title: Differences between wavefront and subjective refraction for infrared light.
abstract: OBJECTIVE
  To determine the accuracy of objective wavefront refractions for predicting subjective refractions for monochromatic infrared light.
  
  
  METHODS
  Objective refractions were obtained with a commercial wavefront aberrometer (COAS, Wavefront Sciences). Subjective refractions were obtained for 30 subjects with a speckle optometer validated against objective Zernike wavefront refractions on a physical model eye (Teel et al., Design and validation of an infrared Badal optometer for laser speckle, Optom Vis Sci 2008;85:834-42). Both instruments used near-infrared (NIR) radiation (835 nm for COAS, 820 nm for the speckle optometer) to avoid correction for ocular chromatic aberration. A 3-mm artificial pupil was used to reduce complications attributed to higher-order ocular aberrations. For comparison with paraxial (Seidel) and minimum root-mean-square (Zernike) wavefront refractions, objective refractions were also determined for a battery of 29 image quality metrics by computing the correcting lens that optimizes retinal image quality.
  
  
  RESULTS
  Objective Zernike refractions were more myopic than subjective refractions for 29 of 30 subjects. The population mean discrepancy was -0.26 diopters (D) (SEM = 0.03 D). Paraxial (Seidel) objective refractions tended to be hyperopically biased (mean discrepancy = +0.20 D, SEM = 0.06 D). Refractions based on retinal image quality were myopically biased for 28 of 29 metrics. The mean bias across all 31 measures was -0.24 D (SEM = 0.03). Myopic bias of objective refractions was greater for eyes with brown irises compared with eyes with blue irises.
  
  
  CONCLUSIONS
  Our experimental results are consistent with the hypothesis that reflected NIR light captured by the aberrometer originates from scattering sources located posterior to the entrance apertures of cone photoreceptors, near the retinal pigment epithelium. The larger myopic bias for brown eyes suggests that a greater fraction of NIR light is reflected from choroidal melanin in brown eyes compared with blue eyes.
authors.affiliation: *OD, PhD, FAAO †MSc(Optom), PhD, FAAO ‡BS §PhD ∥PhD, FAAO Indiana University School of Optometry, Bloomington, Indiana (DFWT, LNT); Department of Optometry, University of Auckland, Auckland, New Zealand (RJJ); and Wavefront Sciences, Inc, Albuquerque, New Mexico (JC, DRN).
authors.forename: Danielle F W
authors.initials: DF
authors.lastname: Teel
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Jacobs
authors.forename: James
authors.initials: J
authors.lastname: Copland
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Neal
authors.forename: Larry N
authors.initials: LN
authors.lastname: Thibos
mesh_terms: D057128:Aberrometry; D000328:Adult; D000465:Algorithms; D057108:Corneal Wavefront Aberration / Q000503:physiopathology*; D005127:Eye Color / Q000502:physiology; D005260:Female; D006801:Humans; D007259:Infrared Rays; D008027:Light; D008297:Male; D008875:Middle Aged; D012029:Refraction, Ocular / Q000502:physiology*; D012030:Refractive Errors / Q000503:physiopathology*; D012542:Scattering, Radiation; D055815:Young Adult