title: Reliability of cone counts using an adaptive optics retinal camera.
abstract: BACKGROUND
  To assess the reproducibility and repeatability of cone imaging in healthy human eyes, using the RTx-1 Adaptive Optics Retinal Camera and its proprietary cone-counting software.
  
  
  METHODS
  Single-centre, prospective study.
  
  
  METHODS
  Ten healthy adults.
  
  
  METHODS
  Macular cones were imaged. Intrasession repeatability was assessed by comparing 10 consecutive acquisitions obtained by the same operator from each subject. For the intersession study, each subject was imaged five consecutive days. Interoperator reproducibility was also evaluated by comparing the images obtained from 10 different subjects by two independent operators. Finally, intergrader agreement was evaluated by comparing the cone counts measured by two masked graders.
  
  
  METHODS
  Mean cone density (cells/mm(2) ), spacing between cells (μm) and percentage of cones with six neighbours calculated on Voronoi diagrams were measured. Correlation coefficients, intraclass correlation coefficients, and coefficients of variation were calculated.
  
  
  RESULTS
  Correlation coefficient and intraclass correlation coefficient were respectively 0.81 and 0.96 between operators, and 0.97 and 0.98 between the two graders. The intrasession and intersession coefficients of variation were under 7%. The percentage of cells with six neighbours and the spacing between cones varied in the same proportion (coefficients of variation ranged from 1.66 to 10.05%).
  
  
  CONCLUSIONS
  Overall, the test-retest variability of RTx-1 and its software was good in normal human eyes. Further studies in the normal clinical setting are mandatory.
authors.affiliation: Department of Ophthalmology, University Hospital of Besançon, University of Franche-Comté, Besançon, France.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Bidaut Garnier
authors.forename: Mathieu
authors.initials: M
authors.lastname: Flores
authors.forename: Guillaume
authors.initials: G
authors.lastname: Debellemanière
authors.forename: Marc
authors.initials: M
authors.lastname: Puyraveau
authors.forename: Perle
authors.initials: P
authors.lastname: Tumahai
authors.forename: Mathieu
authors.initials: M
authors.lastname: Meillat
authors.forename: Claire
authors.initials: C
authors.lastname: Schwartz
authors.forename: Michel
authors.initials: M
authors.lastname: Montard
authors.forename: Bernard
authors.initials: B
authors.lastname: Delbosc
authors.forename: Maher
authors.initials: M
authors.lastname: Saleh
mesh_terms: D000328:Adult; D002452:Cell Count; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D015588:Observer Variation; D061848:Optical Imaging / Q000295:instrumentation*; D010781:Photography / Q000379:methods*; D011446:Prospective Studies; D015203:Reproducibility of Results; D017949:Retinal Cone Photoreceptor Cells / Q000166:cytology*; D014792:Visual Acuity
keywords: cell count; healthy volunteers; optical imaging; reproducibility of results; retinal cone photoreceptor cells