Ординатура / Офтальмология / Английские материалы / Orbital Tumors Diagnosis and Treatment_Karcioglu_2005

inferior vertical osteotomy

FIGURE 31.11. Lateral orbitotomy procedure. (A) Anchoring the lateral rectus muscle with a silk traction suture; a note lazy-S lid crease incision. (B) Spreading the wound with sharp and blunt dissection to reach to the underlying bone. (C) Cutting the periosteum

connecting the vertical osteotomies with a horizontal cut by chisel

and undermining the edges (arrowheads) to expose the bone. (D) Drilling holes into the zygomatic bone. (E) Cutting the zygomatic bone with an oscillating saw (OS). (F) Cutting the posterior aspect of the zygomatic bone with a chisel (Ch).

ticularly if the zygomatic arch is going to be left attached to the temporalis muscle, drilling of the bone just prior to repositioning may be cumbersome. Furthermore, a 3-0 Prolene traction suture can be passed through the holes of the cut piece and retracted posteriorly to keep the bone–muscle flap away from the surgical field (Figure 31.11). After all horizontal and vertical bone cuts have been completed, a large, frontbiting bone rongeur is placed on the zygomatic arch and the lateral orbital wall is out-fractured by bending the rongeur laterally and posteriorly. If there is resistance, the surgeon should extend the bony incisions rather than applying excessive force onto the bone, which may lead to irregular cracks into the orbit. The lateral rim of the orbit is cut but not totally removed from the surgical field; it is hinged laterally with a traction suture while it is still attached to the temporalis muscle. In a great majority of cases, this maneuver provides enough exposure of the surgical field.

Once the bone flap is out of the way and the surgeon is satisfied with the full exposure of the orbit,

periorbita is incised, generally, with one vertical cut. Periorbita should be cut with extreme care. It usually helps to hold it with a 0.5 or 0.9 forceps and make a shallow nick into it with a sickle-shaped no. 12 BardParker blade. When this has been accomplished, one blade of the blunt Stevens scissors is inserted under the periorbita and it is carefully cut. The initial placement of the nick with the scalpel should not be directly over the lateral rectus muscle.

Alternatively, the initial nick of the scalpel blade can be slightly enlarged with a small curved hemostat, which is then inserted underneath the periorbita for blunt dissection of the underlying fat and attachments. When this has been accomplished, the hemostat is pulled up to tent the periorbita, away from the lateral rectus muscle, which then can be cut safely with blunt Stevens scissors. The edges of periorbita may be tagged with silk sutures to facilitate its approximation at the closure. With the orbital surgical field exposed to the surgeon’s satisfaction, the exploration is carried out with the use of narrow ribbon re-

tractors, blunt microsurgical dissectors, small curved hemostats, and cotton tip applicators. At times a dual cotton tip holder may be positioned on each side of a tumor and by pushing this instrument posteriorly, one may break the adhesions to the lesion, whereupon the tumor may eventually come forward without too much damage to the surrounding tissues. This simple instrument (Figure 31.12D) is also very handy to stabilize the optic nerve during the sheath fenestration procedure.30 If the anterolateral presentation of the tumor does not happen readily, a fine-toothed Adson forceps or a retinal cryoprobe may be applied to the surface of the tumor capsule (or pseudocapsule) and with rotating and rocking motions can allow the mass to be pulled out (Figure 31.6). In rare instances, traction sutures may also be applied to the tumor for manipulation. The suturing of cystic tumor mass may be a mixed blessing. Oozing of luminal contents or blood from a cystic mass may reduce the size of the tumor and expedite the removal. On the other hand, once the cyst has collapsed, the surgeon loses the advantage of the force it applies to the adjacent tissues, and the mass does not easily push itself out of the orbit. This may be a particular disadvantage if there are strong tissue adhesions to the posterior surface of the mass. A right-angled vascular clamp may be a handy instrument to place behind the mass to break the adhesions.

