Approach

While Retinitis pigmentosa (RP) has no cure, many patients can significantly benefit from optimising 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 consultant (either an ophthalmologist or optometrist), who can help them obtain various visual aids such as glasses, magnifiers, or telescopes.

Vitamin A (retinol)

Although high doses of oral vitamin A (retinol) were previously recommended to slow the decline of retinal function, based on a historical randomised clinical trial data, this recommendation no longer applies. One study published in 2023 re-evaluated the historical data, and sequence banked DNA samples from the original trial to determine whether certain genotypes responded preferentially to vitamin A (retinol) supplementation.[38]​ The authors found that baseline electroretinogram (ERG) 30 Hz cone flicker implicit time (the time it takes for the retina to fully respond to dim light) was an independent and strong predictor of RP progression for subjects enroled in the clinical trial. In contrast, there was no evidence for a generalised neuroprotective effect of vitamin A (retinol) supplementation in this patient population.[38]​ This study has fundamentally changed understanding of the role vitamin A (retinol) supplementation in the management of patients with RP.[8]

Furthermore, patients with cone-rod dystrophy should avoid vitamin A (retinol), 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.[39] 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.[40] Long-term high-dose vitamin A (retinol) supplementation can also elevate liver enzymes and triglycerides, and increase the risk of osteoporosis.[41] Patients receiving vitamin A (retinol), notably children, older adults, or patients with liver disease, hyperlipidaemia, high alcohol intake, or a combination thereof, should be monitored by their physician for these potential adverse effects.[8]​ 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.[8][42][43]​​

Docosahexaenoic acid (DHA)

DHA is an omega-3 fatty acid and key component of fish oils. It is present in high concentrations in the photoreceptors and may be a precursor for neuroprotective factors.[8]​ Two randomised studies in patients with RP did not show a significant benefit of DHA supplementation.[44][45]​​ One 4-year single-site phase 2 clinical trial evaluating the efficacy of DHA in patients with X-linked RP also showed no therapeutic benefit in slowing the rate of cone ERG functional loss.[46] Many centres still recommend DHA supplementation due to the theoretical benefit, low risk, and minimal side effect profile.[47]

Lutein

Lutein is a dietary carotenoid, found in the human retina and dark green leafy vegetables. A randomised controlled trial examined the efficacy of lutein to slow visual field loss in patients with RP who were taking vitamin A.[48] The study showed a reduction in the loss of mid-peripheral visual fields.[48] However, others have challenged the conclusions of this study.[49]

Cystoid macular oedema (CMO)

Carbonic anhydrase inhibitors such as topical dorzolamide or oral acetazolamide are effective for treatment of CMO in some patients.[50][51] Patients must often remain on these drugs 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 drugs such as paraesthesias 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 oedema before cataract extraction because this can worsen after surgery. Occult weak zonules require appropriate surgical precautions to minimise 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 biallelic RPE65 mutations when injected into the subretinal space.[52][53][54][55][56][57]​​​ A subsequent phase 3 trial showed improved functional vision in patients with RPE65-mediated inherited retinal dystrophy who were treated with voretigene neparvovec.[58] Follow-up studies of the phase 3 trial and an earlier phase 1 trial demonstrated a consistent safety profile and longer-term efficacy.[59][60]​​​

Many other clinical trials for novel therapeutics to treat other forms of RP and Leber congenital amaurosis have been completed or are currently underway.[61]​ [62][63][64]

Use of this content is subject to our disclaimer