title: Color Doppler ultrasound analysis of ocular circulation after topical calcium channel blocker.
abstract: OBJECTIVE
  To investigate the effect of topical administration of the calcium channel blocker verapamil on intraocular pressure and retrobulbar hemodynamics.
  
  
  METHODS
  In this randomized, prospective, double-masked study, we examined the effects of single-dose topical administration of verapamil in ten normal human volunteers by using color Doppler ultrasound imaging to measure hemodynamic parameters. Limitations of this study include single-dose application of verapamil and relatively small sample size.
  
  
  RESULTS
  No systemic effect on heart rate or blood pressure was detected after administration of topical verapamil. The intraocular pressure significantly decreased compared with baseline two hours after topical 0.125% and 0.25% verapamil (P = .015 and .040, respectively). Pourcelot's ratio, an index of vascular resistance, measured in the central retinal artery was significantly reduced after topical application of 0.125% verapamil (P = .008). The change in Pourcelot's ratio primarily resulted from an increased end diastolic velocity in the central retinal artery. No significant differences compared with baseline values were detected in the color Doppler ultrasound measurements of the posterior ciliary arteries and the central retinal vein two hours after topically administered verapamil.
  
  
  CONCLUSIONS
  Topical administration of verapamil decreases intraocular pressure and alters ocular hemodynamics, reducing the vascular resistance index in the central retinal artery.
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: C L
authors.initials: CL
authors.lastname: Grosskreutz
authors.forename: G T
authors.initials: GT
authors.lastname: Feke
authors.forename: L J
authors.initials: LJ
authors.lastname: Hart
mesh_terms: D000287:Administration, Topical; D000328:Adult; D001158:Arteries / Q000000981:diagnostic imaging; D001775:Blood Circulation / Q000187:drug effects; D002924:Ciliary Body / Q000098:blood supply / Q000000981:diagnostic imaging; D004311:Double-Blind Method; D005123:Eye / Q000098:blood supply* / Q000000981:diagnostic imaging / Q000187:drug effects*; D005260:Female; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007429:Intraocular Pressure / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009883:Ophthalmic Solutions; D011446:Prospective Studies; D012171:Retinal Vessels / Q000000981:diagnostic imaging / Q000502:physiology; D018615:Ultrasonography, Doppler, Color; D014700:Verapamil / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D009883:Ophthalmic Solutions; D014700:Verapamil