If the purpose of the orbital exploration is not the removal of a tumor in toto but rather to perform an incisional biopsy or tumor debulking procedure, more bleeding should be expected in the field following the

initial cut of the tumor. Therefore, the surgeon should make every effort to expose a large area of the tumor for the initial biopsy and excise as much tissue as possible during the first pass. This may be accomplished as a wedge biopsy with the use of a long scalpel blade and an Adson forceps. At times, a disposable skin punch or a small-diameter corneal trephine attached to the tip of a straight hemostat can be used to core out a tumor biopsy sample to be cut with an angled knife. For the posteriorly located or apical lesions, where the exposure is difficult, a core biopsy can be done with a Jamshidi bone marrow needle or with the fine-needle aspiration technique (see Chapter 12). If the lesion to be sampled is very small and confined to the apex, ultrasound guidance or a stereotactic image guidance system may be used (see Chapter 32).

At the end of the exploration, one must ensure that the bleeding is adequately controlled. After this, the periorbita is carefully approximated and closed by means of interrupted 5-0 Vicryl sutures and then the bone muscle flap is moved to its original position to be reinserted and secured with 2-0 nylon sutures using the preplaced drilled holes. The periosteum can then be closed over the bone with several interrupted 5-0 Vicryl sutures, and the same type of suturing can be applied to the overlying temporalis fascia if it was detached from the bone; if the bone–muscle flap has been left intact, this is not necessary. A drain should be inserted during the closure.

The skin wound is closed with 6-0 nylon sutures on a bolster in a continuous or subcuticular fashion. The placement of the suture with a bolster expedites

the removal. After skin closure, the traction sutures and the anchoring suture of the lateral rectus muscle are removed and the conjunctiva is closed with bipolar cautery or with one or two absorbable sutures. Following this, the conjunctival sac is irrigated with a small amount of buffered saline solution, and Maxitrol ophthalmic ointment is instilled; the ointment is also applied to the wound and to the drain site. During the surgery, antibiotics and corticosteroids are given intravenously. It is important that the extubation of the patient at the end of surgery be done gently, without bucking of the patient.

Inferior Wall (Floor) and Inferior Orbitotomy

The triangular orbital floor primarily consists of the maxillary bone (MB) and the greater wing of the sphenoid bone; between these two bones is the inferior orbital fissure. The IOF connects the orbit with the pterygopalatine fossa. The inferior orbital nerve and the veins that drain the inferior orbit transmit through the IOF. The inferior orbital nerve enters a bony groove of the floor approximately 25-mm posterior to the rim and travels forward to enter the fascial tissues through the inferior orbital foramen. The dissection for extraperiosteal orbitotomy should, therefore, be done posterior to the exit of this nerve. However, it should be kept in mind that the nerve may lie rather superficially under the bone, and one should be aware of its actual location. Damage to the nerve would lead to numbness in the lower lid and inferior periorbital region, cheek and upper lip. Rarely are tumors found in the inferior orbit. However, lymphoid lesions, peripheral nerve tumors, and metastatic tumors are occasionally encountered in this area.

For inferior orbitotomy there are two basic approaches. If the pathology is located anterior to the septum, a subciliary incision allows the surgeon to gain easy access to the lesion. The same incision can also be used to access the inferior orbital space through the septum. The direct cutaneous incision approximately 25 mm inferior to the lid margin would allow one to get into the orbit by avoiding the lower lid retractors and the inferior oblique muscle and does not interfere with the lower lid function postoperatively. Since, however, the scar of this incision may be unsightly, in cutting one should follow the relaxed skin tensions lines.

From the cosmetic standpoint, the preferred approach is transconjunctival through the inferior fornix; this approach also offers access to the midorbit.31,32 This is best accomplished by doing a canthotomy incision by scalpel blade over the inferior crus of the lateral canthal tendon.33 Once the lateral canthal tendon is cut, the lower lid is stabilized with a forceps and pulled down, exposing the conjunctiva

