Accommodation with higher-order monochromatic aberrations corrected with adaptive optics.

Abstract

Higher-order monochromatic aberrations in the human eye cause a difference in the appearance of stimuli at distances nearer and farther from best focus that could serve as a signed error signal for accommodation. We explored whether higher-order monochromatic aberrations affect the accommodative response to 0.5 D step changes in vergence in experiments in which these aberrations were either present as they normally are or removed with adaptive optics. Of six subjects, one could not accommodate at all for steps in either condition. One subject clearly required higher-order aberrations to accommodate at all. The remaining four subjects could accommodate in the correct direction even when higher-order aberrations were removed. No subjects improved their accommodation when higher-order aberrations were corrected, indicating that the corresponding decrease in the depth of field of the eye did not improve the accommodative response. These results are consistent with previous findings of large individual differences in the ability to accommodate in impoverished conditions. These results suggest that at least some subjects can use monochromatic higher-order aberrations to guide accommodation. They also show that some subjects can accommodate correctly when higher-order monochromatic aberrations as well as established cues to accommodation are greatly reduced.