Fig. 6.1
Frontal view of the left periocular area with the superficial layers (eyelid skin and orbicularis oculi) removed. The medial and lateral canthal ligaments attach the eyelids to the orbital walls. The lateral canthal angle is about 2 mm higher than the medial canthal angle. The upper eyelid covers the superior limbus by about 2 mm in adults. A Superficial limb of the medial canthal ligament. B Deep limb of the medial canthal ligament. C Medial canthal angle. D Superior tarsus. E Lateral canthal angle; F Lateral canthal ligament
The eyelid margin is divided into the anterior and posterior lamella by the gray line, the terminal extension of the orbicularis oculi muscle. The anterior lamella consists of the skin, orbicularis oculi muscle and the eyelashes. The posterior lamella includes the tarsus and the conjunctiva (Fig. 6.2). The canaliculi of the lacrimal drainage system are found in the medial portion of the upper and lower eyelids, and the puncta are located in the medial eyelid margins.
Fig. 6.2
Anterior and posterior lamella of the eyelid margin separated by the gray line. Anterior lamella includes the eyelid skin, orbicularis oculi muscle and the cilia. Posterior lamella includes the tarsus and the palpebral conjunctiva. A Gray line. B Meibomian gland orifice. C Meibomian gland. D Tarsus. E Palpebral conjunctiva. F Cilia. G Eyelid skin. H Orbicularis oculi muscle
The eyelid skin is the thinnest skin of the body. Careful repair of an eyelid skin laceration usually produces minimal scarring and cosmetically favorable results. There is loose subcutaneous tissue with minimal subcutaneous fat in this region.
The orbicularis oculi muscle is a superficial muscle covering the orbit and is found just posterior to the eyelid. It is innervated by the facial nerve and its main actions are involuntary blink and forced eyelid closure. Portions of the muscle surrounding the canaliculi participate in the lacrimal pump mechanism allowing egress of tears through the lacrimal outflow system.
Posterior to the orbicularis oculi muscle is the orbital septum, a thin membrane that arises from the periosteum of the orbital rim and marks the anterior border of the orbit. In the upper eyelid it fuses with the underlying levator aponeurosis 2–5 mm above the superior border of the tarsus. In the lower eyelid it inserts on the inferior border of the tarsus along with the lower eyelid retractors [1]. The septum is an important barrier protecting the vital orbital compartment and its structures from spread of infection or blood in cases of preseptal cellulitis or hemorrhage. Orbital fat, including the preaponeurotic and the lower eyelid fat pads, are found directly posterior to the septum.
The muscles that elevate the upper eyelid and depress the lower eyelid are called the eyelid retractors (Fig. 6.3). They are found deep to the orbital fat and include the levator palpebrae superioris and Müller’s muscle in the upper eyelid and the lower eyelid retractors in the lower eyelid. The retractors of the upper eyelid are more developed than their counterparts in the lower eyelid because the upper eyelid requires greater range of motion.
Fig. 6.3
Cross-section of the upper eyelid. A Eyelid skin. B Orbicularis oculi muscle. C Orbital septum. D Preaponeurotic orbital fat. E Levator palpebrae superioris muscle. F Müller’s muscle. G Levator aponeurosis. H Palpebral conjunctiva. I Tarsus
The levator palpebrae superioris is innervated by the oculomotor nerve and is the main elevator of the upper eyelid. It arises in the posterior orbit in the orbital apex and travels anteriorly through the superior orbit. Near the superior orbital rim a fibrous condensation, Whitnall’s ligament, is attached to the levator muscle sheath transversely and redirects the course of the muscle inferiorly. At Whitnall’s ligament, the muscular body of the levator changes to the fibrous levator aponeurosis. The levator aponeurosis inserts at the anterior surface of the tarsus, with other distal attachments to the overlying orbicularis oculi muscle and skin forming the upper eyelid crease. Medially and laterally the levator aponeurosis attaches to the bony orbit. The lateral horn of the aponeurosis divides the lacrimal gland into the orbital and palpebral lobes as it passes toward the lateral orbital wall.
Müller’s muscle is sympathetically innervated and contributes 2 mm of elevation to the upper eyelid. It arises from the underside of the levator muscle in the superior orbit and inserts at the superior border of the tarsus. The lower eyelid retractors arise from the capsulopalpebral fascia and insert into the inferior border of the lower lid tarsus. Just posterior to Müller’s muscle in the upper lid, and the lower eyelid retractors in the lower lid, is the palpebral conjunctiva.
The tarsal plates and the palpebral conjunctiva comprise the posterior lamella of the eyelid. The tarsal plates contribute to the form and support of the eyelids. Centrally, the upper tarsus is 10 mm in height, while the lower tarsus is 3–5 mm [1]. It is composed of dense connective tissue and contains sebaceous meibomian glands. The glands secrete the oily component of the tear film with their orifices located at the eyelid margin. The palpebral conjunctiva is adherent to the posterior tarsal surface and extends over the eyelid margin to the mucocutaneous junction, just posterior to the meibomian gland orifices. This conjunctiva represents a smooth mucous membrane important for comfortable contact between the lid and globe during the blink cycle and eye movements.
