Acute Angle Closure Glaucoma

Acute Angle Closure Glaucoma Aqueous humor is produced by the ciliary
body and flows out of the posterior chamber, along the lens and iris, through
the pupil, and into the anterior chamber where it is mostly drained through the
trabecular meshwork and into Schlemm’s Canal, located in the Iridocorneal
angle. Resistance arising within the channel between the iris and lens, can
disrupt the flow of aqueous humor, which builds up within the posterior chamber.
Obstruction can be due to a primary pupillary block or secondary to an
underlying disease. The resulting increase in pressure causes a distension
of the peripheral iris to the Iridocorneal angle, blocking out flow through
the trabecular meshwork. Now that the aqueous humor can no longer drain out of
Schlemm’s canal, the intraocular pressure rises and the typical clinical
presentation of acute glaucoma develops. An acute glaucoma attack is an absolute
emergency that requires immediate medical attention to prevent possible
blindness. It is vital that outflow of the aqueous humor is improved. This can
be accomplished by using miotic agents such as Pilocarpine, which can open up
the Iridocorneal angle by reducing pupil size. Additionally, production of the aqueous humor should be suppressed. This can be
done by inhibiting the ciliary body directly with carbonic anhydrase
inhibitors, such as acetazolamide. Osmotically active substances like
mannitol may also be useful in reducing the amount of aqueous humor. The goal of these measures is to quickly lower the intraocular pressure. To prevent
recurrences, surgery may be necessary after the pressure has been normalized.
The basic principle of the operation is to create a shunt between the anterior
and posterior chambers. This is mostly accomplished by peripheral iridectomy,
in which a piece of the iris tissue is removed in an open procedure. Alternatively, laser iridotomy can be
performed, which creates a small hole to allow aqueous humor to flow through. In addition, such procedures are often
prophylactically conducted on the unaffected eye or on a patient with very
flat anterior chambers.

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