Chapter 236

This chapter reviews the essential emergency medicine skills needed for ED eye examination, measurement of intraocular pressure (IOP), and use of the slit lamp. The diagnosis and treatment of common eye conditions and ocular emergencies that need ophthalmology consultation in the ED are discussed.

The orbit is a pyramid of bony walls that converge to an apex posteriorly. The orbit is bordered superiorly by the frontal sinus, medially by the ethmoid sinus, inferiorly by the maxillary sinus, and laterally by the zygomatic bone (Figure 236-1). The ethmoid bone (lamina papyracea) is paper thin and is the most likely sinus wall to break in blunt eye trauma or to be perforated due to sinusitis with subsequent spread of infection to the orbit. The orbital contents include the ocular muscles retroseptal fat and optic nerve, whereas the globe is considered a separate entity.

Figure 236-1.

Anterior view of bones of right orbit. (Reproduced with permission from Riordan-Eva P, Whitcher J: Vaughn & Asbury’s General Ophthalmology, 17th ed. New York, Lange Medical Books/McGraw Hill, 2008.)

The anterior limit of the orbital cavity is the orbital septum, which is a layer of fascia extending from the periosteum along the orbital rim to the levator aponeurosis of the upper eyelid and to the edge of the tarsal plate of the lower eyelid. The septum is generally impervious to bacteria, so serves to limit spread of infection from the facial skin into the orbit (Figure 236-2). All nerves and vessels of the eye enter through the apex of the orbit, which is also the site of origin for the extraocular muscles. The optic nerve is subject to compression from mass effect due to tumors, abscesses, or hematomas (Figure 236-3).

Figure 236-2.

Cross-section of the eyelids. (Reproduced with permission from Riordan-Eva P, Whitcher J: Vaughn & Asbury’s General Ophthalmology, 17th ed. New York, Lange Medical Books/McGraw Hill, 2008.)

Figure 236-3.

Anterior view of apex of right orbit. (Reproduced with permission from Riordan-Eva P, Whitcher J: Vaughn & Asbury’s General Ophthalmology, 17th ed. New York, Lange Medical Books/McGraw Hill, 2008.)

The arterial blood supply of the eye and orbit is the ophthalmic artery, the first major branch of the intracranial portion of the internal carotid artery, which enters the orbit beneath the optic nerve. The central retinal artery is the first intraorbital branch of the ophthalmic artery and courses through the optic nerve. The venous drainage of the eye and orbit is through the ophthalmic veins, which drain into the central retinal vein. The ophthalmic veins communicate directly to the cavernous sinus. This venous system has no valves that ...

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