Inferolateral marginal orbitectomy: a simple adjuvant technique for orbital decompression

Abstract

The number of patients with mild exophthalmos, without severe eye symptoms, who wish to undergo aesthetic orbital decompression, is increasing. Removal of the lateral and inferior orbital walls is a common procedure for mild to moderate exophthalmos. However, the limited space between the globe and the orbital wall is often troublesome for surgeons introducing surgical devices. As a result, the decompression tends to be insufficient in the posterior region of the orbit. We describe a simple adjuvant surgical technique to address this limitation. Through a laterally extended, transconjunctival approach, the inferior and lateral margins of the orbit are removed in a crescent shape before the actual decompression. This manoeuvre widens the working space and offers better visibility, enabling sufficient removal of the orbital walls. The technique presented facilitates the approach to the posterior regions of the orbit, enabling surgeons to more easily perform orbital decompression.

Introduction

Exophthalmos may result from a variety of conditions, including hyperthyroidism, chronic inflammation of the extraocular muscles, and congenital factors. Decompression of the orbit is performed as a corrective surgical treatment for the orbital protrusion. Orbital decompression provides a reduction in the compression caused by the orbital contents on the orbital wall by removing parts of the medial, inferior, and lateral walls, thus reducing intra-orbital pressure. However, removal of the orbital walls is often difficult, even for experienced surgeons. In particular, operating on the posterior regions of the orbit is challenging because of the limited space between the globe and the walls. The present report introduces a simple technique for an external approach to orbital decompression, especially for removing the lateral and inferior orbital walls.

Patients and methods

Typical surgical procedure

Under general anaesthesia, corneal protectors are applied. The lower eyelid is everted and then a transconjunctival incision line is marked, 2 mm beneath the inferior border of the tarsal plate. The incision line is extended to the eyelid skin, through the eyelid margin near the lateral canthus; the eyelid skin incision is extended laterally 1 cm into one of the crow’s feet lines. Two pairs of 6–0, non-absorbable traction sutures are placed superior and inferior to the marked line. After the conjunctiva is injected with an adequate amount of 1% lidocaine, containing epinephrine, meticulous incision of the conjunctiva and capsulopalpebral fascia is carried out with needle cautery.

Dissection proceeds between the suborbicularis oculi fascia and orbital septum to reach the orbital rim. Care must be taken not to incise the orbital septum to prevent herniation of the orbital fat and maintain good visualization of the region. For wide exposure, lateral cantholysis may also proceed, if necessary. Thereafter, the periosteum of the orbital rim is incised and detached from the zygoma, caudally, while the periorbita is detached from the orbit posteriorly; gentle dissection continues in the subperiorbital plane with a periosteal elevator. After the inferior and lateral aspects of the orbital margin are exposed, a crescent-shaped piece of bone, with a width of approximately 5–8 mm, length of 25–35 mm, and depth of 10–20 mm, is removed using an osteotome ( Fig. 1 ). Removal of the bone enables easy access to the posterior region of the orbit. An appropriate portion of the lateral and inferior walls may be removed, depending on the degree of orbital protrusion, using an ultrasound cutting instrument or drill. Several malleable retractors are used gently on the globe to maximize visibility. For cases of severe exophthalmos, the marginal orbitectomy can be extended both medially and superiorly to enable the removal of more bone from the orbital walls.

Fig. 1
Demonstration of the inferolateral marginal orbitectomy in a fresh cadaver. Left panel: a dotted line indicates the posterior line of the inferolateral marginal orbitectomy where the crescent-shaped bone piece will be removed. Right panel: removal of the bone piece facilitates access to the lateral and inferior walls.

The periosteum of the orbit is scored in a mesh-like fashion, facilitating expansion of the orbital contents into the temporal fossa and maxillary sinus. If necessary, orbital fat may be removed to allow for sufficient decompression. Thereafter, the orbicularis oculi muscle is secured to its original position, and the lateral canthus is secured to the inner side of the lateral orbital rim. After suction drains are inserted into the orbit, the conjunctiva and skin are closed with 7–0 absorbable and non-absorbable sutures, respectively. Postoperatively, compressive medication is applied for at least 48 h.

Clinical case 1

A 62-year-old man was treated for bilateral orbital protrusion that had been present for 20 years. The protrusion measured 23 mm using a Hertel exophthalmometer. A screening examination failed to reveal any evidence of hyperthyroidism or other disease; therefore, conservative therapy was not indicated. Thereafter, surgical treatment was conducted, for aesthetic reasons, to alleviate the eye protrusion. The patient’s written informed consent was obtained before the procedure.

After the bone piece was separated from the orbital margin ( Fig. 2 , left panel), parts of the lateral and inferior walls were removed, exposing the temporal muscle and maxillary sinus ( Fig. 2 , right panel). A sufficient amount of orbital fat was also carefully removed. In this case, the crescent-shaped bone piece was not repositioned within the orbit and was discarded. The orbital protrusion was reduced to 20 mm. No postoperative complications, including diplopia, developed. Although accurate perioperative visual acuity had not been recorded, the patient noticed a distinct improvement in visual acuity postoperatively. Pre- and postoperative computed tomography images are shown in Fig. 3 .

Fig. 2
Use of the inferolateral marginal orbitectomy in case 1. Left panel: a crescent-shaped bone piece was removed from the lateral and inferior aspects of the orbital margin. Right panel: partial removal of the lateral and inferior walls was performed.

Fig. 3
Computed tomography of the right orbit shows the preoperative condition and postoperative orbital decompression following inferolateral marginal orbitectomy in case 1. Left panel: preoperative condition. Right panel: postoperative condition.

Clinical case 2

A 53-year-old man with orbital protrusion, but without evidence of hyperthyroidism or other disease, was also treated. The protrusion measured using a Hertel exophthalmometer was 22 mm ( Fig. 4 , left panel). After the surgical procedure, the orbital protrusion was reduced to 20 mm ( Fig. 4 , right panel); there were no postoperative complications.

Fig. 4
Use of the inferolateral marginal orbitectomy in case 2. Left panel: preoperative condition. Right panel: postoperative condition.

Clinical case 3

A 22-year-old woman with hyperthyroidism was treated. The protrusion measured using a Hertel exophthalmometer was 18 mm ( Fig. 5 , left panel). After the surgical procedure, the orbital protrusion was reduced to 16 mm ( Fig. 5 , right panel).

Jan 19, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Inferolateral marginal orbitectomy: a simple adjuvant technique for orbital decompression
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