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Primary Angle-Closure Glaucoma


In the past, variable and sometimes conflicting terminology has been used to describe different forms of angle-closure glaucoma. The problem arose from the fact that terminology was developed prior to the advent of indentation gonioscopy and laser iridotomy, when the mechanisms of angle-closure glaucoma were poorly understood.

In the era of surgical iridectomy, an attack of acute angle-closure glaucoma (AACG) could arise in an eye that had developed peripheral anterior synechiae (PAS) because of gradual angle closure prior to the development of the attack. Conversely, a prolonged acute attack or a series of subacute attacks could lead to progressive PAS formation. Patients undergoing surgical iridectomy were dilated routinely after surgery, and shallow anterior chambers were not uncommon. Patients undergoing surgical iridectomy for AACG who were dilated postoperatively and had shallow anterior chambers not infrequently formed PAS.
Prolonged apposition or repeated subacute attacks lead to gradual PAS formation. These usually begin in the superior angle, which is narrower than the inferior angle, as pinpoint synechiae, reaching to the midtrabecular meshwork and gradually expanding in width.

Primary angle-closure suspect (PACS) was defined as nonvisibility of the filtering trabecular meshwork for 180° or more in the absence of PAS with normal intraocular pressure (IOP). Primary angle closure (PAC) can be further classified as synechial or appositional. Primary (appositional) angle closure refers to an eye with raised IOP (>21 mm Hg) associated with obstructed filtering trabecular meshwork of more than 180° in the absence of PAS, disc damage, or field changes. On the other hand, primary (synechial) angle closure (PAC) refers to an eye in which portions of the anterior chamber angle are closed permanently by PAS with more than 180° of iridotrabecular contact with or without raised IOP. The term primary angle-closure glaucoma (PACG) is used to denote PAC eyes with glaucomatous optic nerve damage or visual field loss.

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