Purpose:
To assess the effects of dilation on diurnal intraocular pressure(IOP).
Methods:
We prospectively evaluated 32 eyes of 32 patients (17 womenand 15 men, mean age 61.7 ± 8.2 years) with normal openangles for fluctuations in diurnal IOP. Diurnal IOP was measuredevery two hours from 9 AM to 11 PM for one day to establishbaseline values and for one day to assess values after dilation.To induce dilation, we administered 2.5% phenylephrine and 1%tropicamide every 10 minutes from 8:30 AM to 9:00 AM, and everytwo hours from 9 AM to 9 PM. Diurnal IOP, biometry, VisanteOCT, and laser flare photometry were measured before and afterdilation.
Results:
We observed a significant increase in IOP after dilation of1.85 ± 2.01 mmHg (p=0.002). IOP elevation remained significantuntil about four hours after dilation. Thereafter, IOP decreasedslowly, eventually reached predilation levels (p>0.05). Flarevalues decreased and anterior chamber angles became wider aftermydriasis.
Conclusions:
IOP was found to be significantly increased until 4 to 6 hoursafter dilation, and slowly decreased after that time, althoughdilation was maintained. After dilation, anterior chamber depthwas deepened, anterior chamber angle was widened, and anteriorchamber flare was decreased. Dilation of pupil significantlyelevated IOP which may be due to temporary decrease in the outflowfacility caused by crowding of flare into the trabecular meshwork.
Clinical Trial:
www.anzctr.org.au 00320840
Keywords: intraocular pressure • anterior chamber