Daniel B Rootman1,2, Kunal R Sinha2,3, Robert A Goldberg2. 1. Division of Orbital and Ophthalmic Plastic Surgery, Doheny Eye Center. 2. Division of Orbital and Ophthalmic Plastic Surgery, Stein Eye Institute. 3. David Geffen School of Medicine, University of California, Los Angeles, U.S.A.
Abstract
PURPOSE: This study compares the use of a standard 7 mm resection length to a variable 4:1 ratio of resection length to desired elevation nomogram when performing Muller's muscle conjunctival resection surgery. METHODS: In this cross-sectional case control study, 2 groups were defined. The first underwent Muller's muscle conjunctival resection surgery with a standard 7 mm resection length and the second underwent the same surgery with a variable resection length determined by a 4:1 ratio of resection length to desired elevation nomogram. Groups were matched for age (within 5 years) and sex. Pre- and postoperative photographs were measured digitally. Change in upper marginal reflex distance 1 (MRD1) and final MRD1 were the primary outcome measures. The study was powered to detect a 1 mm difference in MRD1 to a beta error of 0.95. RESULTS: No significant preoperative differences between the groups were noted. No significant difference in final MRD1 (0.1 mm; p = 0.74) or change in MRD1 (0.2 mm; p = 0.52) was noted. Mean resection length to elevation ratios were 3.9:1 for standard group and 4.3:1 for the variable group (p = 0.54). CONCLUSION: The authors were not able to detect a significant difference in final MRD1 or change in MRD1 for patients undergoing Muller's muscle conjunctival resection surgery with standard or variable resection lengths. These results tend to argue against a purely mechanical mechanism for Muller's muscle conjunctival resection surgery.
PURPOSE: This study compares the use of a standard 7 mm resection length to a variable 4:1 ratio of resection length to desired elevation nomogram when performing Muller's muscle conjunctival resection surgery. METHODS: In this cross-sectional case control study, 2 groups were defined. The first underwent Muller's muscle conjunctival resection surgery with a standard 7 mm resection length and the second underwent the same surgery with a variable resection length determined by a 4:1 ratio of resection length to desired elevation nomogram. Groups were matched for age (within 5 years) and sex. Pre- and postoperative photographs were measured digitally. Change in upper marginal reflex distance 1 (MRD1) and final MRD1 were the primary outcome measures. The study was powered to detect a 1 mm difference in MRD1 to a beta error of 0.95. RESULTS: No significant preoperative differences between the groups were noted. No significant difference in final MRD1 (0.1 mm; p = 0.74) or change in MRD1 (0.2 mm; p = 0.52) was noted. Mean resection length to elevation ratios were 3.9:1 for standard group and 4.3:1 for the variable group (p = 0.54). CONCLUSION: The authors were not able to detect a significant difference in final MRD1 or change in MRD1 for patients undergoing Muller's muscle conjunctival resection surgery with standard or variable resection lengths. These results tend to argue against a purely mechanical mechanism for Muller's muscle conjunctival resection surgery.