Approach

While RP has no cure, many patients can significantly benefit from optimizing their remaining vision. All patients should undergo a sight test to have their refractive ability checked. Many patients will benefit from assistance from a low-vision specialist (either an ophthalmologist or optometrist), who can help them obtain various visual aids such as glasses, magnifiers, or telescopes.

Vitamin A and docosahexaenoic acid (fish oils)

High doses of oral vitamin A slow the rate of decline of retinal function, as measured by electroretinogram responses.[30] Vitamin A supplementation is routinely recommended by some centers but opposed by others. Patients with cone-rod dystrophy should avoid vitamin A, due to the potential hazards that have been observed in mice with ABCA4 mutations, which had more accumulation of phototoxic A2-E (N-retinylidene-N-retinylethanol-amine) compounds.[31] A2-E is detrimental to retinal pigment epithelial (RPE) cell function by a variety of mechanisms, including inhibition of lysosomal degradative capacity, loss of membrane integrity, and phototoxicity.[32] Long-term high-dose vitamin A supplementation seems safe for other variants of RP, but it can elevate liver enzymes and triglycerides and increase the risk of osteoporosis.[33] Patients receiving vitamin A should be monitored by their physician for these potential adverse effects. The decision to use or not use vitamin A will depend on the center and patient preference. The use of vitamin A has not been studied in children with RP and therefore is usually avoided. Beta-carotene (a precursor of vitamin A) has been suggested to be beneficial in the treatment of retinitis pigmentosa, but these results are still preliminary and require further study before a formal recommendation can be made.[34][35]

Docosahexaenoic acid (DHA) is a fatty acid present in high concentrations in the photoreceptors and may be a precursor for neuroprotective factors. Two randomized studies in patients with RP did not show a significant benefit of DHA supplementation.[36][37] One 4-year single-site phase II clinical trial evaluating the efficacy of DHA in patients with X-linked RP also showed no therapeutic benefit in slowing the rate of cone electroretinography (ERG) functional loss.[38] Many centers still recommend DHA supplementation due to the theoretical benefit, low risk, and minimal side effect profile.[39]

Lutein

Lutein is a carotenoid, found in the human retina and dark green leafy vegetables. A randomized controlled trial examined the efficacy of lutein to slow visual field loss in patients with RP who were taking vitamin A.[40] The study showed a reduction in the loss of mid-peripheral visual fields.[40] However, others have challenged the conclusions of this study.[41]

Cystoid macular edema (CME)

Carbonic anhydrase inhibitors such as topical dorzolamide or oral acetazolamide are effective for treatment of CME in some patients.[42][43] Patients must often remain on these medicines for several months before an effect is seen. The effect can wear off with time, and some patients do not benefit. Furthermore, some patients cannot tolerate the adverse effects of these medicines such as paresthesias and frequent urination.

Cataracts

Posterior subcapsular cataracts are especially common and often affect central vision. Cataract extraction can benefit many patients, especially if the degeneration has not involved the central macula. It is important to rule out the presence of cystoid macular edema before cataract extraction because this can worsen after surgery. Occult weak zonules require appropriate surgical precautions to minimize the risks of complications during cataract surgery.

Gene replacement therapy

Voretigene neparvovec, a recombinant adeno-associated virus vector carrying a normal copy of the RPE65 gene, has demonstrated improved vision in patients with Leber congenital amaurosis secondary to mutations in the RPE65 gene when injected into the subretinal space.[44][45][46][47][48][49] A subsequent phase 3 trial showed improved functional vision in patients with RPE65-mediated inherited retinal dystrophy who were treated with the AAV vector-based gene therapy, voretigene neparvovec.[50] Follow-up studies of the phase 3 trial and an earlier phase 1 trial demonstrated a consistent safety profile and developing longer-term efficacy.[51] Voretigene neparvovec is approved for the treatment of biallelic RPE65 mutation-associated retinal dystrophy. Voretigene neparvovec is not only the first approved treatment for retinal dystrophy, but is the first approved gene therapy for the eye. Other clinical trials for Usher syndrome type 1 due to mutations in MYO7A, and X-linked RP due to mutations in RPGR are underway.

Use of this content is subject to our disclaimer