Preventing blindness and saving lives: the centenary of vitamin A.

Within 20 years of its discovery 100 years ago, vitamin A was recognized as critical to normal eyes, growth, and survival. Clinical interest subsequently contracted to its importance in preventing xerophthalmia, until this ophthalmologist stumbled, quite accidently, on its role in fighting life-threatening infections. Repeated, large-scale randomized clinical trials eventually convinced (and reminded) the pediatric and nutrition communities of its importance for child survival. Vitamin A distribution programs are now credited with saving the sight and lives of nearly half a million children every year.