CHAPTER 7

Orbital Surgery

Orbital surgery requires the delicacy of a neurosurgeon, the strength of an orthopedic surgeon, and the 3-dimensional sense of a general surgeon. Few other locations of the body have so many surgical spaces and so many vital structures within such a small area. Surgical comfort and success are based on the surgeon’s knowledge of the relationships among the orbital structures and ability to approach the orbit from different directions and angles to achieve the best access to the pathology.

Surgical Spaces

There are 5 surgical spaces within the orbit (Fig 7-1):

Figure 7-1 Surgical spaces of the orbit. A, Axial view. B, Coronal view. (Illustration by Cyndie C. H. Wooley.)

the subperiosteal (subperiorbital) surgical space, which is the potential space between the bone and the periorbita

the extraconal surgical space (peripheral surgical space), which lies between the periorbita and the muscle cone with its fascia

the sub-Tenon (episcleral) surgical space, which lies between the Tenon capsule and the globe

the intraconal surgical space (central surgical space), which lies within the muscle cone the subarachnoid surgical space, which lies between the optic nerve and the nerve sheath

A single orbital lesion may involve more than 1 surgical space, and a combination of approaches may be necessary for pathologic processes affecting the orbit. The approaches to these spaces—superior, inferior, medial, and lateral—are discussed in the following sections. Incisions used to reach these surgical spaces are shown in Figure 7-2.

Figure 7-2 Sites of surgical entry into the orbit. A, Classic Stallard-Wright lateral orbitotomy. B, Eyelid crease lateral orbitotomy. C, Lateral canthotomy/cantholysis orbitotomy. D, Transcaruncular medial orbitotomy. E, Frontoethmoidal (Lynch) medial orbitotomy. F, Upper eyelid crease anterior orbitotomy. G, Vertical eyelid split superomedial orbitotomy. H, Medial bulbar conjunctival orbitotomy. I, Subciliary inferior orbitotomy. J, Transconjunctival inferior orbitotomy. K, Lateral bulbar conjunctival orbitotomy. (Illustration by Christine Gralapp after a drawing by Jennifer Clemens.)

Orbitotomy

Superior Approach

More orbital lesions are found in the superoanterior part of the orbit than in any other location. Lesions in this area can usually be reached through a transcutaneous incision. With this approach, the surgeon must take care to avoid damaging the levator muscle, superior oblique muscle, trochlea, lacrimal gland, and sensory nerves and vessels entering or exiting the orbit along the superior orbital rim.

Transcutaneous incisions

For procedures in the superior subperiosteal space, an incision through the upper eyelid crease offers good access to the superior orbital rim and periosteum, with a well-hidden scar (Fig 7-3). Although this incision requires additional soft tissue dissection, the cosmetic result is better with an eyelid crease incision than with an incision directly over the superior orbital rim. After making an upper eyelid crease incision, the surgeon obtains access to the superior orbital rim by dissecting superiorly in the postorbicularis fascial plane anterior to the orbital septum. After the rim is exposed, an incision is made in the arcus marginalis of the rim, and a periosteal elevator is then used to separate the periosteum from the frontal bone of the orbital roof. The periosteal dissection is facilitated by initially keeping the periorbita intact, which prevents orbital fat from obscuring the view during reflection of the periosteum.

Vertical splitting of the upper eyelid at the junction of the medial and central thirds allows extended transconjunctival exposure for the removal of superomedial intraconal tumors. The surgeon incises the eyelid and levator aponeurosis vertically to expose the superomedial intraconal space. Realignment of the tarsal plate and aponeurosis with vertical closure prevents postoperative ptosis and eyelid retraction.

Kersten RC, Kulwin DR. Vertical lid split orbitotomy revisited. Ophthal Plast Reconstr Surg. 1999;15(6):425–428.

Inferior Approach

The inferior approach is suitable for masses that are visible or palpable in the inferior conjunctival fornix of the lower eyelid, as well as for deeper inferior extraconal orbital masses. The surgeon can also gain access to intraconal lesions by dissecting between the inferior rectus and lateral rectus muscles. The inferior oblique muscle inserts over the macula and may be identified and retracted while intraconal lesions are accessed. This route is commonly used to approach the orbital floor for fracture repair or decompression.