of the lower fornix. The lower fornix conjunctiva may be incised with curved Stevens scissors or by finetipped (Colorado tip) unipolar cautery. During this incision, by passing a traction suture under the inferior rectus muscle to rotate the eye upward and resting the scissors on the bone of the inferior orbital rim, one can easily become oriented to the anatomy. On the other hand, the advantage of the cautery incision is that the underlying lower lid retractors can also be cut with a minimal amount of bleeding. When the lower lid retractors have been cut at their point of attachment to Lockwood’s ligament, one enters the inferior space anterior to the inferior oblique muscle. An incision along this line causes minimum trauma to the lower lid retractors. The advantages of this “swinging eyelid” or “hinged eyelid” technique include good exposure of the infraorbital space, quick closure, and minimal postoperative complications and scarring (Figure 31.13). The inferior fornix incision should be closed with a few interrupted 6-0 Vicryl sutures, which can also be used for the reattachment of the inferior crus of the lateral canthal tendon to its disinsertion point. Conjunctiva can be closed with a 6-0 or 7-0 chromic running suture. If the infraorbital orbitotomy extends toward the medial aspect of the orbit, one should be aware of the anatomy of the lower canaliculus and lacrimal sac. During surgery, the canaliculus may be probed and isolated; care should be taken at the closure to avoid symblepheron formation of the conjunctiva, which may lead to epiphora and ectropion of the eyelid after surgery.

MEDIAL WALL AND MEDIAL ORBITOTOMY

Most of the medial wall consists of the thin lamina papyracea separating the orbit from the neighboring ethmoid sinus. Lamina papyracea is primarily made of ethmoidal bone (EB) with neighboring frontal bone (FB) superiorly, lacrimal bone (LB) anteriorly, and maxillary (MB) bone inferiorly. Anterior and posterior ethmoidal neurovascular bundles usually lie at the suture line between the ethmoid and frontal bones (Figure 31.8). This is a critical landmark because it helps identify the roof of the ethmoid sinus, and the disruption of the bone above this level may damage the dura of the frontal lobe (Figure 9.2). A useful mnemonic to remember the approximate positions of the ethmoidal neurovascular bundles relative to anterior lacrimal crest is “24-12-6.” The numbers indicate that the distance from the lacrimal crest to the anterior ethmoid foramen is 24 mm; there is 12 mm from the anterior to the posterior ethmoid foramen; and the measurement from the posterior ethmoid foramen to the anterior osteum of the optic canal is 6 mm. If one is well oriented with the anatomy, the anterior and posterior

ethmoidal arteries can easily be identified and tied, clipped, or cauterized to maintain a bloodless field during medial wall exploration.

Lacrimal drainage system anatomy should also be kept in mind during medial orbitotomy. The lacrimal sac and the superior portion of the nasolacrimal duct lie within a shallow bony fossa, bordered anteriorly by the anterior lacrimal crest, which is made of an ascending extension of the maxillary bone (Figures 31.7 and 31.8). The lacrimal sac fossa is limited posteriorly by the lacrimal crest of the lacrimal bone. The anterior and posterior limbs of the medial canthal tendon insert onto the anterior and posterior lacrimal crests, respectively.

Another important landmark in medial orbital exploration is the sphenoethmoid junction, where the ethmoidal bone meets the sphenoid bone posteriorly. The location of this junction is variable but usually is at the level of the anterior osteum of the optic canal. In this posterior location, the exposure is practically nil, even in bloodless, well-illuminated fields. One very useful technique for orienting the surgeon to the anatomy is image-guided stereotactic surgery, in which the identifying probe is placed on apical structures that can be seen on the monitor with the help of the image guidance system (see Chapter 32). Although this procedure is primarily useful to identify the posterior ethmoidal cells and to perform decompression surgery, it can also be helpful to identify apical tumors. Blind dissection is likely to damage the vital structures of the orbit going through the optic

canal and the superior orbital fissure. At best, the lesions in this area, such as meningiomas and other posteriorly located nerve tumors, can be biopsied with the help of the image guidance system,34 ultrasonography, or CT during the biopsy procedure.

