title: Optic nerve head circulation after topical calcium channel blocker.
abstract: OBJECTIVE
  Our purpose was to investigate the effects of the calcium channel blocker verapamil on intraocular pressure and blood circulation in the human optic nerve head.
  
  
  METHODS
  The effects of three different concentrations of topical verapamil (0.063%, 0.125%, and 0.25%) on intraocular pressure and optic nerve head capillary blood speed were measured in 12 healthy normal subjects. In a randomized, double-masked design, each subject received one drop of either verapamil or placebo in one eye and the opposite treatment in the fellow eye. Anterior optic nerve circulation was assessed at baseline and 90 min after instillation of the drops using the laser Doppler technique.
  
  
  RESULTS
  The intraocular pressure was significantly reduced compared with baseline in both verapamil- and placebo-treated eyes at each concentration. The reductions of intraocular pressure were greater in verapamil-treated eyes (12-17%) than in placebo-treated eyes (9-12%). No systemic effect on heart rate or blood pressure was detected after administration of topical verapamil. The capillary blood speed in the optic nerve head was increased in both verapamil- and placebo-treated eyes at each concentration, although the only statistically significant increases were with the 0.25% concentration. The mean +/- SEM increase compared with baseline at the 0.25% concentration was 10.4 +/- 3.6% in verapamil-treated eyes (p = 0.017), and 11.6 +/- 4.4% in placebo-treated eyes (p = 0.026).
  
  
  CONCLUSIONS
  These results indicate that topical administration of verapamil lowers the intraocular pressure and increases the capillary blood speed in the optic nerve head in normal subjects. Changes measured in verapamil-treated eyes were also observed in placebo-treated eyes, indicating a crossover effect.
authors.affiliation: Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Boston 02114, USA.
authors.forename: P A
authors.initials: PA
authors.lastname: Netland
authors.forename: G T
authors.initials: GT
authors.lastname: Feke
authors.forename: S
authors.initials: S
authors.lastname: Konno
authors.forename: D G
authors.initials: DG
authors.lastname: Goger
authors.forename: N
authors.initials: N
authors.lastname: Fujio
mesh_terms: D000287:Administration, Topical; D000328:Adult; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000187:drug effects; D017078:Laser-Doppler Flowmetry; D008297:Male; D008875:Middle Aged; D009898:Optic Disk / Q000098:blood supply / Q000187:drug effects*; D009994:Osmolar Concentration; D012016:Reference Values; D012039:Regional Blood Flow / Q000187:drug effects; D014700:Verapamil / Q000494:pharmacology*
chemical_list: D002121:Calcium Channel Blockers; D014700:Verapamil