title: Retinal blood flow during dynamic exercise.
abstract: BACKGROUND
  Exercise acutely lowers intraocular pressure (IOP) and raises arterial pressure. We wondered whether the resultant increase in ocular perfusion pressure would alter retinal blood flow.
  
  
  METHODS
  To investigate this question, 11 healthy volunteers each performed progressive cycle ergometer exercise until exhaustion was reached in 5-10 min. Immediately after exercise, retinal blood flow and arteriovenous passage time were determined by video fluorescein angiography. Ten other volunteers performed repeated episodes of cycle ergometer exercise at approximately 60% of the maximal aerobic capacity, immediately prior to estimates of macular leukocyte velocity and density via blue-field stimulation.
  
  
  RESULTS
  Progressive exercise lowered IOP and elevated calculated ocular perfusion pressure. Within the retinal circulation, this exercise tended to raise mean dye velocity, as it significantly narrowed the superior temporal artery and vein; as a result, calculated retinal blood flow was unchanged. Simultaneously, retinal arteriovenous passage time was substantially shortened. Blue-field simulation showed that exercise increased macular leukocyte velocity while leaving leukocyte density unchanged.
  
  
  CONCLUSIONS
  These results show that the normal retinal hemodynamic response to increases in perfusion pressure on dynamic exercise includes vasoconstriction that normalizes flow and faster capillary and overall retinal blood transit.
authors.affiliation: Department of Physiology and Biophysics, Indiana University School of Medicine, Indianapolis 46202-5175, USA.
authors.forename: A
authors.initials: A
authors.lastname: Harris
authors.forename: O
authors.initials: O
authors.lastname: Arend
authors.forename: K
authors.initials: K
authors.lastname: Bohnke
authors.forename: E
authors.initials: E
authors.lastname: Kroepfl
authors.forename: R
authors.initials: R
authors.lastname: Danis
authors.forename: B
authors.initials: B
authors.lastname: Martin
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D001794:Blood Pressure; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D005451:Fluorescein Angiography; D005654:Fundus Oculi; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D012039:Regional Blood Flow; D012171:Retinal Vessels / Q000502:physiology*