The Effect of Hering's Law on Different Ptosis Repair Methods.

Abstract

The Hering's law effect has significant importance in surgical planning and outcomes of eyelid surgery. The current study examined the preoperative and intraoperative effect of Hering's law in Mullerectomy and levator aponeurosis advancement. A retrospective analysis was conducted of 52 patients with unilateral ptosis who underwent surgical repair from January 2011 through June 2013. Patients underwent levator aponeurosis advancement or Mullerectomy with or without tarsectomy. Preoperative and postoperative clinical documentation and photographs were evaluated. Preoperative Hering's dependency and postoperative changes in positioning of the non-operated eyelid were measured. The decision to operate on the ptotic eye alone or on both eyelids was based on preoperative Hering's dependence and intraoperative changes in the contralateral eyelid. Fifty-two patients with unilateral ptosis were included. Average age was 63.3 ± 20.1 years (range, 22-88 years; median, 61 years); 34 (65.4%) were female. The 14 cases that were not aponeurotic (either congenital, secondary to trauma, or due to postoperative ptosis) did not need contralateral repair (p = .000). In 4 (19%) cases of Mullerectomy and in 9 (52.9%) cases of levator advancement, both eyelids required surgery (p = .029). Hering's law effect was significantly more apparent in the levator advancement approach than in Mullerectomy. Levator surgery resulted in a higher incidence of combined intraoperative and postoperative Hering's law effect than did Mullerectomy. Cases with poor levator function or congenital ptosis can be repaired unilaterally with no need for contralateral surgery. The fibrotic levator palpebrae muscle and its special innervations probably explain this phenomenon. This should be considered in surgical planning.