title: Improved visualization of Henle fiber layer by changing the measurement beam angle on optical coherence tomography.
abstract: OBJECTIVE
  The outer plexiform layer (OPL) includes the photoreceptor synapse layer and Henle fiber layer (HFL) in the macular area. We attempted to improve optical coherence tomography imaging of the HFL by changing the angle of the measurement beam.
  
  
  METHODS
  Thirteen normal eyes underwent spectral domain optical coherence tomography. To focus the angle of the measurement beam perpendicular to the obliquely oriented HFL, the beam in the optical coherence tomography system was aimed at the periphery of the pupil.
  
  
  RESULTS
  The cross-sectional image of the macular area was inclined right or left if the beam entered from the periphery of the pupil. The reflectivity of the OPL increased because of strong backscattering of light in the half of the macula that was tilted down in cross-sectional images. On the opposite side, the reflectivity of HFL (the outer two-thirds of the OPL) decreased compared with that of the outer nuclear layer, but the photoreceptor synapse layer (the inner one-third of the OPL) remained highly reflective. The mean thicknesses of the OPL that could be visualized 1.0 mm and 1.5 mm from the central fovea were 73.7 ± 7.0 μm and 64.1 ± 8.2 μm, respectively.
  
  
  CONCLUSIONS
  Positioning the measurement beam perpendicular to HFL enhanced visualization performance.
authors.affiliation: Department of Ophthalmology, Gunma University School of Medicine, Maebashi, Gunma, Japan. otanito@showa.gunma-u.ac.jp
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Otani
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Yamaguchi
authors.forename: Shoji
authors.initials: S
authors.lastname: Kishi
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005584:Fovea Centralis / Q000033:anatomy & histology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D020419:Photoreceptor Cells, Vertebrate / Q000166:cytology*; D017729:Presynaptic Terminals; D012165:Retinal Ganglion Cells / Q000166:cytology*; D041623:Tomography, Optical Coherence