Medial orbitotomy can be done through a cutaneous approach or a transconjunctival (transcaruncular) approach. The skin approach is best accomplished by direct or modified Lynch incision, which is a slightly curved cut, starting from mid-eyebrow and extending downward and medially toward the lateral surface of the nose (Figure 31.1). It is best to keep the skin cut shallow and to do the subcutaneous dissection carefully, since the superomedial orbit contains several important structures. The beginning of the Lynch incision is usually initiated at the level of the superior orbital rim or a few millimeters above it. In this area, one should be careful not to damage the nerves of the superior orbital bundle (sof in Figure 31.8). As the incision makes a bend inferiorly, it overlies the trochlea, which is a small cartilaginous structure located in a bony fossa in the superomedial orbit 5 to 7 mm posterior to the rim.35 If a mass lesion within the medial fat pad does not directly involve the trochlea, the blunt dissection should be done posterior to this structure to avoid any damage. In most cases, the superior oblique muscle tendon can easily be retracted away from the exploration field. However, if the removal of the trochlea is mandatory, it should be done with care. The trochlea is a U-shaped ring with its opening firmly attached toward the medial

wall periosteum (Figure 31.14). The superior oblique muscle tendon passes between the periosteum and the cartilaginous flange of the trochlea and turns posteriorly to form its reflected arm.36 When the trochlea is removed from the underlying bone, it is advisable to leave a stump of periosteum attached to the trochlea, which is marked with a silk suture for accuracy during reattachment. The reattachment suturing should be done from periosteum to periosteum. No suture should be passed into the medial aspect of the trochlea, since this can easily scar the superior oblique

FIGURE 31.14. Diagram of the anatomy of the trochlea combined with the histologic section going through a vertical plane. T, trochlea; SOM, superior oblique muscle; OP, orbital periosteum. (Courtesy of Dr. Joel Sacks of New Orleans, Louisiana.)

tendon and may lead to a postoperative superior oblique restriction (acquired Brown’s syndrome).

As the Lynch incision curves down to follow the inferior orbital rim, it may overlie the angular artery and vein and approach the upper canaliculus and the underlying medial canthal tendon (MCT). If the lower limb of the incision extends over the medial canthal area, the surgeon should be aware of the level of the tendon (MCT) and the underlying lacrimal sac.37,38 The anterior limb of the MCT, which can be palpated through the skin, may be visualized after a shallow skin incision. The anterior limb under which the lacrimal sac lies originates from the anterior lacrimal crest (Figure 31.7). The MCT cannot be retracted easily for dissection. If wide exposure is needed in this area (e.g., lacrimal sac tumors), the MCT should be disinserted from the periosteum and reattached in its proper position after the exploration.

One may choose to probe the canaliculi during the dissection in this area; it is also advisable to irrigate the lacrimal drainage system following the medial orbital exploration to ensure its patency. If the LDS is disrupted secondary to tumor compression, every possible effort should be made to repair the damage; on the other hand, if the system is infiltrated with a malignancy, it must be sacrificed during dissection. The anatomy of the proximal LDS may be maintained after the removal of benign, well-encapsulated lesions. If this cannot be managed, dacryocystorhinostomy (DCR) may be performed during the same session and silicone stents passed into the nose. Same-session DCR is advisable only if the tumor is benign and the surgeon does not anticipate any further surgery. If, however, postoperative external beam radiation therapy (EBRT) is anticipated, silicone intubation may prove advantageous to minimize radiation scarring of the drainage system. If the canaliculi are intact but the sac or the nasolacrimal duct is damaged beyond repair, the same approach is advised. However, if the canaliculi cannot be salvaged because of extensive tissue loss, it is best to reconstruct the eyelid and the canthus as well as possible and to leave the lacrimal bypass surgery for a future session after the scarring of the area is stabilized.38

