title: The effect of lateral decubitus position on nocturnal intraocular pressure over a habitual 24-hour period in healthy adults.
abstract: OBJECTIVE
  To investigate the effect of lateral decubitus position (LDP) on nocturnal intraocular pressure (IOP) and the effect of LDP on 24-hour habitual IOP pattern in healthy subjects.
  
  
  METHODS
  Intraocular pressure was measured every 2-hours using an Accupen Applanation Tonometer (Accutome, USA). During the diurnal period (7:30 am, 9:30 am, 11:30 am, 1:30 pm, 3:30 pm, 5:30 pm, 7:30 pm, and 9:30 pm), IOP was measured in the sitting position under bright light (500-1000 lux) after the subjects had been seated for 5 min. The nocturnal IOP was measured in the supine position, right LDP, and left LDP, with randomized sequences, under dim light (<10 lux) at 11:30 pm, 1:30 am, 3:30 am, and 5:30 am. The subjects were awakened and maintained each position for 5 min before the measurement. The 24-hour habitual IOP patterns were obtained according to the nocturnal position (supine, right LDP and left LDP) for either eye. P<0.05 was considered to be significant.
  
  
  RESULTS
  Nineteen healthy subjects were included with a mean age of 51.3±5.8 years. During the nocturnal period, a significant IOP difference was found between the dependent eye (the eye on the lower side) of LDP and the supine position, but not for all the nocturnal time points. Over a 24-hour period, the effect of LDP on habitual IOP pattern was not statistically significant, although the mean nocturnal IOP and the diurnal-nocturnal IOP change for the right and the left eye in the LDP pattern was slightly higher than that in the sitting-supine pattern.
  
  
  CONCLUSIONS
  Significant nocturnal IOP differences existed between the dependent eye and the supine, but did not occur consistently for all time points. Over a 24-hour period, the effect of LDP on habitual IOP pattern was not statistically significant in healthy subjects.
authors.affiliation: Beijing Tongren Eye Center, Beijing Ophthalmology & Visual Sciences Key Laboratory,Beijing Tongren Hospital, Capital Medical University, Beijing, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Hao
authors.affiliation: Beijing Tongren Eye Center, Beijing Ophthalmology & Visual Sciences Key Laboratory,Beijing Tongren Hospital, Capital Medical University, Beijing, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhen
authors.affiliation: Hebei Eye Hospital, Hebei Key Laboratory of Ophthalmology, Xingtai, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.affiliation: Beijing Tongren Eye Center, Beijing Ophthalmology & Visual Sciences Key Laboratory,Beijing Tongren Hospital, Capital Medical University, Beijing, China.
authors.forename: Diya
authors.initials: D
authors.lastname: Yang
authors.affiliation: Beijing Tongren Eye Center, Beijing Ophthalmology & Visual Sciences Key Laboratory,Beijing Tongren Hospital, Capital Medical University, Beijing, China.
authors.forename: Ningli
authors.initials: N
authors.lastname: Wang
mesh_terms: D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D056888:Patient Positioning; D014065:Tonometry, Ocular