title: Changes in intraocular pressure after pharmacologic pupil dilation.
abstract: BACKGROUND
  Intraocular pressure (IOP) may vary according to the change of ocular conditions. In this study, we want to assess the effect and mechanism of pupil dilation on IOP in normal subjects.
  
  
  METHODS
  We prospectively evaluated 32 eyes of 32 patients (age; 61.7±8.2 years) with normal open angles under diurnal IOP. IOP was measured every two hours from 9 AM to 11 PM for one day to establish baseline values and was measured again for one day to assess the differences after dilation. To induce dilation, we administered 2.5% phenylephrine and 1% tropicamide every 5 minutes from 8:30 AM to 8:45 AM and for every two hours from 11 AM to 9 PM to keep the pupil dilated. Diurnal IOP, biometry, Visante OCT, and laser flare photometry were measured before and after dilation.
  
  
  RESULTS
  We observed a significant increase in IOP after dilation, 1.85±2.01 mmHg (p=0.002). IOP elevation remained significant until about four hours after dilation. Thereafter, IOP decreased slowly and eventually reached pre-dilation level (p>0.05). Flare values decreased, and the anterior chamber angle became wider after mydriasis.
  
  
  CONCLUSIONS
  Dilation of the pupil significantly and incidentally elevated IOP in normal subjects. Further related studies are warranted to characterize the mechanism of the increased IOP after dilation.
authors.affiliation: Department of Ophthalmology, Sungkyunkwan University School of Medicine, Kangbuk Samsung Hospital, Seoul, Korea.
authors.forename: Joon Mo
authors.initials: JM
authors.lastname: Kim
authors.forename: Ki Ho
authors.initials: KH
authors.lastname: Park
authors.forename: So Young
authors.initials: SY
authors.lastname: Han
authors.forename: Kwan Soo
authors.initials: KS
authors.lastname: Kim
authors.forename: Dong Myung
authors.initials: DM
authors.lastname: Kim
authors.forename: Tae Woo
authors.initials: TW
authors.lastname: Kim
authors.forename: Joseph
authors.initials: J
authors.lastname: Caprioli
mesh_terms: D005260:Female; D005500:Follow-Up Studies; D005902:Glaucoma, Open-Angle / Q000188:drug therapy / Q000503:physiopathology*; D006801:Humans; D007429:Intraocular Pressure / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009184:Mydriatics / Q000008:administration & dosage*; D009883:Ophthalmic Solutions; D011446:Prospective Studies; D011680:Pupil / Q000187:drug effects*; D014065:Tonometry, Ocular
chemical_list: D009184:Mydriatics; D009883:Ophthalmic Solutions