal copy of the gene encoding RPE65 to cells of the retina.
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Usher syndrome with typical retinitis pigmentosa appearance.
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Choroideremia.
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Bull's eye maculopathy seen in cone dystrophy.
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Polydactyly seen in Bardet-Biedl syndrome (associated with retinitis pigmentosa).
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Cone dystrophy.
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Gross pathology of an eye in a man with retinitis pigmentosa.
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Leber congenital amaurosis.
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Female carrier of choroideremia.
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Representative electroretinograms of patients with healthy eyes, rod-cone dystrophy, and congenital stationary night blindness. Courtesy of Dr. Nusinowitz, Jules Stein Eye Institute.
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Representative electroretinograms of patients with healthy eyes and X-linked retinoschisis. Courtesy of Dr. Nusinowitz, Jules Stein Eye Institute.
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Retinitis pigmentosa pigmentation pattern demonstrated with ultrawide fundus imaging using the scanning laser ophthalmoscope (Optomap; Optos PLC, Dunfermline, Scotland, United Kingdom).
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Fellow eye of same patient as in the image above, again demonstrating a typical retinitis pigmentosa pigmentation pattern demonstrated with ultrawide fundus imaging using the scanning laser ophthalmoscope (Optomap; Optos PLC, Dunfermline, Scotland, United Kingdom).
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Higher resolution image of typical bone spicule formation.
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Cone dystrophy demonstrating typical central macular atrophy found in this condition.
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Retinitis pigmentosa, rubella, a history of retinal detachment, and syphilis all may result in a hyperpigmented retinal pigment epithelium (RPE) with bone spicule appearance, restricted visual field and/or poor vision, and atrophic vessels.
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Retinitis pigmentosa progresses over decades. Associated cataract also is relevant, as seen in this image.
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Pigmentary changes are not always seen in retinitis pigmentosa but frequently are observed, as in this patient with Alström disease.
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Genetic screening may be helpful in identifying patients who are at risk, in counseling, and in directing treatment as new knowledge is acquired. Some varieties of retinitis pigmentosa may have increased vulnerability to environmental hazards; for example, one might avoid light exposure in some rhodopsin mutations or sildenafil in phosphodiesterase mutations. Patients with retinitis pigmentosa may have other findings. This patient with Alström disease shows acanthosis.
