Orbital Decompression

Orbital decompression is a surgical procedure used to improve the volume-to-space discrepancy that occurs primarily in patients with 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 is created during the surgery (Fig 7-9). This expansion relieves pressure on the optic nerve and its blood supply; it also reduces proptosis and orbital congestion.

Historically, decompression included removal of the medial orbital wall and much of the orbital floor, including the maxillo-ethmoidal strut, allowing the orbital tissues to expand into the ethmoid and maxillary sinuses. The approach was made through a maxillary vestibular or transcutaneous incision. However, globe ptosis and upper eyelid retraction could be exacerbated postoperatively, especially in patients with large, restricted inferior rectus muscles. This type of decompression could also disrupt globe excursion due to prolapse of the muscles into the sinus space and displacement of the orbital contents.

The approach currently used by many orbital surgeons combines 1 or more discrete incisions that allow access to the lateral, inferior, and/or medial walls. Entry to the lateral and inferior orbit is provided by an upper eyelid crease incision, an extended lateral canthotomy incision, or an inferior transconjunctival incision combined with a lateral canthotomy/inferior cantholysis. Decompression of the lateral wall can be achieved by using rongeurs and/or a drill to remove bone along the sphenoid wing (Fig 7-10). A retrocaruncular incision allows an excellent approach to the medial orbital wall; it can be used in conjunction with a transconjunctival incision for further access. Alternatively, a transnasal endoscopic approach to the medial orbit via the ethmoid sinus may be used to access the medial wall.

Figure 7-9 Bony anatomy of the right orbit. 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.)

Figure 7-10 Orbital decompression of the lateral wall. A drill is introduced through a left lateral upper eyelid crease incision to remove bone along the greater sphenoid wing during orbital decompression in a patient with thyroid eye disease.

(Courtesy of M. Reza Vagefi, MD.)

Figure 7-11 Orbital decompression for thyroid eye disease. Before (A) and after (B) bilateral, “balanced” orbital decompression of the medial and lateral orbital walls.

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

Some surgeons choose to decompress the orbit in a “balanced” manner by removing bone from the opposing walls, believing this will reduce the risk of worsened or new onset diplopia (Fig 7-11). For further decompression, occasionally some surgeons will remove the lateral orbital rim and/or reposition it anteriorly at the time of closure. Anterior displacement of the lateral canthus may also aid in the reduction of eyelid retraction.

Fat decompression with removal of retrobulbar fat further reduces proptosis and has also been shown to be beneficial in patients with compressive optic neuropathy. However, decompression through the orbital roof into the anterior cranial fossa is inadvisable.

• Rootman DB. Orbital decompression for thyroid eye disease. Surv Ophthalmol. 2018;63(1):86–104.

Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.