37 Anterior Orbitotomy
An anterior orbitotomy is a broad term to indicate entry into the orbit, generally to the orbit anterior to the equator of the globe. A multitude of techniques are available, and the ones discussed here are extensions of commonly used incisions fundamental to oculofacial plastic surgery. Access to the posterior orbit can be achieved with modification of the described techniques. In this chapter, we organize approaches based on location of the orbit: superior, inferior, lateral, and medial.
The goals of the surgery are dependent on the problem being addressed, which is determined prior to surgery. In general, surgery performed should provide adequate access and visualization of the area, should minimize the risk of damage to the surrounding structures, and leave minimal visible scars. Preoperative planning should incorporate a detailed medical history, examination, and imaging to formulate a differential diagnosis. An anterior orbitotomy is performed to access areas anterior to the equator of the globe. Isolated, well-circumscribed lesions may warrant total excisional biopsy while infiltrative lesions may warrant incisional biopsy for tissue diagnosis. Anteriorly positioned abscesses can be evacuated via different anterior orbitotomy approaches.
Many of the anterior orbitotomy approaches are extensions of common incisions used in oculoplastic surgery. Some of these approaches can also be used to access the posterior orbit. These incisions are commonly placed in areas that heal with imperceptible or minimal scarring.
With correct selection of biopsy location, surgeons should expect excellent access to the relevant portion(s) of the orbit with minimal risk of damage to surrounding structures.
37.4 Key Principles
Preoperative determination of the location of the lesion guides the anterior orbitotomy approach (Fig. 37‑1). Lesions located in the superior orbit can be accessed by an eyelid crease, subbrow, eyelid split, or fornix approach. The medial orbit can be accessed by a transcaruncular, transconjunctival, or Lynch incision. Lesions in the inferior orbit can be accessed by an external transcutaneous approach such as a subciliary, lower eyelid crease; direct orbital rim incision; or internal transconjunctival approach such as a conjunctival or fornix incision. The lateral orbit is typically accessed with a canthotomy and cantholysis (e.g., swinging eyelid incision). This may be necessary for lesions more posteriorly located in the orbit or for placement of large orbital implants.
Combined approaches (inferior fornix + swinging eyelid) are useful for large lesions that span two spaces (e.g., the inferior and lateral orbit). Accessing the subperiosteal location may be more easily achieved with certain approaches (e.g., subbrow or eyelid crease incision vs. superior fornix approach).
37.4.2 Well-Hidden Incisions
Although cosmesis is not the primary goal of orbitotomy procedures, utilization of approaches close to the lesion that hide incisions can lead to superior results without compromising access. Choices include the upper eyelid crease, palpebral conjunctiva, subciliary line, and subciliary brow.
By utilizing an approach where the incision hides well allows the surgeon to comfortably create a wide incision for improved surgical exposure. When working deep in the orbit, maintaining a wide superficial incision improves visualization. Retraction of superficial structures with skin hooks, Desmarres retractors, and traction sutures and deeper structures with Sewall or malleable retractors helps exposure and dissection. Care should be taken to avoid prolonged or high pressure on the globe during retraction.
A dry field makes exposing and removing an orbital lesion more manageable. Additionally, blood pressure, pain, and nausea should be well controlled during and after surgery. Herbal medications and supplements such as gingko biloba, vitamin E, and ginseng should be discontinued preoperatively. Intraoperative techniques to help control hemostasis include reverse Trendelenburg positioning, epinephrine injection (care should be taken to monitor for rebound bleeding after effects of epinephrine wear off), bipolar cauterization, and platelet-activating products such as absorbable gelatin (Gelfoam), oxidized regenerated cellulose (Surgicel), and thrombin (FloSeal). Paraffin wax can be useful for bony bleeding, although there are reports of retained wax causing granuloma formation or infection. 1 Cool compresses and gentle pressure are time tested and also well tolerated, if applied with caution (i.e., avoid prolonged ice packs or excessive pressure). Intraoperative packing, such as neurosurgical patties, soaked with epinephrine-containing products can be used, but care should be taken to avoid excessive pressure, blood pressure changes with epinephrine, and retained packing material.
Anterior orbitotomy is indicated for access to lesions anterior to the equator of the globe. This may include the excision of orbital masses, incisional biopsies, drainage of abscesses, and removal of foreign bodies.
Contraindications to surgery are decided on a case-to-case basis. In general, access to deep orbital lesions may not be accessible with some approaches discussed here (see individual sections for more detail). An approach that does not provide adequate exposure to visualize the surgical target or control bleeding is another relative contraindication.
