title: Effect of nocturnal blood pressure reduction on circadian fluctuation of mean ocular perfusion pressure: a risk factor for normal tension glaucoma.
abstract: OBJECTIVE
  To study blood pressure (BP), intraocular pressure (IOP), and mean ocular perfusion pressure (MOPP) in patients with untreated normal tension glaucoma (NTG), and to investigate the relationship between circadian MOPP fluctuation and visual field status at initial presentation.
  
  
  METHODS
  IOP and BP were evaluated in hospital over 24 hours in 132 patients with NTG, with measurements taken every 2 hours between 12 PM and 10 AM the following day, except for the period between 12 and 6 AM, during which measurements were taken every 3 hours. MOPP was calculated from the 24-hour IOP and BP data. Patients were classified into three groups-nondippers, dippers, and overdippers-corresponding to the degree of reduction in their nocturnal mean arterial pressure (MAP) compared with their diurnal MAP. IOP and systemic and ocular hemodynamic parameters were compared among the groups. The correlations between circadian MOPP fluctuation and visual field scores (mean deviation [MD] and corrected pattern standard deviation [CPSD]) at initial presentation were analyzed.
  
  
  RESULTS
  Forty-one (31.1%) of the patients with NTGs were classified into the nondipper group, 36 (27.2%) into the dipper group, and 55 (41.7%) into the overdipper group. Marked circadian MOPP fluctuation was noted in the overdipper group (P < 0.05). Circadian MOPP fluctuation showed positive associations with visual field indices at initial diagnosis of NTG (P < 0.05, R2 = 0.056 with MD, R2 = 0.038 with CPSD).
  
  
  CONCLUSIONS
  Marked circadian MOPP fluctuation was associated with nocturnal BP reduction. Circadian MOPP fluctuation may be a risk factor for the development of NTG.
authors.affiliation: Department of Ophthalmology, University of Ulsan, College of Medicine, Asan Medical Center, Songpa-gu, Seoul, Republic of Korea.
authors.forename: Jaewan
authors.initials: J
authors.lastname: Choi
authors.forename: Jinho
authors.initials: J
authors.lastname: Jeong
authors.forename: Hyun-Soo
authors.initials: HS
authors.lastname: Cho
authors.forename: Michael S
authors.initials: MS
authors.lastname: Kook
mesh_terms: D001794:Blood Pressure / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D005123:Eye / Q000098:blood supply; D005260:Female; D005902:Glaucoma, Open-Angle / Q000503:physiopathology*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D014065:Tonometry, Ocular; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology