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César A. Sierra, MD · Frank A. Nesi, MD, FACS · Geoffrey J. Gladstone, MD, FAACS
Orbital procedures can be overwhelming, even to the experienced orbital surgeon. Fortunately, advances in neuroimaging modalities, microsurgical techniques, and instrumentation have revolutionized the way we look at orbital lesions. Computed tomography (CT) scans and magnetic resonance imaging (MRI) are crucial to accurately describe the location of a lesion and its relationship with adjacent orbital and cranial structures. Thorough preoperative evaluation and surgical planning followed by meticulous intraoperative techniques are fundamental to ensure the best outcome. Different approaches to the orbit are found in the literature. The surgical technique used will depend on the location of the lesion and the level of comfort of the surgeon. The most common approaches to the orbit, including orbital decompression surgery, will be discussed in this tutorial.
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Inferior Fornix Transconjunctival Approach
An inferior fornix transconjunctival
incision provides superb access and exposure to subconjunctival and
orbital masses located anterior to the equator of the globe, floor
fractures, and subperiosteal lesions. The concealed fornix incision
provides incomparable cosmetic results and requires less time than
transcutaneous procedures. Because the orbital septum is never violated,
complications of subcutaneous scarring and retraction are almost never
seen. The use of local anesthesia in appropriate cases is another
advantage of this relatively simple procedure.
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After sedation is induced, local anesthesia is injected into the inferior fornix. Exposure of the inferior fornix is achieved using a Desmarres retractor or a traction suture in the lower eyelid. Occasionally, a lateral canthotomy and inferior crus cantholysis are required to improve exposure in the presence of a tight eyelid. An incision extending from the lateral canthus to the area just below the inferior punctum is created 4 mm to 5 mm below the lower border of the tarsal plate to avoid injury to the septum and the canaliculus. A scalpel, thermal cautery, or unipolar cautery with a fine tip such as a Colorado needle can be used for the incision (Slide 1A). Palpating the inferior orbital rim with a cotton tip applicator while making the incision 2 mm anterior to it prevents the surgeon from inadvertently disinserting the inferior oblique muscle or entering into the orbit in an uncontrolled manner. Dissection is advanced through the lower lid retractors in a plane parallel to the septum (Slide 1B). Once the orbital rim is visualized, the surgeon has the option of exploring the orbit directly or gaining access to the subperiosteal space with the use of periosteal elevators. In the latter case, the periosteum can be incised posterior to the orbital rim to subsequently gain access to the orbital space if necessary.
Wound closure by secondary intention is the method of choice in fornix transconjunctival incisions. A 6-0 Vicryl suture in buried fashion may be used centrally for conjunctival closure if necessary when the tissues do not seem well opposed. Complications are rare and may include entropion, damage to the lower canaliculus during the incision, postoperative bleeding, and symblepharon. Secondary entropion due to disinsertion of the capsulopalpebral fascia is a theoretical concern but almost never observed. This approach can also be combined with a lateral or medial orbitotomy for posterior lesions and orbital decompressions.
Bulbar Transconjunctival Approach
The bulbar transconjunctival orbitotomy allows a
straightforward and simple way of reaching the anterior orbit in all
quadrants, as well as the intraconal space, for removal of tumors and
optic nerve sheath fenestration. Most of the anterior lesions can be
accessed with the use of local anesthetic and sedation, whereas deeper
surgery requires general anesthesia.
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A 180° conjunctival peritomy is created along the limbus. Relaxing incisions may be used to further extend the peritomy. The medial rectus muscle is isolated with a muscle hook after Tenon’s capsule is bluntly dissected. Then, the muscle is secured with a double-armed 6-0 Vicryl locked suture passed 2 mm behind its insertion followed by disinsertion proximal to the globe using scissors. Passing a locked 4-0 silk through the stump provides lateral traction if necessary. Malleable retractors are used to protect the globe and expose the lesion or the optic nerve. Extreme care should be taken when there is need for hemostasis in the posterior orbit. Iced water and absorbable collagen hemostatic sponges help attain hemostasis and decrease the need for aggressive use of cautery in the orbit. In the case of optic nerve sheath fenestration, a microsurgical blade is used until a leak of clear cerebrospinal fluid is observed. The medial rectus muscle is secured into its original insertion with the previously placed 6-0 Vicryl suture. The conjunctiva is closed with 7-0 Vicryl sutures or approximated with cautery.
Excellent illumination and magnification are vital for the success of an optic nerve sheath fenestration or excision of an intraconal lesion. Although this relatively simple approach provides access to the optic nerve, some surgeons still prefer a lateral orbitotomy for its wider exposure.
