How to Repair Eyelid Lacerations

Eyelid lacerations are common in horses and should be regarded as surgical emergencies to prevent undesirable tissue devitalization, infection, scarring, corneal desiccation, and corneal ulceration. Lacerations usually can be repaired in the standing, heavily sedated horse. General anesthesia may be required when there is extensive trauma or with an unruly horse. Even when horses are not evaluated immediately after the trauma and infection may have begun, repair should always be attempted immediately and with minimal debridement to prevent further tissue damage. Although a complete ophthalmic examination should be performed in all horses with eyelid lacerations, ocular examination usually reveals a normal globe; however, it is not unusual to have two lacerations, with one being much smaller than the other. Lacerations usually are caused by nails and hooks protruding from boards in the barn or stall, from fence wire or tree branches, or from sharp metal protuberances in trailers. Unfortunately, even with extensive study of the horse’s surroundings, the cause of the laceration is rarely determined. An understanding of eyelid anatomy and physiology is imperative for proper surgical repair because of the importance of perfect alignment of the eyelid margin and the close proximity of sutures to the cornea. A normal eyelid margin is crucial for globe health. The eyelid margin prevents hair from contacting the cornea and allows the lids to have perfect contact with the corneal surface. This normal eyelid contact during blinking removes precorneal debris and spreads the tear film over the cornea to prevent desiccation. Under normal conditions, there are no hairs or cilia on the eyelid margin. Meibomian gland openings form a row of tiny spots along the lid margins. These glandular openings serve as an important landmark for the figure-eight suture. The haired eyelid skin is very thin, with no redundancy. The palpebral conjunctiva lines the bulbar side of the eyelid and is also very thin, approximately 10 cell layers thick. The tissue between the skin and the palpebral conjunctiva from superficial to deep contains the orbicularis oculi muscle, the stroma (which contains the levator palpebral superioris muscle in the upper lid), and thin, fibrous tissue referred to as the tarsus. For the purpose of this report the layers of the eyelid will be referred to as the skin, stroma, and conjunctiva. Whereas the muscles that open and close the eyelids are important physiologically, they are not easily visible when the eyelid is lacerated and do not require special attention during the repair. Knowledge of eyelid innervation is also important for laceration repair. A branch of the facial nerve (auriculopalpebral nerve) controls the orbicularis oculi muscle, which closes the eyelids. This nerve