title: A comparative study of betaxolol and dorzolamide effect on ocular circulation in normal-tension glaucoma patients.
abstract: OBJECTIVE
  To determine whether dosages of a selective beta-blocking agent (betaxolol) and a topical carbonic anhydrase inhibitor (dorzolamide), sufficient to significantly lower intraocular pressure (IOP), have similar or disparate impact on the retinal and retrobulbar circulation.
  
  
  METHODS
  Counterbalanced crossover, with open-label use of medications.
  
  
  METHODS
  Nine persons with normal-tension glaucoma (NTG).
  
  
  METHODS
  After a 3-week drug washout, NTG patients were studied after 1 month of treatment with either dorzolamide or betaxolol, with determinations of IOP and retinal and retrobulbar hemodynamics.
  
  
  METHODS
  At baseline and after treatment with each drug, retinal arteriovenous passage time was determined by scanning laser ophthalmoscopy after fluorescein dye injection, and flow velocities in the central retinal and ophthalmic arteries were measured with color Doppler ultrasonography imaging.
  
  
  RESULTS
  Betaxolol and dorzolamide each lowered IOP significantly, with these changes apparent and maximal after 2 weeks (each P < 0.05). In contrast, dorzolamide (but not betaxolol) accelerated arteriovenous passage of fluorescein dye in the inferior temporal quadrant of the retina (P < 0.05). Neither drug affected arteriovenous passage in the superotemporal retina or any aspect of central retinal or ophthalmic artery flow velocity after either 2 or 4 weeks.
  
  
  CONCLUSIONS
  Although both dorzolamide and betaxolol are effective ocular hypotensive agents and their topical instillation leaves retrobulbar hemodynamics unaltered, dorzolamide alone accelerates inferotemporal retinal dye transit.
authors.affiliation: Department of Ophthalmology, 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: H S
authors.initials: HS
authors.lastname: Chung
authors.forename: L
authors.initials: L
authors.lastname: Kagemann
authors.forename: L
authors.initials: L
authors.lastname: Cantor
authors.forename: B
authors.initials: B
authors.lastname: Martin
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000627:therapeutic use*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015784:Betaxolol / Q000008:administration & dosage / Q000627:therapeutic use*; D001783:Blood Flow Velocity / Q000187:drug effects; D002257:Carbonic Anhydrase Inhibitors / Q000008:administration & dosage / Q000627:therapeutic use*; D018592:Cross-Over Studies; D005260:Female; D019793:Fluorescein / Q000378:metabolism; D005902:Glaucoma, Open-Angle / Q000188:drug therapy* / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009880:Ophthalmic Artery / Q000000981:diagnostic imaging / Q000503:physiopathology*; D009883:Ophthalmic Solutions / Q000008:administration & dosage / Q000627:therapeutic use; D012161:Retinal Artery / Q000000981:diagnostic imaging / Q000503:physiopathology*; D013449:Sulfonamides / Q000008:administration & dosage / Q000627:therapeutic use*; D013876:Thiophenes / Q000008:administration & dosage / Q000627:therapeutic use*; D018615:Ultrasonography, Doppler, Color
chemical_list: D000319:Adrenergic beta-Antagonists; D002257:Carbonic Anhydrase Inhibitors; D009883:Ophthalmic Solutions; D013449:Sulfonamides; D013876:Thiophenes; C062765:dorzolamide; D015784:Betaxolol; D019793:Fluorescein