Influence of edge sharpness on the accommodation of the human eye.

Using a subjective method of laser refractometry, the accommodation behavior of six subjects toward real targets with various degrees of blur, dependent on the viewing distance, were investigated monocularly and binocularly. Despite the sharpness of the target, the nominal value is only reached incompletely with a lag of accommodation, because accommodation tends to be as minimal as possible. Increasing blurring leads to a drift of accommodation towards the resting position of accommodation. The resulting underaccommodation causes further physiological blurring of the retinal image of the targets. The approach of the targets to the resting position of accommodation leads to a higher precision of adjustment and less drift. Subjective components (accommodative laziness, cognitive demand) influence the accommodation and increase the phenomenons discovered.