The medial orbit can also be explored through a transcaruncular incision.39–42 During transcaruncular medial orbitotomy, a crescent-shaped incision is made through the posterior limb of the medial canthal tendon to which the deep head of pretarsal orbicularis muscle attaches to reach the underlying bone.39 About 10 to 15 mm posterior to the caruncle, the deep head of the pretarsal orbicularis muscle (Horner’s muscle) becomes visible. When this muscle is cut, the orbital fat presents itself; upon retracting the fat with a thin ribbon retractor, one can easily identify the posterior lacrimal crest. At this point the periosteum may be cut and elevated and the dissection may be carried pos-

teriorly below the periosteum with periosteal elevators and malleable retractors. On the other hand, one may choose to stay within the periorbita to explore retrobulbar tumors located in midorbit. This approach is also a direct route to the optic nerve and is preferred by many surgeons for optic nerve sheath decompression. The optic nerve can be reached through the transcaruncular approach without disinserting the medial rectus muscle. However, the exposure, which may be good for the removal of small tumors and for biopsy purposes, does not offer the best surgical field to operate on the optic nerve sheath. For this purpose it is best to do a 120° peritomy a few millimeters anterior to the insertion of the medial rectus muscle and to isolate the medial rectus muscle with a double-armed 6-0 Vicryl suture. Then a 5-0 Merseline suture on a spatula needle is passed through the stump of the tendon of the medial rectus muscle in a running fashion. Both ends of the Merseline suture are threaded with silicone tubing to protect the cornea while retracting the globe laterally (Figure 31.14). The next maneuver is to push the globe down gently while retracting the silicon tubing laterally as the assistant retracts the medial rectus complex medially with a malleable retractor. This affords a quick and easy access to the midconal space; however, visibility is obscured by retrobulbar fat. When the retrobulbar fat has been bluntly dissected with cotton tip applicators, the posterior ciliary arteries and the optic nerve come into view. If the orbitotomy is being performed for optic nerve sheath fenestration procedure, a cotton tip applicator holder may be useful to push the fat posteriorly on both sides of the optic nerve and isolate the dura (Figure 31.14). The cotton tip applicator holder is particularly helpful if one is doing the procedure alone because it will stand up on its own while the surgeon is handling other instruments. When the dura is exposed, it is picked up with microsurgical forceps (the author prefers the Belushi forceps, a microforceps for middle ear surgery) toward the edge of the optic nerve and a vertical incision is made into the dura with a no. 75 blade. At the time of this cut, it is common to see cerebrospinal fluid gushing through the incision. Next, a cut parallel to the first one can be made and a rectangular window removed with microscissors. Or a small muscle hook can be inserted through the first incision, whereupon the subarachnoid trabeculae are broken away from the overlying nerve sheath, and a small amount of Healon® is injected to balloon the dura. When enough room has been created, the glaucoma punch (Katena®) is inserted underneath the dura and a round hole is punched out in the optic nerve sheath. This may be difficult to do in deep orbits because of the limited length of the punch instrument. Following the establishment of the opening, the medial rectus muscle is reinserted and the conjunctival peritomy is closed.43

The most commonly encountered space-occupying lesions in the medial orbit are mucoceles, bone and peripheral nerve tumors, and hemangiopericytomas. Small mucoceles may be removed in toto, but in most instances these lesions extend into the sinuses (Figure 31.15). In these cases, the bony shell can be removed partially and the mucosa of the cyst is stripped off completely or as much as possible. If some of the mucosal lining cannot be removed, it is best to cauterize the leftover mucosa and establish an opening between the mucocele and the adjacent sinuses.

Combined Medial–Lateral Orbitotomy

If the lesion is medially located but close to the apex, exposure is not possible laterally and may also be limited through a medial caruncular approach. In this situation, a combination of medial and lateral orbitotomies may be performed. This approach is also useful when the tumor to be removed is too large for the exposed surgical field. First, lateral orbitotomy is done and the medial rectus muscle is disinserted so that the globe can be retracted laterally, allowing more room for tumor dissection in the medial orbit. With the medial rectus muscle disinserted, the globe can be displaced temporally, offering a better exposure of the medial apex area (Figure 31.16).44 This combination approach is useful for small, apical tumors. Larger lesions, particularly the infiltrative lesions, however, cause considerable anatomic distortion, and therefore, a transfrontal craniotomy may be needed to provide wide exposure of the posterior orbit.45

