Abstract
Purpose :
External levator resection(ELR) and Müller’s muscle conjunctival resection(MMCR) differ in the tissues dissected during surgery. This study aims to determine if resection of purely the levator aponeurosis or Müller’s muscle and conjunctiva has a differential effect on variation in eyelid position after surgery.
Methods :
In this retrospective observational cohort study, patients from two practices undergoing surgery for involutional ptosis over a 10-year period were screened. Exclusion criteria includes trauma, ocular disease, or past orbital surgery. Patients underwent MMCR surgery (RAG) or ELR (NJ). Marginal reflex distance (MRD) was calculated on photos using NIH ImageJ software. Measurements were made at baseline, 1 week postoperatively and at 3 to 12 months follow up. The primary outcome measure was change in MRD over time. The secondary outcome measure was the proportion of patients with minimal early change in MRD (< 0.5 mm at 1 week). Repeated measures ANOVA, T-test and Chi square tests were performed.
Results :
Of 135 eyes, there were 101 in the MMCR group and 34 in the ELR group. Baseline mean MRD was 1.4mm in the MMCR group and 1.0mm in the ELR group(p<0.05). At the early postoperative visit, mean MRD was 2.3mm in the MMCR group and 2.8mm in the ELR group(p<0.05). At the late postoperative visit, mean MRD was 3.0mm in the MMCR group and 3.0mm in the ELR group(p>0.05). Change in MRD from baseline to early postoperative visit was greater after ELR(1.81mm vs. 0.88mm, p<0.05). Change in MRD from the early postoperative to the late postoperative visit was greater with MMCR(0.75mm vs. 0.26mm, p<0.05).
Repeated measures ANOVA confirmed the interaction of group and time(p<0.05), indicating that change over time was significantly different for ELR vs. MMCR(Figure 1). For the secondary outcome, the proportion of subjects with minimal(<0.05mm) change from the baseline to early postoperative visit was significantly(p<0.05) lower in the ELR group 11.8%) relative to the MMCR group(40.6%).
Conclusions :
ELR and MMCR can effectively elevate the eyelid and have similar late postoperative results. This study shows that MMCR cases undergo greater change between the early and late postoperative period, suggesting that the process of lid elevation in MMCR is more dynamic than in ELR. This supports the contention that MMCR and ELR surgery may act through different mechanisms.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.