Pupillary Size and Light Reflex in Premature Infants

The authors examined pupillary light reflexes to both red and blue stimuli using infrared video-pupillography in premature infants. Pupillary light reflexes were obtained in response to 470 nm blue and 635 nm red stimuli with varying intensities of 10 cd/m² and 100 cd/m². Red stimuli did not evoke a pupillary response in premature infants. However, blue stimuli produced a pupillary reflex, and the extent of the reaction was dependent on the intensity of the stimulus. These results suggest that in premature infants, the origin of light reflex may be mediated predominately by melanopsin-containing retinal ganglion cells.