Indications and Contraindications
LPI is performed when iridotrabecular contact is thought to be caused by relative pupillary block. Patients with acute primary angle closure (APAC), primary angle closure (PAC), and primary angle-closure glaucoma (PACG) all benefit from iridotomy. In addition, it is often performed in primary angle-closure suspects (PACS), although it is unclear whether LPI is beneficial for these patients (see later section on Efficacy for further discussion). Eyes with secondary angle closure due to pupillary block also benefit from iridotomy. Multiple and/or larger iridotomies may be indicated for patients with significant posterior synechiae.
Figure 13-3 Illustration of eye with angle closure (top). Laser iridotomy or surgical iridectomy breaks the pupillary block and results in opening of the entire peripheral angle (bottom) if no permanent peripheral anterior synechiae are present.
(Reproduced and modified with permission from Kolker AE, Hetherington J, eds. Becker-Shaffer’s Diagnosis and Therapy of the Glaucomas. 5th ed. Mosby; 1983.)
In patients with a very shallow or flat peripheral anterior chamber, LPI can cause damage to the corneal endothelium. In patients who have angle closure without pupillary block (eg, neovascular glaucoma, ICE syndrome), iridotomy is ineffective. Eyes that have already developed 360° of synechial angle closure (due to chronic iridotrabecular contact) do not benefit from iridotomy.
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.