Luxation of the globe is a rare event whereby the eyelids slip behind the midcoronal plane of the eye in an extremely proptosed eyeball (Figure 163-1). The orbicularis oculi muscle then goes into spasm, which maintains the luxation of the globe. Extraocular eye movements become severely limited. The optic nerve and retinal vasculature are subjected to an abnormal amount of traction, resulting in possible damage to these structures or the retina.1 The end result is partial or full blindness in the affected eye if it is not reduced before irreversible ischemic changes occur.
The luxated globe. A. Superior view. B. Lateral view.
There are three major causes of globe luxation: spontaneous, voluntary, and traumatic. Spontaneous luxation tends to occur in individuals with shallow orbits.2 Structural abnormalities—such as laxity of the supporting muscles and fascia as well as anomalous extraocular muscles—can predispose to spontaneous luxation.2–4 Pathologic processes that cause proptosis can predispose to luxation. The literature documents cases of luxation associated with orbital tumors, Graves' disease, cerebral gummas, histiocytosis X, and craniofacial dysostosis.1,5,6 Voluntary luxation occurs in individuals who learn to cause globe propulsion by using a digit or use of their extraocular muscles. Some patients use a Valsalva maneuver to luxate their globe(s) voluntarily. Traumatic luxation results from trauma to the globe or the surrounding bony orbit. It can occur from motor vehicle accidents or even relatively minor trauma to the face.7,8 Traumatic luxation can also occur from intentional eye gouging or even during the forceps-assisted delivery of a neonate.9,10
The normal anatomic relationship of the globe to the surrounding structures is seen in Figure 163-2. The midcoronal plane of the eye is a transverse section through the eye in the coronal plane. It is through the widest portion of the eye and divides the eye into anterior and posterior halves. When the eyelids get behind the midcoronal plane, the orbicularis oculi muscle is pulled taut and begins to go into spasm. This spasm prevents spontaneous reduction of the globe.
Anatomy of the eye and orbit.
Globe reduction is indicated to relieve traction on the optic nerve and retinal vessels. The patient's visual acuity has the potential of being compromised without prompt reduction. Sustained globe luxation is physically and psychologically uncomfortable for the patient, may result in permanent loss of vision, and is difficult to reduce without general anesthesia.
Obvious rupture of the globe and extensive orbital fractures that require immediate surgical intervention are relative contraindications to globe reduction. Edema and retrobulbar hemorrhage can make reduction outside the Operating Room impossible.1,6
- Topical ocular anesthetic agent (e.g., 0.5% proparacaine or tetracaine)...