title: Optic nerve vasomotor effects of topical apraclonidine hydrochloride.
abstract: OBJECTIVE
  To examine, in vivo, the anterior optic nerve vasomotor effects of chronic apraclonidine hydrochloride in rabbits.
  
  
  METHODS
  After local treatment in one randomly chosen eye with apraclonidine hydrochloride 0.5% over 21 days, the microvasculature of the optic nerve was examined in five rabbits using an intraluminal microvascular corrosion casting technique. The investigators were masked as to which eye was treated. The vasoconstriction near the branching point of arterioles supplying the optic nerve was calculated as a percentage of the downstream vessel calibre. An average constriction was calculated and compared between the treated and the contralateral, untreated, eyes by means of a two tailed t test for paired variables. Constriction values of a total of 72 arterioles supplying the optic nerve were obtained for the five rabbits.
  
  
  RESULTS
  The average constriction in the treated and the control eyes was comparable (p = 0.96).
  
  
  CONCLUSIONS
  Chronic administration of apraclonidine hydrochloride 0.5% produces no observable optic nerve vasomotor effects in the rabbit eye.
authors.affiliation: Devers Eye Institute, Legacy Portland Hospitals, Oregon, USA.
authors.forename: S
authors.initials: S
authors.lastname: Orgül
authors.forename: D R
authors.initials: DR
authors.lastname: Bacon
authors.forename: E M
authors.initials: EM
authors.lastname: Van Buskirk
authors.forename: G A
authors.initials: GA
authors.lastname: Cioffi
mesh_terms: D000287:Administration, Topical; D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D003000:Clonidine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D005260:Female; D008297:Male; D008833:Microcirculation / Q000187:drug effects; D008855:Microscopy, Electron, Scanning; D009900:Optic Nerve / Q000098:blood supply* / Q000187:drug effects; D011817:Rabbits; D011897:Random Allocation; D014661:Vasoconstriction / Q000187:drug effects*
chemical_list: D000316:Adrenergic alpha-Agonists; C016986:apraclonidine; D003000:Clonidine