title: Longitudinal hemodynamic changes within the optic nerve head in experimental glaucoma.
abstract: OBJECTIVE
  To characterize longitudinal changes in basal blood flow (BF) of the optic nerve head (ONH) during progression of structural damage in experimental glaucoma (EG).
  
  
  METHODS
  Unilateral elevation of IOP was induced in 15 adult rhesus macaques by laser treatment to the trabecular meshwork. Prior to and after laser, retinal nerve fiber layer thickness (RNFLT) and ONH BF were measured biweekly by spectral-domain optical coherence tomography and a laser speckle flowgraphy device (LSFG), respectively.
  
  
  RESULTS
  Average postlaser IOP was 20.2 ± 5.9 mm Hg in EG eyes and 12.3 ± 2.6 mm Hg in control eyes (P < 0.0001). Longitudinal changes in basal ONH BF were strongly associated with changes in RNFLT as EG progressed from early through moderately advanced stages of damage, with Pearson correlation coefficients ranging from 0.64 to 0.97 (average = 0.81) and an average slope of 1.0. During early stage (RNFLT loss < 10%), basal ONH BF was mildly increased (9% ± 10%, P = 0.004) relative to baseline and compared with fellow controls (P = 0.02). Basal ONH BF declined continuously throughout subsequent stages in EG eyes reaching 25.0% ± 9.6% (P < 0.0001) below baseline at the final stage studied (RNFLT loss > 40%). In fellow control eyes, there was no significant change in basal ONH BF over time (P = 0.27).
  
  
  CONCLUSIONS
  In EG based on chronic mild-to-moderate IOP elevation, a two-phase pattern of ONH BF alteration was observed. ONH BF increased during the earliest stage (while RNFLT was within 10% of baseline) followed by a linear decline that was strongly correlated with loss of RNFLT.
authors.affiliation: Devers Eye Institute, Legacy Research Institute, Portland, Oregon, USA.
authors.forename: Grant
authors.initials: G
authors.lastname: Cull
authors.forename: Claude F
authors.initials: CF
authors.lastname: Burgoyne
authors.forename: Brad
authors.initials: B
authors.lastname: Fortune
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D004195:Disease Models, Animal; D005260:Female; D005901:Glaucoma / Q000503:physiopathology*; D007429:Intraocular Pressure / Q000502:physiology; D017078:Laser-Doppler Flowmetry; D008137:Longitudinal Studies; D008253:Macaca mulatta; D008297:Male; D009412:Nerve Fibers / Q000473:pathology; D009898:Optic Disk / Q000098:blood supply*; D009901:Optic Nerve Diseases / Q000503:physiopathology*; D012039:Regional Blood Flow / Q000502:physiology; D012165:Retinal Ganglion Cells / Q000473:pathology; D041623:Tomography, Optical Coherence; D014065:Tonometry, Ocular
keywords: blood flow; experimental glaucoma; intraocular pressure; optic nerve head