Upper eyelid retraction after glaucoma filtering procedures.

After glaucoma filtration surgery, 2 patients developed overaction of Müller's muscle with resultant upper eyelid retraction. We theorize that stimulation of Müller's muscle is caused by a sympathomimetic chemical in the aqueous that travels from the bleb, under the bulbar and palpebral conjunctiva, to Muüller's muscle. In one case excision of Muüller's muscle relieved the retraction. In the other case, preventing aqueous from reaching Müller's muscle reduced the retraction.