The resection of orbicularis oculi muscle from the upper eyelid in experimental surgery on the monkey

The purpose of this study was to determine the maximum amount of orbicularis oculi muscle that may safely be resected from the upper eyelid without causing functional abnormalities. Measured amounts of that muscle were surgically excised from both upper eyelids in six cynomolgus monkeys. All the eyelids were photographed and videotaped at progressively increased intervals to permit the evaluation of wound healing, scarring, and function. Our preliminary results revealed that the excision of preseptal and partial supraorbital orbicularis oculi muscle, preseptal and complete supraorbital muscle, or pretarsal muscle only did not result in lagophthalmos. Complete resection of pretarsal, preseptal, and supraorbital orbicularis oculi did result in lagophthalmos but caused no corneal injury. The orbicularis oculi muscle in the cynomolgus monkey is similar to that in humans, but it is not yet clear whether our findings in the monkey are applicable in humans. A determination of the maximum amount of orbicularis oculi muscle that can safely be excised in humans would enable plastic surgeons to better understand and develop techniques for eyelid reconstruction and blepharoplasty.