title: Effect of Uveal Melanocytes on Choroidal Morphology in Rhesus Macaques and Humans on Enhanced-Depth Imaging Optical Coherence Tomography.
abstract: OBJECTIVE
  To compare cross-sectional choroidal morphology in rhesus macaque and human eyes using enhanced-depth imaging optical coherence tomography (EDI-OCT) and histologic analysis.
  
  
  METHODS
  Enhanced-depth imaging-OCT images from 25 rhesus macaque and 30 human eyes were evaluated for choriocapillaris and choroidal-scleral junction (CSJ) visibility in the central macula based on OCT reflectivity profiles, and compared with age-matched histologic sections. Semiautomated segmentation of the choriocapillaris and CSJ was used to measure choriocapillary and choroidal thickness, respectively. Multivariate regression was performed to determine the association of age, refractive error, and race with choriocapillaris and CSJ visibility.
  
  
  RESULTS
  Rhesus macaques exhibit a distinct hyporeflective choriocapillaris layer on EDI-OCT, while the CSJ cannot be visualized. In contrast, humans show variable reflectivities of the choriocapillaris, with a distinct CSJ seen in many subjects. Histologic sections demonstrate large, darkly pigmented melanocytes that are densely distributed in the macaque choroid, while melanocytes in humans are smaller, less pigmented, and variably distributed. Optical coherence tomography reflectivity patterns of the choroid appear to correspond to the density, size, and pigmentation of choroidal melanocytes. Mean choriocapillary thickness was similar between the two species (19.3 ± 3.4 vs. 19.8 ± 3.4 μm, P = 0.615), but choroidal thickness may be lower in macaques than in humans (191.2 ± 43.0 vs. 266.8 ± 78.0 μm, P < 0.001). Racial differences in uveal pigmentation also appear to affect the visibility of the choriocapillaris and CSJ on EDI-OCT.
  
  
  CONCLUSIONS
  Pigmented uveal melanocytes affect choroidal morphology on EDI-OCT in rhesus macaque and human eyes. Racial differences in pigmentation may affect choriocapillaris and CSJ visibility, and may influence the accuracy of choroidal thickness measurements.
authors: Department of Ophthalmology and Vision Science, University of California-Davis, Sacramento, California, United States.
authors: Glenn
authors: G
authors: Yiu
authors: Department of Ophthalmology and Vision Science, University of California-Davis, Sacramento, California, United States.
authors: Vivian S
authors: VS
authors: Vuong
authors: Department of Ophthalmology and Vision Science, University of California-Davis, Sacramento, California, United States.
authors: Sharon
authors: S
authors: Oltjen
authors: Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States.
authors: David
authors: D
authors: Cunefare
authors: Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States.
authors: Sina
authors: S
authors: Farsiu
authors: California National Primate Research Center, Davis, California, United States.
authors: Laura
authors: L
authors: Garzel
authors: California National Primate Research Center, Davis, California, United States 4Department of Medicine and Epidemiology, University of California-Davis, School of Veterinary Medicine, Davis, California, United States.
authors: Jeffrey
authors: J
authors: Roberts
authors: Department of Surgical and Radiological Sciences, University of California-Davis, School of Veterinary Medicine, Davis, California, United States.
authors: Sara M
authors: SM
authors: Thomasy
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D002829:Choroid / Q000473:pathology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007089:Image Enhancement; D008253:Macaca mulatta; D008297:Male; D008544:Melanocytes / Q000473:pathology*; D008545:Melanoma / Q000175:diagnosis*; D008875:Middle Aged; D009374:Neoplasms, Experimental; D015203:Reproducibility of Results; D041623:Tomography, Optical Coherence / Q000379:methods*; D014604:Uveal Neoplasms / Q000175:diagnosis*; D000098943:Uveal Melanoma