Palpebral fissure responses to topical adrenergic drugs

We measured the magnitude and time course of the increase in palpebral fissure width in ten normal volunteers in response to direct-acting (2.5% phenylephrine, 1% apraclonidine) and indirect-acting (10% cocaine, 1% hydroxyamphetamine) topical adrenergic drugs given in one eye. The increase in the palpebral fissure width of the treated eye was compared to the width of the untreated, control eye during a period of 60 minutes after each drug was administered. The difference in fissure width (asymmetry) between the treated and untreated eyes increased significantly for all drugs during the three- to 60-minute time period after treatment. There was no significant difference in the maximum eyelid effect among the adrenergic drugs tested. The drugs exerted their maximum effect by 30 minutes in 39 of the 40 trials (97.5%). The direct-acting drugs tended to exert their effect more quickly than the indirect-acting drugs. Our results demonstrate the expected increase in palpebral fissure width in response to topical adrenergic drugs in normal eyes. This information will provide a basis for evaluating Müller's muscle and its sympathetic innervation in patients with blepharoptosis.