Retinal changes produced by phototherapy

This study was undertaken to assess the effect of blue fluorescent light on retinas of a pigmented, diurnal animal, the newborn piglet. The animals, having one eye shielded, were placed under a phototherapy unit as used for newborn infants. Three weeks after exposure, under light microscopy, the tissues of eyes exposed for 72 hours, and in one instance for slightly less than 12 hours, showed marked damage to the photoreceptors (rods and cones). Under electron microscopy, changes in the visual receptors were observed in the exposed eyes which were not observed in the shielded eyes. High-intensity blue fluorescent light was shown to damage the retinas of newborn piglets, developmentally similar to those of human infants. Therefore, utmost care would seem to be required to shield the eyes of infants exposed to bilirubin phototherapy units.