Intraocular pressure elevation after pupillary dilation in open angle glaucoma.

Acute elevation of intraocular pressure frequently follows pupillary dilation in patients with primary open angle glaucoma. A retrospective study of 60 patients (116 eyes) with primary open angle glaucoma was done to assess the frequency and severity of intraocular pressure elevation following dilation with 2.5% phenylephrine hydrochloride (Neo-Synephrine) and 1% tropicamide (Mydriacyl). Significant pressure elevation (greater than 5 mm Hg) occurred in 37 eyes (32%). Marked pressure elevation (greater than 10 mm Hg) occurred in 14 eyes (12%). The only significant risk factor found was treatment with miotics. The change of intraocular pressure one hour after dilation was compared with the one-hour postoperative change in intraocular pressure in those patients (12 patients, 18 eyes) who subsequently underwent argon laser trabeculoplasty. No statistically significant correlation was found. There is a potential hazard of routine dilation of eyes with open angle glaucoma.