title: [Ocular blood flow regulation in glaucoma - examination with the ocular pressure flow analyzer (OPFA)].
abstract: BACKGROUND
  The results of studies of ocular blood flow (BF) regulation of patients with primary open-angle glaucoma (POAG), normal-tension glaucoma (NTG) and ocular hypertension (OH) are presented.
  
  
  METHODS
  Examinations were carried out with the "OPFA", a newly developed ocular pressure flow analyzer (producer: tpm Lüneburg) on 92 patients with newly diagnosed glaucomas, among whom 48 patients had POAG, 22 NTG and 22 OH, and compared with age-matched groups of healthy subjects. The OPFA uses pneumatic coupling through special scleral suction cups to record ocular pulses with highly sensitive transducers and a suction pump for simultaneously increasing intraocular pressure (IOP). Following local drop anaesthesia on both eyes, IOP is artificially raised to suprasystolic values. While continuously lowering IOP, the ocular pulse is then recorded with increasing ocular perfusion pressure. We obtain the relative ocular pulse blood volume by correlating the ocular pulse amplitudes with a calibration volume of 1 µl. This enables us to collect reproducible data on intra- and inter-individual pulse blood volume (PVoc). The ocular perfusion pressure pulse blood volume curve characterizes the respective individual ocular circulation as well as systolic and diastolic ocular perfusion pressures.
  
  
  RESULTS
  In healthy subjects, the ocular pulse blood volume remains stable over a certain range of ocular perfusion pressure (ppoc) changes. After exceeding a critical point (CP), the ocular pulse blood volume drops. We refer to the difference between the CP and IOP as the autoregulatory capacity (AC). In patients with POAG and in patients with NTG, the AC was reduced significantly compared with the groups of healthy subjects. The mean AC of patients with OH remained within the normal range. The ROC curves showed at an optimal cut-off value for POAG a sensitivity of 75.0 % and a specificity of 97.9 %, for NTG a sensitivity of 77.3 % and a specificity of 100 %. In patients with POAG and OH, the ocular arterial pressures were elevated. In patients with NTG they remained unchanged compared with the healthy subjects. The ocular perfusion pressures did not change in POAG as well as in NTG and OH.
  
  
  CONCLUSIONS
  In patients with POAG and in patients with NTG the ocular BF regulation was impaired and detected by the OPFA device with a high level of reliability. Ocular arterial blood pressures were increased as a result of vascular regulation to keep up the ocular perfusion pressure and to maintain ocular perfusion.
authors.affiliation: Augenarztpraxis, 04552 Borna.
authors.forename: W-D
authors.initials: WD
authors.lastname: Ulrich
authors.affiliation: Augenarztpraxis, 04552 Borna.
authors.forename: A
authors.initials: A
authors.lastname: Moeller
authors.affiliation: Augenarztpraxis, 04552 Borna.
authors.forename: C
authors.initials: C
authors.lastname: Ulrich
authors.affiliation: Sostana GmbH, 10117 Berlin.
authors.forename: G
authors.initials: G
authors.lastname: Siebert
authors.affiliation: Sostana GmbH, 10117 Berlin.
authors.forename: K-D
authors.initials: KD
authors.lastname: Wernecke
authors.affiliation: Augenklinik am Wittenbergplatz, 10787 Berlin.
authors.forename: C
authors.initials: C
authors.lastname: Erb
mesh_terms: D001783:Blood Flow Velocity; D001795:Blood Pressure Determination / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D005901:Glaucoma / Q000175:diagnosis* / Q000503:physiopathology*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014065:Tonometry, Ocular / Q000295:instrumentation*