title: Fourier analysis of nerve fiber layer measurements from scanning laser polarimetry in glaucoma: emphasizing shape characteristics of the 'double-hump' pattern.
abstract: OBJECTIVE
  The pattern of the distribution of nerve fiber layer (NFL) thickness values across the retina may provide an early anatomic indication of glaucomatous disruption. We developed a method of analyzing polarimetry measurements that emphasizes the shape of the pattern of NFL thickness values. Sensitivity and specificity for detecting glaucoma was obtained for these measures and compared with those for conventional measures.
  
  
  METHODS
  Nerve fiber thickness was inferred from retardation shift measured by a scanning laser polarimeter (Laser Diagnostic Technologies, Inc., San Diego, CA) in 34 healthy subjects (68 eyes) and 34 patients with glaucoma (68 eyes). Fourier analysis was performed on the polarimetry data to emphasize the shape in the evaluation of the distribution of thickness values around the optic disc (along a 1.7-disc diameter ring). This was computed separately on superior and inferior hemiretinas.
  
  
  RESULTS
  Significant differences were found in the Fourier shape measures between healthy subjects and patients with glaucoma. The sensitivity and specificity using Fourier coefficients with this particular sample was 96% and 90%, respectively.
  
  
  CONCLUSIONS
  The evaluation of NFL measurements with Fourier analysis to emphasize the holistic shape of the "double-hump" pattern was found to be a useful tool as an analysis strategy.
authors.affiliation: Department of Psychological and Brain Science, University of Louisville, Kentucky 40292, USA.
authors.forename: E A
authors.initials: EA
authors.lastname: Essock
authors.forename: M J
authors.initials: MJ
authors.lastname: Sinai
authors.forename: R D
authors.initials: RD
authors.lastname: Fechtner
authors.forename: N
authors.initials: N
authors.lastname: Srinivasan
authors.forename: F D
authors.initials: FD
authors.lastname: Bryant
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001369:Axons / Q000473:pathology; D005583:Fourier Analysis; D005902:Glaucoma, Open-Angle / Q000175:diagnosis*; D006801:Humans; D007368:Interferometry; D007834:Lasers; D008027:Light; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D009900:Optic Nerve / Q000473:pathology*; D012372:ROC Curve; D012165:Retinal Ganglion Cells / Q000473:pathology*; D012680:Sensitivity and Specificity; D058609:Visual Field Tests / Q000379:methods*