title: Henle fiber layer phase retardation changes associated with age-related macular degeneration.
abstract: OBJECTIVE
  To quantify and compare phase retardation amplitude and regularity associated with the Henle fiber layer (HFL) between nonexudative AMD patients and age-matched controls using scanning laser polarimetry (SLP) imaging.
  
  
  METHODS
  A scanning laser polarimeter was used to collect 15 × 15° macular-centered images in 25 patients with nonexudative AMD and 25 age-matched controls. Raw image data were used to compute macular phase retardation maps associated with the HFL. Consecutive, annular regions of interest from 0.5 to 3.0° eccentricity, centered on the fovea, were used to generate intensity profiles from phase retardation data and analyzed with two complementary techniques: a normalized second harmonic frequency (2f) of the fast Fourier Transform (FFT) analysis and a curve fitting analysis using a 2f sine function. Paired t-tests were used to compare the normalized 2f FFT magnitude at each eccentricity between the two groups, the eccentricity that yielded the maximum normalized 2f FFT between paired individuals across the two groups, and curve fitting RMS error at each eccentricity between the two groups.
  
  
  RESULTS
  Normalized 2f FFT components were lower in the AMD group at each eccentricity, with no difference between the two groups in the maximum normalized 2f FFT component eccentricity. The root-mean-square (RMS) error from curve fitting was significantly higher in the AMD group.
  
  
  CONCLUSIONS
  Phase retardation changes in the central macula indicate loss and/or structural alterations to central cone photoreceptors in nonexudative AMD patients. Scanning laser polarimetry imaging is a noninvasive method for quantifying cone photoreceptor changes associated with central macular disease.
authors.affiliation: The Ohio State University College of Optometry, Columbus, Ohio, United States.
authors.forename: Dean A
authors.initials: DA
authors.lastname: VanNasdale
authors.affiliation: Indiana University School of Optometry, Bloomington, Indiana, United States.
authors.forename: Ann E
authors.initials: AE
authors.lastname: Elsner
authors.affiliation: Indiana University School of Optometry, Bloomington, Indiana, United States.
authors.forename: Todd D
authors.initials: TD
authors.lastname: Peabody
authors.affiliation: Indiana University School of Optometry, Bloomington, Indiana, United States.
authors.forename: Kimberly D
authors.initials: KD
authors.lastname: Kohne
authors.affiliation: Indiana University School of Optometry, Bloomington, Indiana, United States.
authors.forename: Victor E
authors.initials: VE
authors.lastname: Malinovsky
authors.affiliation: Indiana University School of Optometry, Bloomington, Indiana, United States.
authors.forename: Bryan P
authors.initials: BP
authors.lastname: Haggerty
authors.affiliation: Aachen University Hospital, Aachen, Germany.
authors.forename: Anke
authors.initials: A
authors.lastname: Weber
authors.affiliation: Indiana University School of Optometry, Bloomington, Indiana, United States.
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Clark
authors.affiliation: Indiana University School of Optometry, Bloomington, Indiana, United States.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Burns
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008266:Macula Lutea / Q000473:pathology*; D008268:Macular Degeneration / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D017949:Retinal Cone Photoreceptor Cells / Q000473:pathology*; D012165:Retinal Ganglion Cells / Q000473:pathology*; D057109:Scanning Laser Polarimetry
keywords: Henle fiber layer; age-related macular degeneration; photoreceptors; scanning laser polarimetry