Primary Angle-Closure Glaucoma
Primary angle-closure glaucoma (PACG) is a form of angle-closure disease in which the conditions of PAC are met, and there is also optic nerve damage and/or visual field loss consistent with glaucomatous optic neuropathy. Because of the insidious nature of this condition, vision loss may be the presenting symptom. Accordingly, this disease tends to be diagnosed in its later stages and is a major cause of blindness in Asia. The clinical course of PACG usually resembles that of open-angle glaucoma in its lack of initial symptoms, modest elevation of IOP, progressive glaucomatous optic nerve damage, and characteristic patterns of visual field loss. Over time, however, IOP can rise precipitously and become more difficult to control. The diagnosis of PACG is frequently overlooked, and this condition is commonly confused with POAG. As previously noted, gonioscopic examination of all glaucoma patients is important to establish an accurate diagnosis.
As with PAC, LPI is considered the standard of care. It has similar precautions related to eyes with extensive PAS in which a paradoxical rise in IOP can occur (see Treatment Controversies).
Medical treatment for PACG can include both aqueous suppressants and outflow drugs. Prostaglandin analogues are very effective for lowering IOP in angle-closure glaucoma, with efficacy similar to or exceeding that of β-blockers. The degree of IOP reduction does not seem to correlate with the amount of permanent angle closure. The efficacy of other outflow drugs, such as Rho kinase inhibitors, has yet to be established.
Cataract surgery alone is beneficial in reducing IOP and use of medications, and it compares favorably to cataract extraction combined with trabeculectomy. The recent EAGLE study showed that lens extraction can be an effective option in treating PACG. (See also Treatment Controversies.)
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Tham CC, Kwong YY, Leung DY, et al. Phacoemulsification versus combined phacotrabeculectomy in medically controlled chronic angle closure glaucoma with cataract. Ophthalmology. 2008;115(12):2167–2173.e2.
Tham CC, Kwong YY, Leung DY, et al. Phacoemulsification versus combined phacotrabeculectomy in medically uncontrolled chronic angle closure glaucoma with cataracts. Ophthalmology. 2009;116(4):725–731, 731.e1–3.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.