title: A population-based assessment of 24-hour intraocular pressure among subjects with primary open-angle glaucoma: the handan eye study.
abstract: OBJECTIVE
  To describe the distribution of the 24-hour intraocular pressure (IOP) among subjects with primary open-angle glaucoma (POAG) in a population-based study in north China.
  
  
  METHODS
  All untreated POAG patients (n = 66) identified in the Handan Eye Study were invited to attend a follow-up study in which IOP was tested with a Goldmann applanation tonometer at 10 AM, 2 PM, 6 PM, 10 PM, 2 AM, and 6 AM.
  
  
  RESULTS
  Forty-seven subjects with untreated POAG (47/66; 71.2%) attended the study. Of them, 39 (83.0%) had a peak IOP ≤ 21 mm Hg. The peak IOP (mean ± SD) was 18.4 ± 3.7 mm Hg. Peak IOP occurred in early morning in approximately 76.5% of the subjects (6 AM to 10 AM), and the trough occurred during night time in 70.2% of the subjects (10 PM to 2 AM). The 24-hour IOP (mean ± SD) was 15.4 ± 3.1 mm Hg and the mean fluctuation was 6.0 ± 2.2 mm Hg (range, 2-11 mm Hg). In the 22 persons with unilateral glaucoma, no significant differences were found in mean 24-hour IOP, peak IOP, trough IOP, or IOP fluctuation when comparing the glaucomatous eye with the nonglaucomatous eye (P > 0.05).
  
  
  CONCLUSIONS
  About 80% of Chinese persons with POAG identified in a population-based study had maximum IOPs of 21 mm Hg or less over a 24-hour period. Twenty-four-hour IOP was similar between glaucomatous and contralateral nonglaucomatous eyes suggesting that factors other than IOP may play a role in the development of glaucomatous optic neuropathy in these eyes.
authors.affiliation: Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, China.
authors.forename: Ning Li
authors.initials: NL
authors.lastname: Wang
authors.forename: David S
authors.initials: DS
authors.lastname: Friedman
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhou
authors.forename: Lixia
authors.initials: L
authors.lastname: Guo
authors.forename: Dan
authors.initials: D
authors.lastname: Zhu
authors.forename: Yi
authors.initials: Y
authors.lastname: Peng
authors.forename: Dolly
authors.initials: D
authors.lastname: Chang
authors.forename: Lan Ping
authors.initials: LP
authors.lastname: Sun
authors.forename: Yuan Bo
authors.initials: YB
authors.lastname: Liang
mesh_terms: D000328:Adult; D000368:Aged; D044466:Asian People / Q000208:ethnology*; D002681:China / Q000453:epidemiology; D002940:Circadian Rhythm / Q000502:physiology*; D003315:Cornea / Q000000981:diagnostic imaging; D005260:Female; D005500:Follow-Up Studies; D005902:Glaucoma, Open-Angle / Q000208:ethnology* / Q000503:physiopathology*; D006068:Gonioscopy; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012424:Rural Population; D014065:Tonometry, Ocular; D014463:Ultrasonography; D014794:Visual Fields