Prevalence and Predictors of Hering's Response in Müller's Muscle-conjunctival Resection

Unilateral MMCR induces a clinically relevant Hering's response in 8% of patients. A preoperative phenylephrine Hering's response does not predict a late postoperative Hering's response. Therefore, when unilateral phenylephrine testing unmasks contralateral blepharoptosis, only the side with blepharoptosis at baseline should be operated.