title: A cohort study of duplex Doppler examinations of the carotid artery in primary open angle glaucoma.
abstract: OBJECTIVE
  To explore the possibility of pathological change in the common carotid artery at the bifurcation and in the internal carotid artery beyond the bifurcation which could contribute to a reduced diastolic pressure as observed in primary open angle glaucoma.
  
  
  METHODS
  Duplex ultrasonic examinations of carotid bifurcations were conducted on 80 patients. Carotid artery defects were allocated into three types: no demonstrable flow defects, internal carotid artery abnormalities and disease in the carotid bulb.
  
  
  METHODS
  Bristol Royal Infirmary Vascular Laboratory.
  
  
  METHODS
  Eighty patients (mean age 69.6 years) providing a total of 160 sides to the analysis.
  
  
  METHODS
  An estimated central retinal artery pressure, intraocular pressure and field loss were recorded for each side measured.
  
  
  RESULTS
  Doppler investigations revealed significant levels of pathological change in the internal carotid distinct from changes at the carotid bulb. The disease revealed in the internal carotid artery was significantly associated with intraocular pressure (p = 0.032), with an effect small to medium in magnitude. The Q2 measure, derived from mean arterial pressure and intraocular pressure, was also substantively associated with disease in the internal carotid artery. Both intraocular pressure and the Q2 measure effectively discriminated between groups, with field loss providing rather less discriminating capability. There was a strong trend towards a higher intraocular pressures and a greater visual field loss with internal carotid artery disease.
  
  
  CONCLUSIONS
  Pathological changes in the extra cranial carotid artery in primary open angle glaucoma exceed those in the arteries classified as normal. The presence of disease specifically in the internal carotid artery emphasised the need for a mechanism for the evaluation of the internal carotid apart from the carotid bulb. A basis for clarifying the presence of an ischaemic zone is proposed.
authors.affiliation: Bristol Eye Hospital, Bristol BS1 2LX, UK.
authors.forename: Vincent J
authors.initials: VJ
authors.lastname: Marmion
authors.affiliation: Huddersfield Royal Infirmary, Calderdale & Huddersfield NHS Foundation Trust, Huddersfield HD3 3EA, UK.
authors.forename: Munther I
authors.initials: MI
authors.lastname: Aldoori
authors.affiliation: School of Engineering, Cardiff University, Cardiff CF24 3AA, UK.
authors.forename: John P
authors.initials: JP
authors.lastname: Woodcock
authors.affiliation: School of Human and Health Sciences, University of Huddersfield, Queensgate, Huddersfield GB-HD1 3DH, UK.
authors.forename: John
authors.initials: J
authors.lastname: Stephenson
keywords: internal carotid artery; ischaemic index; primary open angle glaucoma; vascular resistance