After studying 80 children diagnosed with retinitis pigmentosa (RP), researchers found those taking age-adjusted doses of vitamin A had significantly slower cone function loss than those not taking the supplement.

Researchers at the Electroretinography Service of the Massachusetts Eye and Ear Infirmary followed 55 pediatric RP patients taking the supplement and 25 who didn’t for four to five years, both groups with a mean age around nine. Using full-field cone electroretinography (ERG), they found vitamin A supplementation led to a nearly 50% slowing of the mean exponential rate of decline of full-field cone ERG amplitude.

Although researchers have known vitamin A supplementation could potentially slow retinal function loss in adult RP patients, this study adds to the meager understanding of its effects in children, the study authors said.

The unadjusted results show a yearly 13.2% rate of decline in the controls compared with only 6.9% in the treatment group. Adjusted numbers reveal a similar difference. The authors note this amount of benefit in the pediatric participants even exceeds the known benefit in adults—10% per year adult controls vs. 8.3% for those taking vitamin A. Such findings led the authors to speculate that “a vitamin A supplement for patients with retinitis pigmentosa is more effective in childhood,” especially considering the study found no safety concerns.

While the researchers admit the study limitations—smaller sample size and retrospective, observational design—limit the implications, they still suggest children with RP and normal liver function consider taking an age-adjusted dose of vitamin A palmitate. This “could be particularly meaningful to children with a longer cone ERG implicit time who are at higher risk for aggressive disease,” they concluded. “Such supplementation may favor retention of visual field, mobility and vision-related quality of life and maximize the efficacy of other treatment approaches (e.g., gene therapy) that depend on the number and health of remaining cone photoreceptors.”