title: Scatter and its implications for the measurement of optical image quality in human eyes.
abstract: OBJECTIVE
  To investigate the effect of scatter on measurements of wavefront aberrations and point-spread functions in a model eye.
  
  
  METHODS
  The wavefront aberrations of a model eye were measured using Hartmann-Shack wavefront sensing and crossed-cylinder aberroscope techniques and compared with its measured point-spread function in the presence of scattering media of different concentrations.
  
  
  RESULTS
  The point-spread functions became broader as the concentration increased. Forward light scatter on both the light path into the eye and the light path out of the eye contributed to this broadening of the point-spread function. Neither the crossed-cylinder aberroscope nor wavefront sensing, which, respectively, measure the ocular wavefront aberrations for light entering the eye and leaving the eye, were affected by the scatter.
  
  
  CONCLUSIONS
  We predict that by minimizing the contribution of the forward light scatter from one or other of these light paths by manipulating the size of the entrance and exit pupils, it should be possible to objectively assess narrow-angle forward light scatter in the eye by measuring and removing any confounding effect from wavefront aberration.
authors.affiliation: Department of Optometry, University of Bradford, Richmond Road, Bradford, West Yorkshire, United Kingdom. m.cox@bradford.ac.uk
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Cox
authors.forename: David A
authors.initials: DA
authors.lastname: Atchison
authors.forename: Dion H
authors.initials: DH
authors.lastname: Scott
mesh_terms: D003941:Diagnostic Techniques, Ophthalmological; D006801:Humans; D008027:Light; D008953:Models, Anatomic; D008954:Models, Biological; D012030:Refractive Errors / Q000503:physiopathology*; D012160:Retina / Q000503:physiopathology*; D012542:Scattering, Radiation; D014785:Vision, Ocular / Q000502:physiology*