title: Intensity analysis of Hartmann-Shack images in cataractous, keratoconic, and normal eyes to investigate light scattering.
abstract: OBJECTIVE
  A clinical investigation of novel methods for evaluating light scattering using a Hartmann-Shack aberrometer.
  
  
  METHODS
  Aberrometry was performed on normal eyes (n=7; patient age, 26.7+/-2.5 years, mean+/-SD), eyes with keratoconus (n=22; patient age, 26.1+/-8.1 years), and eyes with cataract (n=17; patient age, 56.5+/-16.9 years) using a Hartmann-Shack wavefront aberrometer. We introduced two methods: (1) a contrast method, in which we calculated the inverse of contrast of the local images around 12 spots in a Hartmann-Shack image, and (2) a difference of point spread function (PSF) method, in which we analyzed the difference between the width of the PSF computed with aberration information and the width of the measured PSF, which contains both aberration and light scattering information.
  
  
  RESULTS
  The inverse contrast in cataractous eyes (5.04+/-3.06 inverse contrast units) was significantly larger than that in normal eyes (1.57+/-0.56) or keratoconic eyes (1.83+/-0.79). The difference of PSF in cataractous eyes (81.8+/-65.2 microm) was also significantly larger than that in normal eyes (9.3+/-4.3 microm) or keratoconic eyes (30.0+/-20.1 microm). The inverse contrast and the difference in the PSF were highly correlated (r=0.89, P<0.0001).
  
  
  CONCLUSIONS
  The two methods introduced here successfully distinguished cataractous eyes from normal and keratoconic eyes. After the results were analyzed by a discriminant analysis, the separation of the three categories proved to be excellent.
authors.affiliation: Department of Visual Science, Osaka University Graduate School of Medicine, Osaka, Japan.|Technical Research Institute, Topcon Corporation, Tokyo, Japan.
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Mihashi
authors.affiliation: Department of Visual Science, Osaka University Graduate School of Medicine, Osaka, Japan.|Technical Research Institute, Topcon Corporation, Tokyo, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Hirohara
authors.affiliation: Department of Visual Science, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Bessho
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Maeda
authors.affiliation: Department of Ophthalmology, University of Tsukuba, Tsukuba, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Oshika
authors.affiliation: Department of Visual Science, Osaka University Graduate School of Medicine, Osaka, Japan. fujikado@ophthal.med.osaka-u.ac.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: Fujikado
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001251:Astigmatism / Q000175:diagnosis*; D002386:Cataract / Q000175:diagnosis*; D003315:Cornea / Q000473:pathology; D003941:Diagnostic Techniques, Ophthalmological; D006801:Humans; D007640:Keratoconus / Q000175:diagnosis*; D007908:Lens, Crystalline / Q000473:pathology; D008027:Light; D008875:Middle Aged; D012189:Retrospective Studies; D012542:Scattering, Radiation