Transcutaneous incisions

Visible scarring can be minimized by the use of an infraciliary blepharoplasty incision (2.5–4.0 mm below the margin) in the lower eyelid skin, followed by inferior dissection beneath the orbicularis oculi muscle to expose the inferior orbital septum and inferior orbital rim. An incision in the lower eyelid crease or directly over the inferior orbital rim can provide similar exposure, but it leaves a slightly more obvious scar. Once the skin–muscle flap is created, the surgeon can open the septum to expose the extraconal surgical space. Alternatively, for access to the inferior subperiosteal space the periosteum is incised and elevated at the arcus marginalis to expose the orbital floor. Fractures of the orbital floor are reached by the subperiosteal route.

Transconjunctival incisions

The transconjunctival approach (Fig 7-4) has largely replaced the transcutaneous route for exposure of tumors in the inferior orbit and for management of fractures of the orbital floor and medial wall. To reach the extraconal surgical space and the orbital floor, the surgeon may make an incision through the inferior conjunctiva and lower eyelid retractors. The optical cavity can be enlarged by adding a lateral canthotomy and cantholysis. The transconjunctival incision is made either just below the inferior tarsal border or in the conjunctival fornix. When using cutting cautery, the surgeon should take care not to cause thermal damage to the conjunctiva and tarsus. Opening the reflected periosteum and then retracting the muscles and intraconal fat provide access to not only the orbital floor but also the intraconal space.

An incision in the bulbar conjunctiva allows entry into the extraconal or sub-Tenon surgical space. If the medial rectus muscle is detached, the surgeon can then enter the intraconal surgical space to expose the region of the anterior optic nerve for examination, biopsy, or sheath fenestration (Fig 7-5). If the posterior optic nerve or muscle cone needs to be seen well, a combined lateral/medial orbitotomy can be performed. A lateral orbitotomy with removal of the lateral orbital wall allows the globe to be displaced temporally, thus maximizing medial access to the deeper orbit.

Figure 7-5 Medial transconjunctival approach for optic nerve sheath fenestration. The medial rectus muscle has been disinserted. There is a traction suture at the muscle insertion site to rotate the globe, and the muscle is imbricated with a suture. (Courtesy of Morris E. Hartstein, MD.)

Transcaruncular incision

An incision through the posterior third of the caruncle allows excellent exposure of the medial periosteum. Blunt dissection carried medially, just posterior to the lacrimal sac, allows access to the subperiosteal space along the medial wall. Incision and elevation of the medial periorbita allow exposure of the medial orbital wall. This incision has the advantage of providing better cosmetic results than the traditional Lynch, or frontoethmoidal, incision, but the surgeon must be careful to protect the lacrimal canaliculi and to remain posterior to the lacrimal apparatus. The combination of the transcaruncular route with an inferior transconjunctival incision allows extensive exposure of the

inferior and medial orbit. This approach provides access for repair of medial wall fractures, for medial orbital bone decompression, and for drainage of medial subperiosteal abscesses.

Goldberg RA, Mancini R, Demer JL. The transcaruncular approach: surgical anatomy and technique. Arch Facial Plast Surg. 2007;9(6):443–447.

Lateral Approach

A lateral orbitotomy approach is used when a lesion is located within the lateral intraconal space, behind the equator of the globe, or in the lacrimal gland fossa. As the orbits are relatively shallower in children than in adults, extensive exposure of the orbits without the need for bone removal may be possible in children. The traditional S-shaped Stallard-Wright skin incision (see Fig 7-2), extending from beneath the eyebrow laterally and curving down along the zygomatic arch, allowed good exposure of the lateral rim but left a noticeable scar. It has largely been replaced by approaches through either an upper eyelid crease incision or an extended lateral canthotomy incision. Both of these approaches allow exposure of the lateral orbital rim and anterior portion of the zygomatic arch after reflection of the temporalis muscle and the periosteum of the orbit. Dissecting through the periorbita and then intermuscular septum either above or below the lateral rectus muscle and posterior to the equator of the globe provides access to the intraconal retrobulbar space. The retrobulbar optic nerve may be reached this way and fenestrated in cases of idiopathic intracranial hypertension.

