title: Dorzolamide influences the autoregulation of major retinal vessels caused by artificial intraocular pressure elevation in patients with POAG: a clinical study.
abstract: OBJECTIVE
  The study investigated whether dorzolamide influences the autoregulatory behavior of major retinal arterioles in glaucoma patients via a moderate perfusion pressure reduction.
  
  
  METHODS
  The study included one eye each of 12 untreated patients with a primary open-angle glaucoma (POAG) (age 60.8 +/- 8.3, IOP 22.3 +/- 6.5 mmHg). Changes in the diameter of a retinal artery segment before (120 s), during (100 s), and after (380 s) artificial IOP elevation to 38 mmHg for 100 s were recorded continuously by means of a Retinal Vessel Analyzer. The measurement was repeated after 4-week treatment with dorzolamide eye drops t.i.d.
  
  
  RESULTS
  Ocular perfusion pressure (mmHg) was reduced by the intraocular pressure (IOP) elevation from 58 (+/- 10) to 41 (+/- 11) in the pretreatment examination and from 60 (+/- 8) to 40 (+/- 8) posttreatment (differences between the examinations n.s.). Before IOP elevation, the arterial diameter was found to be +1.7 +/- 3.5% greater in the posttreated eyes than in the pretreated eyes (p < 0.02). During IOP elevation, the arterial diameter decreased by -1.8% +/- 3.8 in the pretreated eyes, whereas dilatation by +1.4% +/- 2.5 was observed in the posttreated eyes (p = 0.02). At the end of the observation period following IOP elevation, the vessel diameter in the pretreated eyes had increased by +1.8% +/- 4.2, whereas in the posttreated eyes it had decreased by -1.7% +/- 3.0. On average, dorzolamide reduced IOP by -5.6 mmHg (p = 0.001).
  
  
  CONCLUSIONS
  The arterial diameter dilatation during IOP elevation in dorzolamide-treated eyes could be an accelerated counter-regulation on the induced elevated IOP and could constitute an additional therapeutic effect.
authors.affiliation: Rudolstadt Ophthalmologic Practice, Rudolstadt, Germany. e_a_nagel@t-online.de
authors.forename: Edgar
authors.initials: E
authors.lastname: Nagel
authors.forename: Walthard
authors.initials: W
authors.lastname: Vilser
authors.forename: Ines
authors.initials: I
authors.lastname: Lanzl
mesh_terms: D000368:Aged; D001794:Blood Pressure; D002257:Carbonic Anhydrase Inhibitors / Q000627:therapeutic use*; D005260:Female; D005902:Glaucoma, Open-Angle / Q000188:drug therapy* / Q000503:physiopathology*; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000503:physiopathology; D009798:Ocular Hypertension / Q000503:physiopathology; D009883:Ophthalmic Solutions; D012161:Retinal Artery / Q000503:physiopathology*; D013449:Sulfonamides / Q000627:therapeutic use*; D013876:Thiophenes / Q000627:therapeutic use*; D014664:Vasodilation
chemical_list: D002257:Carbonic Anhydrase Inhibitors; D009883:Ophthalmic Solutions; D013449:Sulfonamides; D013876:Thiophenes; C062765:dorzolamide