The role of accommodation in increasing the luminance of the fundus reflex during cognitive processing.

The phenomena observed during book retinoscopy include changes in the brightness of the reflex in response to changes in cognition. This experiment shows that the increase in luminance of the relfex that results from increased cognitive demand is mediated by accommodation. The luminance of the fundus reflex was monitored while subjects either read or added a series of two-digit numbers. During the addition task the luminance of the reflex increased in all cases. However, under cycloplegia the increase in luminance could not be predicted.