Alga extract improves vision in retinitis pigmentosa
medwireNews: An alga extract that is rich in β-carotene is effective for improving retinal function in people with retinitis pigmentosa (RP), results of a randomized placebo-controlled trial show.
The investigators say that Dunaliella bardawil alga powder may represent a promising new therapeutic approach for some patients with RP, which is a leading cause of incurable inherited blindness.
RP has various causes, one of which is a defect involving enzymes of the retinoid cycle. This study evaluated the effects of oral treatment with D. bardawil, which is rich in 9-cis β-carotene, a known precursor of retinal.
Using a randomized crossover design, 34 adults with RP were administered capsules containing 300 mg of D. bardawil powder (equivalent to 20 mg of β-carotene) or placebo. Each treatment period lasted 90 days with a 90-day washout in between.
The study’s primary endpoint was the change in dark-adapted maximal electroretinographic b-wave amplitude. This parameter increased by 8.4 μV following treatment with D. bardawil and declined by 5.9 μV with placebo, a statistically significant difference.
Secondary endpoints also supported the efficacy of D. bardawil treatment. More than one-third of participants had at least a 10.0 μV increase in dark-adapted b-wave amplitude in both eyes on active therapy, versus none of the patients on placebo.
Also, light-adapted b-wave response increased by 17.8% with D. bardawil versus a decline of 3.0% with placebo, a statistically significant effect.
There were no differences between groups in visual field or best-corrected visual acuity, however. Importantly, no adverse effects were seen.
Writing in JAMA Ophthalmology, Ygal Rotenstreich (Sheba Medical Center, Tel-Hashomer, Israel) and colleagues say that a subset of patients typically showed “clear improvements in both objective and subjective retinal functions” following 90 days of treatment with the alga powder.
They conclude: “Pending more radical therapeutic methods, including gene and stem cell therapies, 9-cis β-carotene treatment might help some patients with RP… It seems likely that future treatments will include 9-cis β-carotene–based restoration in combination with other approaches that increase the survival of altered photoreceptors.”
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Joanna Lyford, Senior medwireNews Reporter