Combined Transcaruncular/Inferior Fornix Transconjunctival Approach
The transcaruncular incision provides
limited exposure of the medial orbit and apex. Nevertheless, it allows
excellent continuous exposure of the inferior and medial orbit when
combined with an inferior fornix transconjunctival approach. This
combination is especially useful in floor and medial wall fracture
repair as well as in orbital decompression.
After general anesthesia is induced, a peribulbar injection of
local anesthetic with epinephrine is administered. The inferior fornix
is exposed with a Desmarres retractor, and the fornix incision is
performed as previously described for the transconjunctival approach.
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The bulbar end of the conjunctiva may be sutured to the upper lid for corneal protection in long cases. A malleable retractor is used to protect the globe and improve the exposure. The periosteum is incised with a scalpel or Colorado needle tip and reflected using a Freer periosteal elevator. In blowout fractures, the periorbital and inferior rectus muscle are freed and the defect covered with an implant or graft.
In orbital decompression, the infraorbital nerve is a landmark for the orbital floor osteotomy. The neurovascular bundle is identified as a light gray line across the floor of the orbit and the thin overlying bone is meticulously unroofed using a small muscle hook. A hemostat or Stevens scissors can be used to carefully fracture the orbital floor into the maxillary sinus on both sides of the infraorbital nerve. The osteotomy is carefully enlarged with a Kerrison rongeur as much as possible leaving a bony strut between the floor and the medial wall to prevent diplopia (Slide 2).
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A maxillary antrotomy is created by "infracturing" a bony window into the sinus with a curve hemostat under the inferior turbinate and through the lateral nasal mucosa. A small diameter Foley catheter is introduced into the sinus and left in place overnight as a drain.
Next, attention is directed to the medial wall. An incision is created with Westcott scissors between the plica semilunaris and the caruncle (Slide 3A). Westcott scissors are introduced and spread apart after the posterior lacrimal crest is palpated. A small malleable retractor is inserted before removing the scissors to expose the lamina papyracea. The medial wall is fractured with a curved hemostat or suction tip and partially removed with Takahashi or Blakesley forceps (Slide 3B).
In an orbital decompression, bleeding can be initially addressed with absorbable collagen hemostatic sponges. Because the "orbital capacity" is expanded, minor bleeding is acceptable with strict postoperative monitoring if a drain is left overnight. Complications of the transcaruncular approach may include direct optic nerve damage, caruncular hypertrophy, diplopia secondary to damage to the inferior oblique muscle, and damage to the lacrimal system.
Inferior Transeptal Orbitotomy
The inferior orbitotomy involves a transcutaneous incision and is usually reserved for anterior lesions or floor fractures. An obvious limitation to this approach is the higher risk of scarring and retraction of the lower eyelid secondary to insult to the septum.
A subciliary incision 2 mm below the eyelash line is made with a scalpel medially below the punctum and extended laterally as needed. Using forceps to tent the skin edges, the orbicularis muscle and the septum are dissected with scissors or cautery. Desmarres and malleable retractors are useful for adequate exposure. The dissection is continued out until the periosteum is visualized. The periosteum can be incised using a scalpel or a Colorado needle tip and then reflected with Freer elevators to be able to reach the subperiosteal space.
The infraorbital neurovascular bundle can be identified as a grayish discoloration in the orbital floor. The overlying bone is extremely thin, thus, care should be taken to avoid any damage to the nerve or vessels. After the lesion is excised or repaired, the skin is closed using 6-0 absorbable or nonabsorbable sutures. The orbital septum should not be closed in any case. Complications include cosmetically unacceptable scarring, retraction, and lower lid ectropion, especially in the presence of significant lower lid laxity. Hypesthesia of the ipsilateral midface and tongue due to contusion of the infraorbital nerve usually resolves within 2 to 8 weeks after surgery.
Superior Transeptal Orbitotomy
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This approach is almost the mirror image of an inferior transeptal orbitotomy. Anterior lesions can be reached using this incision as well as subperiosteal abscesses or hemorrhage. The cosmetic result is generally well accepted because the incision is made in the upper eyelid crease or inferior brow area where it is well camouflaged (Slide 4).
A layered incision is required to identify and therefore avoid accidental damage to the next structure. Following the skin incision, the preseptal orbicularis muscle and the septum are dissected by tenting the edges of the wound. Pulling the septum anteriorly while exerting inferior traction on the inferior edge of the levator aponeurosis inferior will tent the septum away from the levator aponeurosis. Damage to the levator complex is prevented if the plane of dissection is always parallel to the plane of the levator aponeurosis. Once the septum is open, excision or biopsy of the lesion may proceed. Care should be taken to close skin without incorporating septum in the wound. We prefer 6-0 Prolene sutures for an imperceptible, seamless skin closure. Complications are usually preventable and may include upper lid retraction and ptosis.