37.7 Preoperative Preparation
The patient should be cleared medically prior to proceeding with surgery. Blood pressure should be controlled. Preoperative risk stratification and assessment for the possibility of discontinuing blood thinners perioperatively should be done in conjunction with the patient’s primary care physician. Elective procedures should be avoided if blood thinners cannot be stopped. Herbal remedies (such as the ones discussed earlier) should also be discontinued.
The risks of the procedure should be thoroughly discussed and documented. In general, risks for anterior orbitotomies include infection, pain, postoperative edema and ecchymosis, ptosis, lagophthalmos, diplopia, and rarely postoperative orbital hemorrhage that can lead to permanent blindness. Rare complications include infection, orbital compartment syndrome, cerebrospinal fluid leak, or blindness.
37.8 Operative Technique
37.8.1 Superior Orbit
Upper Eyelid Crease Approach
This approach has the advantage of a cosmetically well-hidden incision (Fig. 37‑2a). It can be used to access the superior orbit either through the septum or the superior subperiosteal space.
The patient is placed under local or general anesthesia. Corneal protectors are placed. The upper eyelid crease is demarcated with a marking pen. Local anesthesia (admixture of lidocaine and bupivacaine with 1:100,000 parts epinephrine) is infiltrated into the upper eyelid. An incision is made along the marked line sufficiently long for adequate exposure of the lesion. The orbicularis oculi muscle is then incised to expose the orbital septum. Meticulous hemostasis should be maintained. Once the septum is exposed, retractors (e.g., skin hooks) are centered over the lesion. Finger palpation of the lesion can help with localization. After horizontal incision through the septum, blunt dissection can locate, isolate, and remove the lesion. If the goal is an incisional biopsy, sufficient tissue for diagnosis should be removed. Clear communication with the pathologist including relevant history, clinical findings, and differential diagnosis is important for accurate diagnosis.
The subperiosteal space can be accessed through this same incision. After the incision is made in the orbicularis muscle, a preseptal dissection plane is carried superiorly to the orbital rim, where sharp dissection can be carried to the periosteum. The periosteum overlying the frontal bone can then be incised and elevated to the arcus marginalis. Then, the superior subperiosteal space of the orbit is entered. Aggressive dissection at the arcus marginalis should be avoided, as periosteal violation can allow orbital fat to herniate into the field, limiting visualization. The eyelid crease incision can be extended medially, but should not cross any epicanthal folds or the medial canthal tendon, as contracture and formation of a medial canthal web may occur. In the superomedial orbit, there are numerous neurovascular structures (supraorbital bundle, supratrochlear bundle, trochlea, superior oblique) that should not be disrupted, if possible.
Subbrow Approach (Superior Subperiosteal Approach)
A subbrow approach can be used as a more direct approach to the superior subperiosteal plane or to access to the frontal bone for procedures such as mucocele removal, frontal sinus access, or limited frontal craniotomy (Fig. 37‑2b). This incision increases the chance of visible cutaneous scar, although placement of the incision adjacent to the cilia of the brow makes it generally well accepted.
The supraorbital notch is palpated at the medial superior rim and marked to avoid inadvertent injury to the supraorbital neurovascular bundle. Following infiltration with local anesthetic, this incision is made in the skin at the inferior brow cilia. Dissection is carried down to the periosteum about 5 mm superior to the orbital rim. An incision is then made through the periosteum using a blade or Freer elevator, and the periosteum is elevated off of the rim. The subperiosteal dissection continues inferiorly detaching the arcus marginalis and entering the superior subperiosteal space in the orbit. After completion of surgery, the periosteum may be closed with interrupted absorbable sutures, and the skin can be closed with interrupted absorbable sutures.
37.8.2 Inferior Orbit
Lower Eyelid Transcutaneous Approach
Inferior orbital lesions in the extraconal space can be approached via the subciliary skin or the inferior palpebral conjunctiva. These offer excellent exposure to the orbit with low risk of postoperative eyelid malposition or visible scar. The lower eyelid crease incision or direct rim incision have been described; however, they routinely lead to disfiguring scars, and offer few advantages to the other access points (Fig. 37‑3).
The area can also be accessed by a conjunctival approach. An incision can be made a few millimeters inferior to the inferior tarsal border or it can be made in the fornix. These internal approaches generally give good cosmesis. Occasionally, releasing the capsulopalpebral fascia can lead to lower lid entropion or ectropion in those who already have eyelid laxity.