ABSTRACT
Clinical disorders of the eye (xerophthalmia) and ear represent responses of two different organ systems to systemic depletion of essential, pleiotropic vitamin A. Disruptions in both sensory systems were rst attributed to vitamin A deciency (VAD) in the early twentieth century1-3 but have coursed strikingly different historical paths in their clinical recognition, investigative pursuit, and public health attribution as VA deciency disorders. The contrast is evident in today’s knowledge of xerophthalmia as the world’s leading cause of preventable childhood blindness,4 with estimates of magnitude updated and monitored regularly by the World Health Organization (WHO),5 and hearing loss due to VAD remaining in experimental science and largely conjectured in human populations based on far fewer clinical and epidemiological reports6 and trials.7,8 Fortunately, both disorders are prevented, if to varied degrees, with adequate preschool VA prophylaxis. Not knowing the latter effect, however, may lead to an understated public health benet of preventing this deciency, especially in low-income countries.