Superior Wall (Roof) and Superior Orbitotomy

Superiorly the rim is most protuberant. The supraorbital notch is located at the medial third of the rim. This notch provides a safe landmark to identify the supraorbital neurovascular bundle, which harbors the superior orbital branch of the frontal nerve and blood vessels. The trunks of the supraorbital and supratrochlear nerves are important sensory branches of the ophthalmic nerve (CN V-I). The trauma to the supraorbital nerve should be minimized during superior orbitotomy and transcoronal orbital approach. Often one can chisel out a small rectangular bony piece of the superior rim around the nerve, which allows the nerve to be moved away from the surgical field, but if there is an infiltrating lesion this may not be possible. During a subperiosteal approach, one should look for the trunk exiting the superior orbital foramen because variations may happen. The posterior dissection of the periosteum should be made cautiously because, in some cases, the supraorbital nerve leaves the bone posterior to its usual location. The orbital roof primarily consists of the frontal bone and the lesser wing of the sphenoid bone. The anterior cranial fossa and the

frontal sinus are located above the orbital roof, and, therefore, one should be familiar with the anterior margin of the cranial fossa to limit the superior orbital osteotomy. Since both the anterior extent of the cranial fossa and the aeration of the frontal sinus vary from case to case, it is best to determine these relationships to the superior orbit prior to the exploration, by a thorough inspection of the CT scan. Recurrent benign and malignant tumors (e.g., lacrimal gland lesions) may easily violate the frontal sinus and cranial bone, distorting the anatomy and extending into the sinus or cranial fossa (Figure 31.17).

One should keep in mind that even the small tumors developing in this region such as dermoids (particularly leaking dermoids, which cause secondary inflammation), cholesteatomas, or mucoceles may easily disturb the anatomy and function of the trochlear apparatus. Therefore, this region should be dissected carefully, particularly in the presence of pathology. The superior ophthalmic vein originates within the same superior medial fat pad and runs posteriorly, leaving the orbit through the superior orbital fissure above the annulus of Zinn.

Orbital Apex

In adults, the optic canal is approximately 10 mm long and varies from 5 to 6 mm in diameter at its orbital osteum.46 It is located at the posterior-most extension of the orbital apex between the lateral, medial, and superior walls of the orbit within the lesser wing of the sphenoid bone. It transmits optic nerve, ophthalmic artery, and sympathetic fibers from the orbital cavity to cavernous sinus.47 The optic nerve, surrounded by the meninges, enters the canal on the medial aspect of the posterior orbit. In the adult, the nerve measures approximately 25 mm from the posterior sclera to the entry of the optic canal; however, the posterior sclera is only about 18 mm anterior to the canal. This 7 mm infero-temporal slack on the nerve allows the globe to move to all gazes freely without applying tension on the nerve. Gradual loss of visual acuity and visual field are generally due to optic nerve compression secondary to apical tumors. Nerve appearance and function can be monitored with color vision testing, afferent pupillary light reflex, visual perimetery, visual evoke response (VER), or ophthalmoscopy, depending on the clinical setting (See Chapter 7).

FIGURE 31.16. Combined lateral and medial orbitotomy procedure to remove a posteriorly located cavernous hemangioma. (A,B) A lateral orbitotomy is performed through a lid crease incision shown in Figure 31.11A. Later an inferior medial orbitotomy is performed with this insertion of the medial rectus muscle, and the globe is retracted laterally as much as possible. (C,D) This maneuver allows the inferior medial orbit to be explored with ease, and the tumor is removed within its capsule with the help of a cryoprobe.

The annulus of Zinn is a fibrous ring that originates from the apical periosteum, surrounds the optic canal, and sprawls inferolaterally to surround some of the structures going through the superior orbital fissure, including the inferior and superior branches of

FIGURE 31.17. Removal of adenoid cystic carcinoma (AdCyCa) from the left lacrimal gland fossa. Inset: Axial CT scan shows the infiltration of the tumor into the bone (white arrow)

the oculomotor (third cranial) nerve, the nasociliary branch of the ophthalmic division of the trigeminal (fifth cranial) nerve, and the abducens (sixth cranial) nerve (Figure 31.9). The portion of the superior orbital fissure (SOF) outside the annulus transmits the trochlear (fourth cranial) nerve, the frontal and lacrimal branches of the ophthalmic division of the trigeminal nerve, and the ophthalmic veins.

