title: Compromised Optic Nerve Blood Flow and Autoregulation Secondary to Neural Degeneration.
abstract: OBJECTIVE
  To test the hypothesis that optic nerve head (ONH) blood flow (BF) and autoregulation compromise are consequences of optic nerve degeneration induced by surgical optic nerve transection (ONT).
  
  
  METHODS
  In both eyes of five nonhuman primates, peripapillary retinal nerve fiber layer thickness (RNFLT) was measured by spectral-domain optical coherence tomography. Optic nerve head BF and dynamic autoregulation responses to a rapid manometric IOP increase (from 10-40 mm Hg) were measured by Laser Speckle Flowgraphy. The measurements were conducted every 10 to 15 days before and after unilateral ONT. Post-ONT measurements were repeated until RNFLT in the ONT eye was reduced by more than 40% of baseline value.
  
  
  RESULTS
  After ONT, RNFLT, and ONH BF progressively declined over time (P < 0.0001 and P = 0.02, respectively). Longitudinal changes between the two were highly correlated (P < 0.0001). When data was grouped by test session, the first significant decreases for RNFLT and BF were found 13 ± 0.8 and 24 ± 3.2 days post ONT, respectively (P < 0.05, both). At the final time point (55 ± 0.5 days post ONT), RNFLT, and BF were reduced by 44% ± 2.0% and 38 ± 5.0% from baseline, respectively. Dynamic autoregulation analysis showed marginal increased response time in post-ONT eyes (P = 0.05). Control eyes showed no longitudinal changes for any parameter.
  
  
  CONCLUSIONS
  The close association between RNFLT loss and ONH BF decrease following optic nerve degeneration demonstrated a clear cause and effect relationship. Increased BF response time appears to be a sign of dynamic autoregulation dysfunction in this ONT model.
authors.affiliation: Devers Eye Institute Legacy Research Institute, Portland, Oregon, United States.
authors.forename: Grant
authors.initials: G
authors.lastname: Cull
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Told
authors.affiliation: Devers Eye Institute Legacy Research Institute, Portland, Oregon, United States.
authors.forename: Claude F
authors.initials: CF
authors.lastname: Burgoyne
authors.affiliation: Devers Eye Institute Legacy Research Institute, Portland, Oregon, United States.
authors.forename: Simon
authors.initials: S
authors.lastname: Thompson
authors.affiliation: Devers Eye Institute Legacy Research Institute, Portland, Oregon, United States.
authors.forename: Brad
authors.initials: B
authors.lastname: Fortune
authors.affiliation: Devers Eye Institute Legacy Research Institute, Portland, Oregon, United States.
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology*; D004195:Disease Models, Animal; D006706:Homeostasis / Q000502:physiology*; D008253:Macaca mulatta; D008297:Male; D009896:Optic Atrophy / Q000473:pathology / Q000503:physiopathology*; D009900:Optic Nerve / Q000098:blood supply*; D012039:Regional Blood Flow / Q000502:physiology*; D041623:Tomography, Optical Coherence / Q000379:methods