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November 1993

A Randomized Trial of Vitamin A and Vitamin E Supplementation for Retinitis Pigmentosa-Reply

Author Affiliations

Boston, Mass

Arch Ophthalmol. 1993;111(11):1463-1465. doi:10.1001/archopht.1993.01090110018008

In reply  We are pleased by the interest generated by our article1 in the June 1993 issue of the Archives and welcome the opportunity to reply.In response to Drs Fielder and Marshall, the ERG is an indicator of visual function in RP for the reasons enumerated in our response to the editorial by Drs Massof and Finkelstein.2 Thus, we cannot accept their statement that our publication raises "false hopes." Instead, vitamin A therapy should be accepted for what the data show—a means to slow, in modest degree, the mean rate of decline of remaining retinal function for adults afflicted with RP.Dr Norton's comments emphasize individual group comparisons while ignoring the factorial design of the study. The factorial study design has been widely used in major clinical trials sponsored by the National Institutes of Health to evaluate two treatment effects in one study with the smallest possible sample