If a lesion cannot be adequately exposed through a soft tissue lateral incision, an oscillating saw is used to remove the bone of the lateral rim to expose the underlying periorbita, which is then opened. An operating microscope is often useful during intraorbital surgery, especially if dissection proceeds inside the muscle cone. Good exposure of the intraconal surgical space can be achieved with retraction of the lateral rectus muscle. Tumors can occasionally be prolapsed into the incision by application of gentle pressure over the eyelids. A cryosurgical probe or Allis forceps can be used to provide firm traction on encapsulated tumors. In cavernous hemangiomas, a suture through the lesion allows not only traction but also slow decompression of the tumor to facilitate its removal.

Complete hemostasis should be accomplished before closure. To help prevent postoperative intraorbital hemorrhage, an external drain may be placed through the skin to reach the deep orbital tissues. The lateral orbital rim is usually replaced and may be sutured back into place through predrilled tunnels in the rim. Alternatively, the surgeon may use rigid fixation with plating systems. The overlying tissues are then returned to their normal positions and sutured. The use of steel wire is avoided because it can cause artifacts on follow-up computed tomography scans. The surgeon closes the periosteum loosely to allow postoperative hemorrhage to decompress.

Kersten RC, Kulwin DR. Optic nerve sheath fenestration through a lateral canthotomy incision. Arch Ophthalmol. 1993;111(6):870– 874.

Orbital Decompression

Orbital decompression is a surgical procedure used to improve the volume-to-space discrepancy that occurs primarily in thyroid eye disease (TED). The goal of orbital decompression is to allow the enlarged muscles and orbital fat to expand into the additional space that has been created by the surgery (Fig 7-6). This expansion relieves pressure on the optic nerve and its blood supply and reduces proptosis.

Figure 7-6 Potential sites for orbital decompression include the medial wall (blue), lateral wall (yellow), and floor of the orbit

(orange).(Courtesy of Bobby S. Korn, MD, PhD.)

Decompression historically involved removal of the medial orbital wall and much of the orbital floor to allow orbital tissues to expand into the ethmoid and maxillary sinuses. The approach was made through the maxillary sinus (Caldwell-Luc) or transcutaneous anterior orbitotomy incision. However, when used in patients with inflammatory eye disease featuring enlarged, restricted inferior rectus muscles, this type of decompression with removal of the medial orbital strut may result in or exacerbate globe ptosis and upper eyelid retraction and disrupt globe excursion due to prolapse of the muscles into the ethmoid or maxillary sinuses and displacement of the orbital contents. The approach currently used by many orbital surgeons is a transconjunctival incision combined with a lateral canthotomy/cantholysis to evert the lower eyelid for exposure of the inferior and lateral orbital rims (Fig 7-7). Extension of this incision superonasally with a transcaruncular approach allows excellent access to the medial orbital wall for bone removal and decompression. (A transnasal endoscopic approach to the medial orbit via the ethmoid sinus may also be useful for the medial wall.) To allow further decompression into the infratemporal fossa, the surgeon may remove the lateral orbital rim and reposition it anteriorly at the time of closure. Anterior displacement of the lateral canthus may also aid in the reduction of eyelid retraction. Burring down the orbital surface of the lateral wall and the sphenoid wing results in additional decompression. This type of procedure maximizes volume expansion and “balances” the decompression (Fig 7-8).

Figure 7-7 Surgical approach to the orbit combining lateral canthotomy/cantholysis, inferior transconjunctival incision, and medial Lynch (frontoethmoidal) incision. Lateral orbital rim bone removed. (Courtesy of Jill Foster, MD.)

Kacker A, Kazim M, Murphy M, Trokel S, Close LG. “Balanced” orbital decompression for severe Graves’ orbitopathy: technique with treatment algorithm. Otolaryngol Head Neck Surg. 2003;128(2):228–235.

Perry JD, Kadakia A, Foster JA. Transcaruncular orbital decompression for dysthyroid optic neuropathy. Ophthal Plast Reconstr Surg. 2003;19(5):353–358.

White WA, White WL, Shapiro PE. Combined endoscopic medial and inferior orbital decompression with transcutaneous lateral orbital decompression in Graves’ orbitopathy. Ophthalmology. 2003;110(9):1827–1832.

