title: Relationship between residual aberration and light-adapted pupil size.
abstract: OBJECTIVE
  The relationship between residual aberration (residual astigmatism and higher-order aberration) and light-adapted pupil size was investigated in human subjects to verify that the pupil size is adjusted to provide good image quality on the retina through control of the image sharpness and illuminance.
  
  
  METHODS
  Monochromatic wave aberration and light-adapted pupil diameters were measured from 20 subjects. The measured wave aberration was reconstructed using a sixth-order Zernike polynomial expansion; the neural sharpness was computed as a metric of the residual aberration. Subsequently, the correlation of the neural sharpness and the light-adapted pupil diameter was examined statistically across the subjects in each luminance level.
  
  
  RESULTS
  The light-adapted pupil diameter showed a significant positive correlation with the neural sharpness, except under dark-adapted conditions. In contrast, the pupil diameter showed no significant correlation with the spherical equivalent, as previously shown.
  
  
  CONCLUSIONS
  Our results suggest that the level of aberration present in an eye has an influence on pupil size.
authors.affiliation: Laboratory for Neuroinformatics, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan. sakai@brain.riken.jp
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sakai
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hirata
authors.forename: Shiro
authors.initials: S
authors.lastname: Usui
mesh_terms: D000221:Adaptation, Ocular / Q000502:physiology*; D000328:Adult; D001251:Astigmatism / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007498:Iris / Q000033:anatomy & histology* / Q000502:physiology; D008297:Male; D010775:Photic Stimulation; D011680:Pupil / Q000502:physiology*; D014792:Visual Acuity / Q000502:physiology