title: Anterior and posterior optic nerve head blood flow in nonhuman primate experimental glaucoma model measured by laser speckle imaging technique and microsphere method.
abstract: OBJECTIVE
  To characterize optic nerve head (ONH) blood flow (BF) changes in nonhuman primate experimental glaucoma (EG) using laser speckle flowgraphy (LSFG) and the microsphere method and to evaluate the correlation between the two methods.
  
  
  METHODS
  EG was induced in one eye each of 9 rhesus macaques by laser treatment to the trabecular meshwork. Prior to lasering and following onset of intraocular pressure (IOP) elevation, retinal never fiber layer thickness (RNFLT) and ONH BF were measured biweekly by spectral-domain optical coherence tomography and LSFG, respectively, until RNFLT loss was approximately 40% in the EG eye. Final BF was measured by LSFG and by the microsphere method in the anterior ONH (MS-BF(ANT)), posterior ONH (MS-BF(POST)), and peripapillary retina (MS-BF(PP)).
  
  
  RESULTS
  Baseline RNFLT and LSFG-BF showed no difference between the two eyes (P = 0.69 and P = 0.43, respectively, paired t-test). Mean (± SD) IOP was 30 ± 6 mm Hg in EG eyes and 13 ± 2 mm Hg in control eyes (P < 0.001). EG eye RNFLT and LSFG-BF were reduced by 42 ± 16% (P < 0.0001) and 22 ± 13% (P = 0.003), respectively, at the final time point. EG eye MS-BF(ANT), MS-BF(POST), and MS-BF(PP) were reduced by 41 ± 17% (P < 0.001), 22 ± 34% (P = 0.06), and 30 ± 12% (P = 0.001), respectively, compared with the control eyes. Interocular ONH LSFG-BF differences significantly correlated to that measured by the microsphere method (R(2) = 0.87, P < 0.001).
  
  
  CONCLUSIONS
  Chronic IOP elevation causes significant ONH BF decreases in the EG model. The high correlation between the BF reduction measured by LSFG and the microsphere method provides evidence that the LSFG is capable of assaying BF for a critical deep ONH region.
authors.affiliation: Devers Eye Institute, Legacy Research Institute, Portland, Oregon 97232, USA.
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.forename: Grant A
authors.initials: GA
authors.lastname: Cull
authors.forename: Chelsea
authors.initials: C
authors.lastname: Piper
authors.forename: Claude F
authors.initials: CF
authors.lastname: Burgoyne
authors.forename: Brad
authors.initials: B
authors.lastname: Fortune
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D019842:Ciliary Arteries / Q000502:physiology; D003941:Diagnostic Techniques, Ophthalmological; D004195:Disease Models, Animal; D005260:Female; D005901:Glaucoma / Q000503:physiopathology*; D007429:Intraocular Pressure; D007834:Lasers; D008253:Macaca mulatta; D008297:Male; D008863:Microspheres; D009412:Nerve Fibers / Q000473:pathology; D009898:Optic Disk / Q000098:blood supply*; D009901:Optic Nerve Diseases / Q000503:physiopathology*; D055420:Perfusion Imaging; D012039:Regional Blood Flow / Q000502:physiology; D012161:Retinal Artery / Q000502:physiology; D012165:Retinal Ganglion Cells / Q000473:pathology; D014065:Tonometry, Ocular