title: Techniques for extraction of depth-resolved in vivo human retinal intrinsic optical signals with optical coherence tomography.
abstract: OBJECTIVE
  To demonstrate acquisition and analysis methods for depth-resolved observation of slow retinal physiology induced changes in infrared backscatter in vivo.
  
  
  METHODS
  A dark-adapted human was briefly subjected to a localized photobleach. For 20 min before and 30 min after the stimulus, volumetric optical coherence tomograms were collected partially overlapping the bleached region. Tomograms were segmented into retinal layers by a newly described algorithm exploiting information in adjacent B-scans. En face fundus images extracted from major intraretinal layers were laterally registered manually. Time series summarizing the observed backscatter in selected layers for the bleached and unbleached areas are shown with a variety of corrections and normalizations applied: tomograms were corrected for inherent sensitivity roll-off, and the ratio between other layers and an assumed unchanging layer (retinal pigment epithelium), as well as the ratio of the stimulated area to the unstimulated area, were calculated.
  
  
  RESULTS
  Adjacent B-scan information allows a simpler segmentation algorithm to be used. Sensitivity roll-off correction reduces signal variability due to eye motion. After normalizations, the signal correlated with the stimulus appears strongest at the photoreceptor inner-outer segment junction.
  
  
  CONCLUSIONS
  Demonstrated methods manage data complexity and reduce uncorrelated signal variability. This single trial warrants further investigation of intrinsic optical signals to observe slow physiologic responses.
authors.affiliation: Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff CF24 4LU, Wales, UK.
authors.forename: Alexandre R
authors.initials: AR
authors.lastname: Tumlinson
authors.forename: Boris
authors.initials: B
authors.lastname: Hermann
authors.forename: Bernd
authors.initials: B
authors.lastname: Hofer
authors.forename: Boris
authors.initials: B
authors.lastname: Povazay
authors.forename: Tom H
authors.initials: TH
authors.lastname: Margrain
authors.forename: Alison M
authors.initials: AM
authors.lastname: Binns
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Drexler
mesh_terms: D003623:Dark Adaptation / Q000502:physiology; D006801:Humans; D010775:Photic Stimulation; D012160:Retina / Q000502:physiology*; D041623:Tomography, Optical Coherence / Q000379:methods*