The inferior orbital fissure is longer than the superior and sits between the lateral wall and the floor of the orbit. It transmits the maxillary division of the trigeminal nerve, which branches into the infraorbital nerve and forms the bundle together with branches of the maxillary artery and vein. The bundle exits the orbit through the infraorbital foramen below the inferior rim.

Although there are general guidelines for orbital exploration in tumor surgery, no absolute rules can be formulated, particularly when there is preoperative uncertainty about the extent and the nature of the tumor. Therefore, it is very beneficial to obtain as much preoperative data as possible before beginning exploration of the orbit.

Enucleation

Enucleation, the removal of the globe by separating it from all its anterior and posterior soft tissue connections, is a relatively rare procedure in orbital tumor management. Most enucleations are done because of secondary orbital tumors originating from the globe and/or adnexae, such as malignancies of the eyelid and conjunctiva, choroidal melanoma, or retinoblastoma. In certain instances, conjunctival malignancies may extend into the globe without extensive extension into the orbit. When the sclera is infiltrated but the orbital extension is limited, the tumor may be controlled with enucleation and the excision of the localized orbital invasion without exenteration. In other instances, the globe may be left behind, but other tumor-infiltrated soft tissues are removed extensively.48

Orbital involvement by conjunctival melanoma is rare, but when this happens, orbital exenteration has been the traditional treatment of choice.49–51 However, if the orbital component of the tumor is small, limited excision of this lesion, combined with enucleation and/or orbital brachytherapy can be done.52 Similarly, in some cases of eyelid melanoma, localized surgical excision, with or without enucleation, may be considered over total exenteration.53

Enucleation plays a larger role in the management of squamous cell carcinoma of the conjunctiva (Figure 21.2).54,55 Since the growth of this tumor is slower than melanoma and it is more frequently seen in the bulbar conjunctiva, it invades the globe more often prior to its invasion of the orbit.56 Therefore, in many cases of global invasion, it is possible to control the tumor by means of enucleation and excising the involved portion of the conjunctiva before it extends through the orbital septum. In these cases, it is best to determine the tumor-negative margins of the conjunctiva under frozen section control, free the conjunctiva around the primary site of the tumor, and then do the enucleation. The surgical technique of these cases must be more deliberate and gentle than the ordinary enucleation because the tumor invading through the sclera may cause a weak area in the eye wall, leading to perforation of the globe during the procedure.

Another indication of enucleation may present in cases of extraocular extension of the uveal melanoma into the orbital soft tissues.57–59 The treatment of secondary orbital melanoma originating from the choroid depends on the size, location, and shape of the orbital components. If the orbital extension of the choroidal melanoma is solitary and limited to a delineated nodule outside the globe, management should consist of the enucleation of the eye with the nodule and secondary EBRT of the orbit.60–62 On the other hand, when the orbital extension is massive, the choice of

treatment is exenteration, with or without sparing the eyelids, depending on the location and the extent of the orbital component of melanoma.62,63

In some instances, retinoblastoma with limited transcleral and optic nerve invasion may also be treated with enucleation, combined with postoperative radiation. Extension of the retinoblastoma into the orbit is usually not nodular and therefore does not lend itself for easy surgical excision; however, this tumor is very sensitive to radiation and responds well to postoperative radiation treatment. Orbital radiation may lead to socket contraction and retarded growth of orbital soft tissues and bones; it may also increase the incidence of second primary malignant tumors, particularly in hereditary retinoblastoma (see Chapter 5). The invasion of the orbit in retinoblastoma is considered as a very serious risk factor for metastasis and is considered to be an indication for poor progno- sis.64–66 Orbital invasion is conventionally treated with a combination of radiation and chemotherapy, with or without enucleation. Advances in chemotherapy have increased the survival of these patients, but the prognosis is still very guarded.67,68

Other indications of enucleation in an orbital tumor patient include the development of a secondary, blind, painful eye, followed by neovascular or chronic angle closure glaucoma and chronic retinal detachment.69 In rare instances, an extensively proptotic, disfigured eye with chronic dryness, with or without secondary infections, may require enucleation for functional or cosmetic reasons.

