title: Choriocapillaris Flow Features Follow a Power Law Distribution: Implications for Characterization and Mechanisms of Disease Progression.
abstract: OBJECTIVE
  To investigate flow characteristics of the choriocapillaris using optical coherence tomography angiography.
  
  
  METHODS
  Retrospective observational case series.
  
  
  METHODS
  Visualization of flow in individual choriocapillary vessels is below the current resolution limit of optical coherence tomography angiography instruments, but areas of absent flow signal, called flow voids, are resolvable. The central macula was imaged with the Optovue RTVue XR Avanti using a 10-μm slab thickness in 104 eyes of 80 patients who ranged in age from 24 to 99 years of age. Automatic local thresholding of the resultant raw data with the Phansalkar method was analyzed with generalized estimating equations.
  
  
  RESULTS
  The distribution of flow voids vs size of the voids was highly skewed. The data showed a linear log-log plot and goodness-of-fit methods showed the data followed a power law distribution over the relevant range. A slope intercept relationship was also evaluated for the log transform and significant predictors for variables included age, hypertension, pseudodrusen, and the presence of late age-related macular degeneration (AMD) in the fellow eye.
  
  
  CONCLUSIONS
  The pattern of flow voids forms a scale invariant pattern in the choriocapillaris starting at a size much smaller than a choroidal lobule. Age and hypertension affect the choriocapillaris, a flat layer of capillaries that may serve as an observable surrogate for the neural or systemic microvasculature. Significant alterations detectable in the flow pattern in eyes with pseudodrusen and in eyes with late AMD in the fellow eye offer diagnostic possibilities and impact theories of disease pathogenesis.
authors: Vitreous, Retina, Macula Consultants of New York, New York, New York. Electronic address: rickspaide@gmail.com.
authors: Richard F
authors: RF
authors: Spaide
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity / Q000502:physiology; D002196:Capillaries / Q000502:physiology; D002829:Choroid / Q000098:blood supply*; D018450:Disease Progression; D005260:Female; D005451:Fluorescein Angiography; D006801:Humans; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000175:diagnosis / Q000503:physiopathology*; D012039:Regional Blood Flow; D015593:Retinal Drusen / Q000175:diagnosis / Q000503:physiopathology*; D012189:Retrospective Studies; D041623:Tomography, Optical Coherence; D014792:Visual Acuity; D057135:Wet Macular Degeneration / Q000175:diagnosis / Q000503:physiopathology*; D055815:Young Adult