The tarsal plates are attached to the bony orbit by fibrous connections called the medial and lateral canthal ligaments (Fig. 6.1). The medial canthal ligament consists of a superficial and deep limb, which attach to the anterior and posterior lacrimal crest, respectively. The posterior attachment is important in maintaining the apposition of the eyelids against the convex globe and allowing normal tear drainage. Disruption of this anatomic relationship by trauma can result in chronic tearing (epiphora). Laterally, the fibrous strands from the tarsal plates form a common lateral canthal ligament, which attaches just inside the lateral orbital rim at the lateral orbital tubercle. It is important to recreate this posterior insertion during reconstruction after lateral canthal avulsion injuries.
The eyelids have a rich vascular supply that promotes healing. This includes an extensive network of anastomoses between branches from the external and internal carotid arteries. The angular and the superficial temporal arteries from the external carotid and the ophthalmic artery and its terminal branches from the internal carotid participate in this vascular network. They form the marginal and the peripheral arcades in the upper eyelid. The marginal arcade is found 2–4 mm superior to the eyelid margin, while the peripheral arcade is located at the superior tarsal border between the levator aponeurosis and Müller’s muscle [1]. The lower eyelid often has one arcade.
The eyelids are supplied by two sensory nerves, the ophthalmic and maxillary divisions of the trigeminal nerve. Sensory input travels from the upper eyelid via the ophthalmic division and from the lower eyelid via the maxillary division of the trigeminal nerve.
Eyelid Trauma
Evaluation
It is important to elicit a detailed history of the trauma when possible. The mechanism and timing of injury can provide clues as to whether deeper ocular or orbital damage has occurred or when the presence of a foreign body should be suspected. A penetrating injury with a long, sharp object can appear as a small puncture wound on the surface, but may extend deep into the orbit or globe causing significant damage. Lacerations due to bites have a higher prevalence of canalicular involvement than those due to other causes [2–4]. An orbital fracture should be considered in cases of blunt injury to the periorbital area.
A careful and systemic ocular and adnexal examination should be performed with the goal of determining the extent of injury. The examination of the eye should be performed first to exclude the presence of a serious ocular injury, such as a ruptured globe, that can be exacerbated by manipulation of the surrounding soft tissues. Often eyelid injuries coexist with severe ocular injuries that need to be addressed first to decrease the risk of potential vision loss [5]. Next, the eyelid should be examined. Careful cleaning of the traumatic area with saline and gauze will often uncover a more complex injury than was suspected during initial gross inspection as recent lacerations may splay apart disclosing their true extent. Careful inspection of the eyelid margin is critical in assessing margin involving full thickness lacerations. Special attention should be directed at the eyelid margins medial to the puncta to determine whether the canaliculi have been injured. If there is any suspicion, a lacrimal probe should be used to inspect for a canalicular laceration. The presence of orbital fat in a wound confirms that the orbital septum has been violated and trauma extends to orbital structures. Careful inspection of any deep wounds should be carried out using cotton tipped applicators to assess for presence of foreign bodies. Movement of the upper eyelid should be evaluated in a vertical direction to assess levator function. Based on the history and physical examination, orbital imaging may be warranted.
Management
Intravenous antibiotics should be administered if the injury is extensive or the wound appears contaminated. A history of tetanus immunization should be obtained. Human tetanus immunoglobulin 250 units should be administered unless the patient is up to date with this vaccination. If the patient’s immunization was more than 5 years ago, 0.5 mL of tetanus toxoid prophylaxis should be given [2].
Primary repair of eyelid wounds produces the best functional and cosmetic results. It is recommended that eyelid lacerations be repaired within 12–24 h of trauma; however, life and vision-threatening conditions should be addressed first. If a delay occurs, all attempts should be made to perform delayed primary closure rather than allowing the wounds to heal by secondary intention. Eyelid lacerations can be repaired after 24–72 h without significant negative outcomes, though the wound margins may have to be freshened during repair [2]. While awaiting repair, tissues should be repositioned into their anatomic locations and a robust supply of ophthalmic antibiotic ointment placed over the wounds. Systemic antibiotics should also be considered.
Repair can be performed using local anesthesia at bedside or in a minor procedure room for most minor injuries. More extensive injuries can be repaired in the operating room under sedation or general anesthesia. Local anesthesia can be achieved by injecting 1% lidocaine with 1:100,000 epinephrine. The authors prefer to combine lidocaine in a 50:50 mixture with 0.5% bupivacaine with epinephrine for a longer lasting effect and postoperative pain control. Betadine should be used to prep the surgical area. As always, consider medication allergies.
The first step in surgical repair is thorough cleaning and exploration of the wounds. To avoid chronic infection and abscess formation, removal of foreign bodies is essential. Avoid excising any tissue unless clearly devitalized. Decontamination of wounds using high-pressure sterile saline irrigation reduces the rate of wound infection by 90% [2]. If the wounds are visibly contaminated, irrigation with an antibiotic solution should also be performed.
When planning surgical repair, any injuries to the lacrimal apparatus, canthal ligaments, or the levator aponeurosis should be addressed first, and repair of eyelid margin and skin should follow. It may seem as if tissue is missing from a wound but this is uncommon in eyelid lacerations, and the appearance may actually be due to swelling and retraction of the wound edges. Care should be taken to carefully reapproximate the wound margins, unfolding any rolled tissue edges. Identifying landmarks such as the eyebrow hairline can help in proper realignment of the tissue. It is important not to mistakenly capture the septum during wound closure, to avoid secondary lid retraction and lagophthalmos.
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