Postoperative Care for Orbital Surgery

Measures used to reduce postoperative edema are elevation of the head, iced compresses on the eyelids, administration of systemic steroids, and optional placement of a drain (if used, the drain is removed in 24–48 hours). Visual acuity is checked in the first 12 hours after surgery. Systemic antibiotics may be given. Ice packs minimize swelling and still allow frequent observation of the operative site and vision monitoring.

Special Surgical Techniques in the Orbit

Fine-needle aspiration biopsy (FNAB) may have value in selected cases of lymphoid lesions, secondary tumors invading the orbit from the sinuses, suspected metastatic tumors, and blind eyes with optic nerve tumors. The technique is not very effective for obtaining tissue from fibrous lesions because of the difficulty in successfully aspirating cells. Although FNAB has not been considered a good technique for biopsy in lymphoproliferative disorders, it may assist in the diagnosis of selected cases when used with flow cytometry with monoclonal antibodies or polymerase chain reaction analysis. FNAB is performed with a 4-cm 22or 23-gauge needle attached to a syringe in a pistol-grip syringe holder. If necessary, the needle can be guided into the tumor by ultrasonography or computed tomography. Cells (and occasionally a small block of tissue) are aspirated from the lesion. A skilled cytologist is required to study the specimen. See BCSC Section 4, Ophthalmic Pathology and Intraocular Tumors, for further discussion of FNAB.

Masses or traumatic injuries may involve the skull base, including posterior and superior aspects of the orbit. Advanced surgical techniques provide access to these areas via a frontal craniotomy or frontotemporal-orbitozygomatic approach. Such operations often require the combined efforts of the orbital surgeon, neurosurgeon, and otorhinolaryngologist. The neurosurgeon provides orbital access for the oculofacial surgeon by removing the frontal bar and the orbital roof, giving unparalleled access to superior apical lesions. These techniques allow removal of tumors such as meningiomas, fibrous dysplasia, hemangiomas, hemangiopericytomas, schwannomas, and gliomas that might not otherwise be resectable. In addition, the frontotemporal-orbitozygomatic approach provides access to the intracranial optic canal for decompression.

McDermott MW, Durity FA, Rootman J, Woodhurst WB. Combined frontotemporal-orbitozygomatic approach for tumors of the sphenoid wing and orbit. Neurosurgery. 1990;26(1):107–116.

Complications of Orbital Surgery

The surgeon can reduce complications from orbital surgery by performing a complete preoperative evaluation with orbital imaging when indicated, choosing the appropriate surgical approach, obtaining adequate exposure, carefully manipulating the tissues, employing proper instrumentation and illumination, maintaining good hemostasis, and using a team approach when appropriate.

Decreased or lost vision is a serious complication of surgery that may be caused by excessive traction on the globe and optic nerve, contusion of the optic nerve, postoperative infection, or hemorrhage,

which leads to increased orbital pressure and consequent ischemic injury to the optic nerve. A patient who has severe orbital pain postoperatively should be evaluated immediately for possible orbital hemorrhage. If this pain is associated with decreased vision, proptosis, ecchymosis, increased intraocular pressure, and an afferent pupillary defect, the surgeon should consider opening the wound to minimize the effects of the compartment syndrome (see Chapter 6), evacuating any hematoma, and controlling active bleeding.

Hypoesthesia in the distribution of the infraorbital nerve may follow manipulation of the orbital floor after fracture repair or orbital floor decompression. Other complications of decompression, such as downward displacement of the globe and postoperative exacerbation of upper eyelid retraction, were discussed previously. Motility disorders may be caused or exacerbated by orbital surgery. The active, or inflammatory, phase of TED may increase the risks of postoperative restrictive myopathy and enlarged muscle displacement in orbital decompression. In tumor resection in the superior orbit, the superior division of the third cranial nerve is especially susceptible to intraoperative injury. The ciliary ganglion is at risk in lateral approaches to the intraconal space. Other complications of orbital surgery include ptosis, neuroparalytic keratopathy, pupillary changes, vitreous hemorrhage, detached retina, hypoesthesia of the forehead, keratitis sicca, cerebrospinal fluid leak, and infection.

Purgason PA, Hornblass A. Complications of surgery for orbital tumors. Ophthal Plast Reconstr Surg. 1992;8(2):88–93.