Different surgical techniques of enucleation have been detailed in a number of excellent publica- tions.70–72 The purpose of this chapter is not to go through the enucleation technique step by step but to underline the pertinent points when enucleation is performed in a tumor-harboring orbit. In the case of conjunctival and eyelid tumors that extend into the globe secondarily, the excision around the primary focus of the tumor should be done prior to the enucleation, preferably under frozen section control. When the surgeon is satisfied that the margins of this excision are clear, the enucleation may follow. Care should be taken to not seed tumor cells to uninvolved areas of the orbit.

In posteriorly located tumors of the globe, secondarily involving the orbit, it is to the surgeon’s advantage to have the optimal visualization and/or palpation of the posterior surface of the globe before enucleation. The author’s preference is to do a large lateral canthotomy, push the globe anterior to the eyelids, and place the optic nerve on a stretch. From the lateral aspect of the orbit, the nerve, or at times a posterior choroidal melanoma extending into the orbit, can be seen or at least palpated. This may offer the advantage of removing the extrascleral tumor nodule with the globe. It is also better practice not to place trac-

tion sutures in the muscle stumps for enucleation in tumor-containing globes; in this way one avoids penetration of the sclera with underlying tumor (Figure 31.18). It is better to place a right-angle vascular clamp or a curved hemostat on the muscle stump for traction purposes. At the time of enucleation, if the tumor is identified and it is judged that the further excision would offer an advantage, then it is excised. On the other hand, if the orbital involvement is extensive, the case can be converted to exenteration, with or without postoperative EBRT.

Last, but not least, the tumor-containing globes should be injected with 0.5 mL of 10% formaldehyde in the operating room before they are submitted to the

FIGURE 31.18. (A) Gross and histopathologic specimens of an enucleated retinoblastoma-containing eye reveal the close proximity of the traction suture needle track (NT) to the underlying tumor (RB). (B,C) Traction is best provided by a curved hemostat applied to the lateral rectus muscle during the enucleation of an eye containing retinoblastoma.

FIGURE 31.19. Orbital implants made of hydroxyapatite (HA), methylmethacrylate (MM), and porous polyethylene (PP).

pathology laboratory. This measure serves to maintain the shape of the globe for pathology processing and, therefore, better orients the pathologist to the tumor. Furthermore, it is essential that the specimen be anatomically oriented and marked with sutures and sampled accordingly; this may offer invaluable information for the future management in tumor cases, particularly if the tumor recurs in the orbit.

When the enucleation procedure is performed for a nonneoplastic disorder, a variety of orbital implants may be placed into the socket at the time of surgery depending on the decision of the surgeon and the needs of the patient.73–75 In general, implants function to replace the volume lost by the enucleated eye, to support the ocular prosthesis for good motility, and to maintain cosmetic symmetry with the normal eye. Basically, there are two major groups of orbital implants: integrated and nonintegrated. The advantages and disadvantages and surgical techniques of implantation of orbital spheres have been covered in numerous publications in recent years.69,76,77

Our purpose here is to look at the specific needs of a tumor-containing eye/orbit after enucleation. In many instances, any implant can be placed into the orbit if one is confident of the total removal of the tumor, a difficult judgment in many instances. Therefore, it is logical that a rather simple implant made of silicone, acrylic, or polymethylmethacrylate (PMMA) be placed in the orbit; this would provide good volume replacement and in most instances acceptable motility. In case of a recurrence, these implants can be removed more easily than the integrated ones. We have studied the appropriateness of different types of orbital implant from the standpoint of radiation absorption properties and could not document a significant difference between PMMA, hydroxyapatite (HA), and porus polyethylene (PP) implants (Figure 31.19).78 Arora and coworkers are in agreement, indicating that HA implants have no significant influence on the attenuation or scattering properties of the photon beam that may need to be used in some patients following enucleation of tumor-containing eyes.79