title: In Vivo Two-Photon Fluorescence Kinetics of Primate Rods and Cones.
abstract: OBJECTIVE
  The retinoid cycle maintains vision by regenerating bleached visual pigment through metabolic events, the kinetics of which have been difficult to characterize in vivo. Two-photon fluorescence excitation has been used previously to track autofluorescence directly from retinoids and pyridines in the visual cycle in mouse and frog retinas, but the mechanisms of the retinoid cycle are not well understood in primates.
  
  
  METHODS
  We developed a two-photon fluorescence adaptive optics scanning light ophthalmoscope dedicated to in vivo imaging in anesthetized macaques. Using pulsed light at 730 nm, two-photon fluorescence was captured from rods and cones during light and dark adaptation through the eye's pupil.
  
  
  RESULTS
  The fluorescence from rods and cones increased with light exposure but at different rates. During dark adaptation, autofluorescence declined, with cone autofluorescence decreasing approximately 4 times faster than from rods. Rates of autofluorescence decrease in rods and cones were approximately 4 times faster than their respective rates of photopigment regeneration. Also, subsets of sparsely distributed cones were less fluorescent than their neighbors immediately following bleach at 565 nm and they were comparable with the S cone mosaic in density and distribution.
  
  
  CONCLUSIONS
  Although other molecules could be contributing, we posit that these fluorescence changes are mediated by products of the retinoid cycle. In vivo two-photon ophthalmoscopy provides a way to monitor noninvasively stages of the retinoid cycle that were previously inaccessible in the living primate eye. This can be used to assess objectively photoreceptor function in normal and diseased retinas.
authors.affiliation: The Institute of Optics, University of Rochester, Rochester, New York, United States 2Center for Visual Science, University of Rochester, Rochester, New York, United States.
authors.forename: Robin
authors.initials: R
authors.lastname: Sharma
authors.affiliation: Center for Visual Science, University of Rochester, Rochester, New York, United States.
authors.forename: Christina
authors.initials: C
authors.lastname: Schwarz
authors.affiliation: The Institute of Optics, University of Rochester, Rochester, New York, United States 2Center for Visual Science, University of Rochester, Rochester, New York, United States 3Flaum Eye Institute, University of Rochester, Rochester, New York, United States.
authors.forename: David R
authors.initials: DR
authors.lastname: Williams
authors.affiliation: Polgenix, Inc., Cleveland, Ohio, United States.
authors.forename: Grazyna
authors.initials: G
authors.lastname: Palczewska
authors.affiliation: Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Palczewski
authors.affiliation: Center for Visual Science, University of Rochester, Rochester, New York, United States 3Flaum Eye Institute, University of Rochester, Rochester, New York, United States.
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Hunter
mesh_terms: D000818:Animals; D003623:Dark Adaptation; D005260:Female; D008252:Macaca fascicularis; D008253:Macaca mulatta; D008297:Male; D009887:Ophthalmoscopy; D061848:Optical Imaging / Q000379:methods*; D017949:Retinal Cone Photoreceptor Cells / Q000166:cytology / Q000502:physiology*; D017948:Retinal Rod Photoreceptor Cells / Q000166:cytology / Q000502:physiology*