Vitamin A slows progression of retinitis pigmentosa in children

Findings from this case-control study support the hypothesis that vitamin A can slow loss of cone function in children with common forms of retinitis pigmentosa (RP).

Study design

The study included 55 patients with RP who took oral vitamin A palmitate supplements (5,000 IU to 15,000 IU daily, depending on age). Twenty-five untreated patients served as controls. The main outcome was the annual rate of change in full-field cone electroretinography amplitude to 30-Hz white flashes.

Outcomes

Patients were followed for a mean of 4 to 5 years. After adjusting for covariates, vitamin A supplementation was associated with almost 50% slowing of the mean exponential rate of decline of full-field cone electroretinogram amplitude compared with controls. The difference between groups was 0.0771 log_e-unit per year (P=0.009).

The incidences of falling to a visual field diameter of 20° or less or a visual acuity of 20/200 or less in at least 1 eye did not differ by cohort.

Limitations

Although the study shows slowing in the rate of loss of cones in the treated group, it did not appear to lead to relevant clinical improvement, as vision was similar between groups. The sample size was relatively small.

Clinical significance 

While not as definitive as randomized controls, the findings suggest vitamin A could be helpful in slowing RP progression in children. In particular, vitamin A supplementation could be beneficial for children at high risk of aggressive disease.