title: A Population-based Investigation of Circadian Rhythm of Intraocular Pressure in Habitual Position Among Healthy Subjects: The Handan Eye Study.
abstract: (1) To investigate the reference value of peak-trough difference in circadian rhythm of intraocular pressure (IOP) in habitual position and (2) to compare the IOP parameters among 3 age groups.
  
  
  
  Habitual IOP of healthy subjects sampled from the population in the Handan Eye Study was measured every 2 hours in the seated position during light-wake period (7:30 AM, 9:30 AM, 11:30 AM, 1:30 PM, 3:30 PM, 5:30 PM, 7:30 PM, 9:30 PM) and in the supine position during dark-sleep period (11:30 PM, 1:30 AM, 3:30 AM, 5:30 AM). Blood pressure and heart rate were obtained subsequently at each IOP measurement.
  
  
  
  Two hundred six healthy subjects were included in the final analyses (n=20, 30 to 39 y old; n=95, 40 to 49 y old; n=91, 50 to 59 y old). For peak-trough difference (7.2±2.3 mm Hg; 6.8 to 7.5 mm Hg, 95% confidence interval) in habitual position, the reference value was described as median 7.0 mm Hg, 25th percentile 5.5 mm Hg, and 95th percentile 11.5 mm Hg. No significant differences in peak-trough difference, acrophase (cosine-fit analysis derived peak timing) and amplitude (half distance between the cosine-fit maximum and minimum) were found among the 3 age groups. In the cosine model, the nocturnal acrophase (3:49±0.53 AM; 3:42 to 3:55 AM, 95% confidence interval) was detected for the entire group. Furthermore, 106 subjects (52%) had a nocturnal peak pattern, 36 subjects (17%) had a diurnal peak pattern, and 64 subjects (31%) had no evident pattern.
  
  
  
  In habitual position, 75% of healthy subjects from a population-based investigation had IOP variation >5.5 mm Hg and 95% subjects had <11.5 mm Hg variation. Aging may not influence the circadian habitual IOP rhythm.
authors.affiliation: *Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University †Beijing Ophthalmology & Visual Science Key Lab ‡Beijing Eye Institute §Capital Medical University, Beijing ¶Aier Ophthalmology Hospital, Nanjing #Hebei Eye Hospital, Hebei Key Laboratory of Ophthalmology, Xingtai **Handan Eye Hospital, Handan, China ∥Hamilton Glaucoma Center and Department of Ophthalmology, University of California, San Diego, La Jolla, CA.
authors.forename: Ning Li
authors.initials: NL
authors.lastname: Wang
authors.forename: Jie
authors.initials: J
authors.lastname: Hao
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhen
authors.forename: John H K
authors.initials: JH
authors.lastname: Liu
authors.forename: Si Zhen
authors.initials: SZ
authors.lastname: Li
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.forename: Xiao Xia
authors.initials: XX
authors.lastname: Peng
authors.forename: Wei
authors.initials: W
authors.lastname: Han
authors.forename: Su Jie
authors.initials: SJ
authors.lastname: Fan
authors.forename: Robert N
authors.initials: RN
authors.lastname: Weinreb
mesh_terms: D000328:Adult; D000375:Aging / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D064368:Healthy Volunteers; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011187:Posture / Q000502:physiology*; D012016:Reference Values; D012890:Sleep / Q000502:physiology; D014065:Tonometry, Ocular