title: Noninvasive imaging of human foveal capillary network using dual-conjugate adaptive optics.
abstract: OBJECTIVE
  To demonstrate noninvasive imaging of human foveal capillary networks with a high-resolution, wide-field, dual-conjugate adaptive optics (DCAO) imaging instrument.
  
  
  METHODS
  The foveal capillary networks of five healthy subjects with no previous history of ocular or neurologic disease or surgery were imaged with a novel high-resolution, wide-field DCAO instrument. The foveal avascular zone (FAZ) in each image was defined using a manual procedure. An automated algorithm based on publicly available and custom-written software was used to identify vessels and extract morphologic FAZ and vessel parameters. Capillary densities were calculated in two annular regions of interest (ROIs) outside the FAZ (500 μm and 750 μm outer radius from the foveal center) and in the superior, inferior, temporal, and nasal quadrants within the two ROIs.
  
  
  RESULTS
  Mean FAZ area was 0.302 ± 0.100 mm(2), and mean capillary density (length/area) in the inner ROI was 38.0 ± 4.0 mm(-1) and 36.4 ± 4.0 mm(-1) in the outer ROI. The difference in ROI capillary density was not significant. There was no significant difference in quadrant capillary density within the two ROIs or between quadrants irrespective of ROI.
  
  
  CONCLUSIONS
  The authors have demonstrated a technique for noninvasive imaging and semiautomated detection and analysis of foveal capillaries. In comparison with other studies, their method yielded lower capillary densities than histology but similar results to the current clinical gold standard, fluorescein angiography. The increased field of view of the DCAO instrument opens up new possibilities for high-resolution noninvasive clinical imaging of foveal capillaries.
authors.affiliation: Department of Ophthalmology, University of Gothenburg, Gothenburg, Sweden. zoran@oft.gu.se
authors.forename: Zoran
authors.initials: Z
authors.lastname: Popovic
authors.forename: Per
authors.initials: P
authors.lastname: Knutsson
authors.forename: Jörgen
authors.initials: J
authors.lastname: Thaung
authors.forename: Mette
authors.initials: M
authors.lastname: Owner-Petersen
authors.forename: Johan
authors.initials: J
authors.lastname: Sjöstrand
mesh_terms: D000328:Adult; D002196:Capillaries / Q000033:anatomy & histology; D003952:Diagnostic Imaging / Q000295:instrumentation*; D003941:Diagnostic Techniques, Ophthalmological; D005584:Fovea Centralis / Q000098:blood supply*; D006801:Humans; D008875:Middle Aged; D055095:Optics and Photonics / Q000295:instrumentation; D012171:Retinal Vessels / Q000033:anatomy & histology*