title: Representing the retinal line spread shape with mathematical functions.
abstract: OBJECTIVE
  To report a mathematical function that characterizes the double-pass line spread function (LSF) of the human eye. Determining analytical functions that represent the double-pass LSF is important because it allows modeling the optical performance of the eye.
  
  
  METHODS
  Optical section retinal images, generated in normal human eyes using a modified slit-lamp biomicroscope, were analyzed to derive the double-pass LSF by plotting the intensity distribution of laser light reflected/ scattered from the vitreoretinal interface. Three mathematical functions (Lorentzian, Gaussian, exponential) were fitted to the double-pass LSF and the root mean square error (RMSE) was calculated to provide a measure of the goodness of fit.
  
  
  RESULTS
  The Lorentzian function provided the best representation of the double-pass LSF of normal human eyes. The full width at half maximum (FWHM) of the Lorentzian fitted curve was positively correlated with age, indicating that the double-pass LSF broadens with age. Furthermore, the goodness of fit of the Lorentzian function was significantly better in younger subjects as compared with older subjects, suggesting that the fitted function to the double-pass LSF may vary according to age.
  
  
  CONCLUSIONS
  The results demonstrate an age-related change in the double-pass LSF width and the goodness of fit of the Lorentzian function.
authors.affiliation: Department of Bioengineering, University of Illinois at Chicago, IL 60607, USA. yyang19@uic.edu
authors.forename: Yi-Rong
authors.initials: YR
authors.lastname: Yang
authors.forename: Justin
authors.initials: J
authors.lastname: Wanek
authors.forename: Mahnaz
authors.initials: M
authors.lastname: Shahidi
mesh_terms: D000328:Adult; D000368:Aged; D006801:Humans; D008433:Mathematics; D008875:Middle Aged; D012160:Retina / Q000502:physiology*; D014785:Vision, Ocular / Q000502:physiology*