title: A Monte Carlo Analysis of Error Associated With Two-Wavelength Algorithms for Retinal Oximetry.
abstract: Two-wavelength algorithms aimed at the extrapolation of retinal vasculature optical properties are being used in the clinical setting. Although robust, this approach has some clear mathematical limitations. We have conducted an in-depth study of this methodology and report on the limits and benefit of this approach.
  
  
  
  We used a well-tested, voxel-based Monte Carlo model of light transfer into biological tissue combined with a seven-layer model of the human fundus to create reflectance maps of retina vessels at different oxygenation levels.
  
  
  
  This study shows that the two-wavelength approach works remarkably well in the optimal scenario of known calibration arteries and veins. Errors as a result of choroidal pigmentation and discrepancies in vessel size can be minimized with numerical approaches. When the calibration process deviates largely from physiological values, the technique fails with large errors.
  
  
  
  The two-wavelength approach is convenient, easy to implement, and suitable in studies where relative rather than absolute knowledge of retinal oximetry is necessary. A robust calibration step is paramount when using this approach.
authors.affiliation: Department of Biomedical Engineering, Florida International University, Miami, Florida, United States.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Rodriguez
authors.affiliation: Food and Drug Administration, Center for Devices and Radiological Health, Silver Spring, Maryland, United States.
authors.forename: T Joshua
authors.initials: TJ
authors.lastname: Pfefer
authors.affiliation: Food and Drug Administration, Center for Devices and Radiological Health, Silver Spring, Maryland, United States.
authors.forename: Quanzeng
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, United States.
authors.forename: Pedro F
authors.initials: PF
authors.lastname: Lopez
authors.affiliation: Department of Biomedical Engineering, Florida International University, Miami, Florida, United States 3Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, United States.
authors.forename: Jessica C
authors.initials: JC
authors.lastname: Ramella-Roman
mesh_terms: D000465:Algorithms; D002138:Calibration; D006801:Humans; D008962:Models, Theoretical; D009010:Monte Carlo Method; D010092:Oximetry / Q000379:methods*; D010100:Oxygen / Q000378:metabolism*; D015203:Reproducibility of Results; D012171:Retinal Vessels / Q000502:physiology*
chemical_list: D010100:Oxygen