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The lateral orbitotomy can be more intimidating and time consuming than other approaches. However, the lateral approach allows the best exposure to the lacrimal fossa and the posterior orbit including the intraconal space (Slide 5A). It may be combined with any of the anterior approaches to gain better access to the area of interest. The addition of the lateral orbitotomy to a medial approach enhances the exposure of the medial orbit and optic nerve by increasing lateral displacement of the globe.
After induction of general anesthesia, local bupivacaine with epinephrine is injected for hemostasis control and postoperative analgesia. A lazy S-shaped skin incision is marked along the orbital rim from the central inferior border of the eyebrow until the level of the lateral canthus where it extends laterally along the superior border of the zygomatic arch (Slide 5B). A limited conjunctival incision is made over the lateral rectus muscle. This is then isolated and marked with a suture or small Penrose tube for further identification and exposure of the intraconal space.
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The skin incision is advanced through orbicularis muscle and into periosteum. A Freer elevator is used to reflect the periosteum. Usually, the anterior portion of the temporalis muscle must be disinserted with cautery (Slide 5C).
The bone to be incised is marked with cautery at the frontozygomatic suture line area and just above the body of the zygoma. The globe and periorbital structures are always protected with a malleable retractor. Drill holes are made on either side of each line for later fixation (Slide 5D). The lateral wall is then incised using an oscillating saw and removed with a double action rongeur. Constant irrigation is essential to avoid thermal damage (Slide 5E and Slide 5F). Hemostasis with cautery and bone wax is a key element in this stage of the procedure. Excessive amounts of bone wax should be avoided when possible because it is known to retard bone healing and act as a nidus for infection. To prevent injury with the scalpel to the lateral rectus muscle, gentle traction on the Penrose tube should be applied at the same time that the periorbit is opened with a #11 Bard Parker blade.
After excision of the mass and careful hemostasis, the bone is fixed in its original position with either a 28-gauge surgical wire or a large size nonabsorbable suture (Slide 5G and Slede 5H). We prefer approximating the musculocutaneous flap using 5-0 Vicryl sutures in interrupted, inverted, subcuticular fashion. In most cases, no drain is required and skin can be closed with a running, subcuticular 6-0 Prolene suture for better cosmetic result.
Postoperative Care and Complications
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Any type of orbitotomy requires periodic visual acuity and pupillary reaction evaluation during the immediate postoperative period. Application of ice packs and elevation of the head of the bed are fundamental in reducing swelling and bleeding, especially during the first 72 hours. Valsalva maneuvers should be avoided and stool softeners may be prescribed. When required, a drain is kept for up to 48 hours. Medications include oral antibiotics and high-dose steroids with a quick taper. Antibiotic ointment is applied to the affected area three to four times a day and sutures may be removed in 1 week.
Increasing pain that is not relieved by mild analgesics is cause for concern after any of the orbital approaches. This suggests the development of an orbital hemorrhage and the patient should be evaluated immediately (Slide 6). An emergency exploration with evacuation of blood is crucial for preservation of vision. Intravenous acetazolamide, mannitol, and high-dose steroids are administered to decrease the intraocular tension caused by the posterior pressure and to limit the damage from compression and ischemia to the optic nerve. Blindness secondary to ischemic optic neuropathy follows if perfusion is not promptly reestablished.
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Loss of vision can also occur as an intraoperative complication, especially when working in the intraconal space. Care must be taken to avoid injury to the optic nerve and its vessels. It is essential to have excellent illumination and magnification as well as exposure when dealing with disorders of the optic nerve.
A superior orbitotomy or excision of eroding tumors can lead to cerebrospinal fluid leaks. Careful review of the CT scans with the neuroradiologist is crucial. The surgeon must identify the cases that benefit from a team approach that may include neurosurgeons, otolaryngologists, and craniofacial specialists.
Postoperative diplopia is a common complication. Double vision is usually transient and secondary to contusion or excessive manipulation of the extraocular muscles and their blood supply.
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Eyelid malposition may occur secondary to various mechanisms. Postoperative ptosis generally resolves as the swelling decreases. Excessive edema, hemorrhage, or direct trauma to the levator complex may result in aponeurotic ptosis, especially after superior and lateral approaches. Retraction of the lids may occur when a surgeon accidentally sutures the orbital septum. Ectropion and entropion are uncommon complications that develop secondary to excessive scarring of the anterior and posterior lamella, respectively.
Other uncommon complications include damage to the canaliculus during fornix incision, temporary hypesthesia, paralysis of cranial nerve VII, temporalis muscle atrophy due to aggressive hemostasis or dissection, and keratitis sicca secondary to lacrimal gland amputation.
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