Tuesday, December 12, 2006

Section 9: Glaucoma Emergency: Acute angle closure glaucoma

Section 9-A: Introduction to acute angle closure glaucoma.

Acute angle closure glaucoma is a serious eye condition in which the drainage angle becomes obstructed such that aqueous humor cannot make its way out of the eye. The iris and cornea become pressed together and consequently, aqueous fluid cannot get to the trabecular meshwork and make its way out of the eye (figure 9-1). The result is a rapid elevation of intraocular pressure (IOP) that causes a constellation of symptoms including decreased vision, seeing halos around bright objects, pain, and nausea (Table 9-1). The intraocular pressure may become dangerously high and prompt treatment is necessary to prevent irreversible vision loss.

The most common form of angle closure glaucoma involves blockage of the pupil by the lens (pupillary block) and occurs in eyes that have narrow drainage angles. Pupillary block occurs when the lens comes in close contact with the iris around the pupil and prevents aqueous fluid from moving through the pupil. Aqueous fluid collects behind the iris and causes it to bow forward and close the drainage angle. The iris bows forward in the periphery and blocks aqueous fluid from reaching the trabecular meshwork and exiting the eye. This abnormal configuration of the iris prevents normal flow of aqueous fluid through the pupil to the trabecular meshwork and causes an acute rise in intraocular pressure (Figure 9-1).

Acute Angle-closure glaucoma

Figure 9-1. Acute angle closure glaucoma. A. In an eye with a normal configuration of the anterior segment, the angle between the iris and cornea is wide open (approximately 40˚). Aqueous fluid has free access to the trabecular meshwork and exits the eye unimpeded. B. In an eye with acute angle closure, the angle between the iris and the cornea is obstructed and closed. Aqueous fluid is trapped within the eye and causes the intraocular pressure to rise rapidly. (Same as Figure 5-1)

Table 9-1. Symptoms of acute angle closure glaucoma.

Decreased vision

Seeing “halos”


Nausea (sometimes)


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