title: Ocular perfusion pressure and ophthalmic artery flow in patients with normal tension glaucoma.
abstract: BACKGROUND
  Vascular insufficiency has been reported to be a cause of normal tension glaucoma (NTG). The aim of this study was to compare ocular perfusion pressure (OPP) and ophthalmic artery flow (OAF) between patients with NTG and those without glaucoma.
  
  
  METHODS
  We considered one eye each from 31 NTG and 15 non-glaucoma control patients. Blood pressure and intraocular pressure (IOP) were measured in the sitting position, for calculation of OPP. Humphrey visual field (HVF) assessment was then carried out on NTG patients. All patients then underwent Transcranial Doppler ultrasound measurements of OAF parameters, including mean flow velocity (MFV), end diastolic velocity (EDV), peak systolic velocity (PSV) and resistive index (RI). We looked at differences in OPP and OAF parameters between the two groups, and their correlations in NTG patients. T-tests, χ (2), ANOVA and Pearson Correlation tests were performed, with p < 0.05 considered statistically significant.
  
  
  RESULTS
  There were no statistically significant differences in OPP between the NTG and control groups (60.5+/-8.7 mmHg and 62.9+/-10.2 mmHg respectively, p = 0.393), and also no statistically significant differences in MFV, EDV, PSV and RI (all p > 0.05). In the NTG group, there were positive correlations between OPP and both MFV (r = 0.416, p = 0.020) and EDV (r = 0.369, p = 0.041). There were no statistically significant correlations between HVF mean deviation and OPP or OAF parameters (all p > 0.05).
  
  
  CONCLUSIONS
  There is no difference in OPP and OAF parameters between patients with NTG and non-glaucoma controls, suggesting that vascular insufficiency or dysregulation by themselves may not account for the pathogenesis of NTG.
authors.affiliation: Department of Ophthalmology, University of Malaya Eye Research Centre, University of Malaya, Kuala Lumpur, Malaysia. amir@ummc.edu.my.
authors.forename: Amir
authors.initials: A
authors.lastname: Samsudin
authors.affiliation: Department of Ophthalmology, University of Malaya Eye Research Centre, University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: Nadine
authors.initials: N
authors.lastname: Isaacs
authors.affiliation: Division of Neurology, Department of Medicine, University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: Mei-Ling Sharon
authors.initials: ML
authors.lastname: Tai
authors.affiliation: Department of Ophthalmology, University of Malaya Eye Research Centre, University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: Norlina
authors.initials: N
authors.lastname: Ramli
authors.affiliation: Department of Ophthalmology, University of Malaya Eye Research Centre, University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: Zahari
authors.initials: Z
authors.lastname: Mimiwati
authors.affiliation: Department of Ophthalmology, University of Malaya Eye Research Centre, University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: May May
authors.initials: MM
authors.lastname: Choo
mesh_terms: D000368:Aged; D062186:Arterial Pressure / Q000502:physiology*; D001783:Blood Flow Velocity; D001794:Blood Pressure / Q000502:physiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D057066:Low Tension Glaucoma / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009880:Ophthalmic Artery / Q000502:physiology*; D017585:Ultrasonography, Doppler, Transcranial