Senders, C. W., Tollefson, T. T., Curtiss, S., Wong-Foy, A., & Prahlad, H. (2010). Force requirements for artificial muscle to create an eyelid blink with eyelid sling. Archives of Facial Plastic Surgery, 12(1), 30-36.
Abstract
Objective
To determine the force requirements, optimal vector, and appropriate materials of a novel eyelid sling device that will be used to rehabilitate eyelid closure (blink) in congenital or acquired permanent facial paralysis with an artificial muscle.
Methods
The force required to close the eyelids in human cadavers (n = 6) were measured using a load cell system. The eyelid sling using either expanded polytetrafluoroethylene (ePTFE) or temporalis muscle fascia was implanted. The ideal vector of force and placement within the eyelid for a natural eyelid closure were compared.
Results
The eyelid sling concept was successful at creating eyelid closure in a cadaver model using an upper eyelid sling attached to the distal tarsal plate. Less force was necessary to create eyelid closure using a temporalis muscle fascia sling (627 ± 128 mN) than for the ePTFE eyelid sling (1347 ± 318 mN).
Conclusions
The force and stroke required to close an eyelid with the eyelid sling are well within the attainable range of the electroactive polymer artificial muscle (EPAM). This may allow the creation of a realistic and functional eyelid blink that is symmetric and synchronous with the contralateral, normally functioning blink. Future aims include consideration of different sling materials and development of both the EPAM device and an articulation between the EPAM and sling. The biocompatibility and durability studies of EPAM in a gerbil model are under way. The successful application of artificial muscle technology to create an eyelid blink would be the first of many potential applications.
Electroactive polymer artificial muscle (EPAM) is an emerging technology that has the potential to be used in rehabilitating facial movement in patients with paralysis. These electroactive polymers act like human muscles by expanding and contracting based on variable voltage input levels. Mimicry of diaphragm movement in a canine model has shown promise and has led to the examination of reanimating smaller muscle groups, such as those responsible for eyelid closure or facial expression. Conventional treatment of permanent facial paralysis has included a variety of surgical procedures that endeavor to recreate the form and function of the facial musculature. Management of inadequate eyelid closure in facial paralysis seeks to protect the eye from corneal ulceration or blindness. This study seeks to develop the protocol and device design for human implantation of EPAM to reproducibly create a long-lasting eyelid blink that will protect the eye and improve facial appearance.