Author’s Disclosure Block: Edsel Ing, none; Jooyoung Song, none; Hyun-Joong Chung, none

Abstract Body
Purpose: To develop a non-metallic, eyelid spring for patients with paralytic lagophthalmos. Study Design: Evolutionary (prototype)METHOD: Various designs for polymethylmethacrylate (PMMA) and polypropylene (Prolene) eyelid springs were tested. The size of the lid spring was determined from normal adults.Our presumptive target spring force was 12-14 milliNewtons corresponding to the gravitationalforce of a 1.2 g or 1.4 g gold weight. We conceptualized central placement of the plastic lid spring, without the temporal fixation of dental wire springs. RESULTS: We targetedspring heights of 16 mm unstressed and 11 mm compressed from the average open and closed central eyelid measurements in 20 normal adults.The "Z" and "M" spring shapes that werelaser cut from 1 mm PMMA sheets were prone to fracture; those cut from 2 mm PMMA sheets were too rigid. PMMA 1.5 mm coils did not have good elasticity. However, prolene suture loops had adequate elasticity to act as eyelid springs. Silicone sleeves and sutures maintained prolene loop integrity, unlike cyanoacrylate glue and heat.Theoretical force calculations on circular loops are challenging. Empirical compression testing on a milligram scale with different gauges of Prolene suggested that compression of a 3-0 prolene loop generated the appropriate force requirements.Cadaver studies support the viability of central placement of the prolne loop under the central septum and tarsus. CONCLUSION: Prolene eyelid springs in the central eyelid merit further investigation. Prolene is approved by Health Canada and used for silicone slings. Prolene isinexpensive, does not hamper MRI, and the loopswork independent of gravity (unlike gold weights) without requiring lateral bonyfixation. (CC-BY-NC-ND)