title: Cone photoreceptor definition on adaptive optics retinal imaging.
abstract: OBJECTIVE
  To quantitatively analyse cone photoreceptor matrices on images captured on an adaptive optics (AO) camera and assess their correlation to well-established parameters in the retinal histology literature.
  
  
  METHODS
  High resolution retinal images were acquired from 10 healthy subjects, aged 20-35 years old, using an AO camera (rtx1, Imagine Eyes, France). Left eye images were captured at 5° of retinal eccentricity, temporal to the fovea for consistency. In three subjects, images were also acquired at 0, 2, 3, 5 and 7° retinal eccentricities. Cone photoreceptor density was calculated following manual and automated counting. Inter-photoreceptor distance was also calculated. Voronoi domain and power spectrum analyses were performed for all images.
  
  
  RESULTS
  At 5° eccentricity, the cone density (cones/mm(2) mean±SD) was 15.3±1.4×10(3) (automated) and 13.9±1.0×10(3) (manual) and the mean inter-photoreceptor distance was 8.6±0.4 μm. Cone density decreased and inter-photoreceptor distance increased with increasing retinal eccentricity from 2 to 7°. A regular hexagonal cone photoreceptor mosaic pattern was seen at 2, 3 and 5° of retinal eccentricity.
  
  
  CONCLUSIONS
  Imaging data acquired from the AO camera match cone density, intercone distance and show the known features of cone photoreceptor distribution in the pericentral retina as reported by histology, namely, decreasing density values from 2 to 7° of eccentricity and the hexagonal packing arrangement. This confirms that AO flood imaging provides reliable estimates of pericentral cone photoreceptor distribution in normal subjects.
authors.affiliation: National Institute for Health Research, Biomedical Research Centre for Ophthalmology, London, UK Moorfields Eye Hospital, London, UK Division of Cellular Therapy, UCL Institute of Ophthalmology, London, UK.
authors.forename: Manickam Nick
authors.initials: MN
authors.lastname: Muthiah
authors.affiliation: Division of Cellular Therapy, UCL Institute of Ophthalmology, London, UK.
authors.forename: Carlos
authors.initials: C
authors.lastname: Gias
authors.affiliation: Centre for Ophthalmology and Visual Science (incorporating Lions Eye Institute), The University of Western Australia, Perth, Australia.
authors.forename: Fred Kuanfu
authors.initials: FK
authors.lastname: Chen
authors.affiliation: Moorfields Eye Hospital, London, UK.
authors.forename: Joe
authors.initials: J
authors.lastname: Zhong
authors.affiliation: Moorfields Eye Hospital, London, UK.
authors.forename: Zoe
authors.initials: Z
authors.lastname: McClelland
authors.affiliation: Department of Research and Development, The Reading Centre, Moorfields Eye Hospital, London, UK.
authors.forename: Ferenc B
authors.initials: FB
authors.lastname: Sallo
authors.affiliation: National Institute for Health Research, Biomedical Research Centre for Ophthalmology, London, UK Department of Research and Development, The Reading Centre, Moorfields Eye Hospital, London, UK.
authors.forename: Tunde
authors.initials: T
authors.lastname: Peto
authors.affiliation: Division of Cellular Therapy, UCL Institute of Ophthalmology, London, UK.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Coffey
authors.affiliation: National Institute for Health Research, Biomedical Research Centre for Ophthalmology, London, UK Moorfields Eye Hospital, London, UK Division of Cellular Therapy, UCL Institute of Ophthalmology, London, UK.
authors.forename: Lyndon
authors.initials: L
authors.lastname: da Cruz
mesh_terms: D000328:Adult; D002452:Cell Count; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D009887:Ophthalmoscopy / Q000379:methods; D055095:Optics and Photonics / Q000379:methods*; D010781:Photography / Q000379:methods*; D012160:Retina / Q000033:anatomy & histology*; D017949:Retinal Cone Photoreceptor Cells / Q000166:cytology*; D014794:Visual Fields / Q000502:physiology; D055815:Young Adult
keywords: Adaptive Optics; Cone Photoreceptor; Retinal Imaging
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