title: In Vivo Imaging of the Human Retinal Pigment Epithelial Mosaic Using Adaptive Optics Enhanced Indocyanine Green Ophthalmoscopy.
abstract: OBJECTIVE
  The purpose of this study was to establish that retinal pigment epithelial (RPE) cells take up indocyanine green (ICG) dye following systemic injection and that adaptive optics enhanced indocyanine green ophthalmoscopy (AO-ICG) enables direct visualization of the RPE mosaic in the living human eye.
  
  
  METHODS
  A customized adaptive optics scanning light ophthalmoscope (AOSLO) was used to acquire high-resolution retinal fluorescence images of residual ICG dye in human subjects after intravenous injection at the standard clinical dose. Simultaneously, multimodal AOSLO images were also acquired, which included confocal reflectance, nonconfocal split detection, and darkfield. Imaging was performed in 6 eyes of three healthy subjects with no history of ocular or systemic diseases. In addition, histologic studies in mice were carried out.
  
  
  RESULTS
  The AO-ICG channel successfully resolved individual RPE cells in human subjects at various time points, including 20 minutes and 2 hours after dye administration. Adaptive optics-ICG images of RPE revealed detail which could be correlated with AO dark-field images of the same cells. Interestingly, there was a marked heterogeneity in the fluorescence of individual RPE cells. Confirmatory histologic studies in mice corroborated the specific uptake of ICG by the RPE layer at a late time point after systemic ICG injection.
  
  
  CONCLUSIONS
  Adaptive optics-enhanced imaging of ICG dye provides a novel way to visualize and assess the RPE mosaic in the living human eye alongside images of the overlying photoreceptors and other cells.
authors: Ophthalmic Genetics and Visual Function Branch National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States.
authors: Johnny
authors: J
authors: Tam
authors: Ophthalmic Genetics and Visual Function Branch National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States.
authors: Jianfei
authors: J
authors: Liu
authors: Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States 3Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin, United States 4Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States.
authors: Alfredo
authors: A
authors: Dubra
authors: Biological Imaging Core, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States.
authors: Robert
authors: R
authors: Fariss
mesh_terms: D000328:Adult; D000818:Animals; D004396:Coloring Agents / Q000494:pharmacology; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007208:Indocyanine Green / Q000494:pharmacology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009887:Ophthalmoscopy / Q000379:methods; D055095:Optics and Photonics; D055213:Retinal Pigment Epithelium / Q000166:cytology*
chemical_list: D004396:Coloring Agents; D007208:Indocyanine Green