Types of Iridectomy

"Iridectomy" and "iridotomy" are often used loosely, but the distinction matters clinically: an iridotomy creates a hole without removing tissue (typically by laser), while an iridectomy surgically excises a piece of iris tissue. Both create an opening for aqueous flow, but their indications, technique, and current role differ.

Laser peripheral iridotomy (LPI) — current first-line

LPI (typically Nd:YAG) is now the default treatment for pupillary block and prophylaxis in narrow angles or angle-closure suspects. It is quick, outpatient, and has a much better safety profile than surgical iridectomy, which is why surgical iridectomy is rarely performed today except in specific circumstances (below).

• Indicated for: acute or chronic primary angle closure, angle-closure suspects with narrow angles at risk, prophylaxis of the fellow eye after an acute attack
• Increases angle width across all stages of angle closure, with a good overall safety profile
• Persistent angle closure despite a patent LPI is still reported in a meaningful minority of eyes (2-57% depending on disease stage) — LPI does not guarantee angle opening, especially in more advanced disease with synechial closure

An important current shift: clear lens extraction

Randomized trial evidence (including the EAGLE trial) now shows that in select patients — particularly acute primary angle closure and primary angle-closure glaucoma with elevated IOP — cataract/clear lens extraction can outperform LPI as an initial treatment, since removing the crystalline lens permanently deepens the anterior chamber and addresses the underlying anatomic crowding rather than just creating a pressure-equalizing bypass. This has shifted first-line thinking in some angle-closure scenarios away from "LPI for everyone" toward considering lens extraction earlier, especially when a visually significant cataract already coexists.

Surgical iridectomy — when it's still used

Surgical (incisional) peripheral iridectomy is now largely reserved for situations where LPI is not feasible or has failed:

• Corneal haze/edema precluding adequate laser view (e.g., during an acute attack with severe corneal edema)
• Combined with other intraocular surgery (e.g., performed intraoperatively during complex anterior segment procedures)
• Failed or inadequate LPI

Surgical iridectomy carries higher risk than laser (bleeding, inflammation, wound-related complications) — this is precisely why it has been largely superseded by LPI for routine prophylaxis and first-line treatment.

Argon laser peripheral iridoplasty (ALPI)

A distinct technique from iridotomy — ALPI contracts the peripheral iris stroma to mechanically pull the angle open, rather than creating a hole. It is a useful rescue option in acute primary angle closure when corneal edema precludes an immediate iridotomy, or when medical therapy alone fails to break the attack; often combined with argon laser pupilloplasty.

Key references: American Academy of Ophthalmology. Laser Peripheral Iridotomy in Primary Angle Closure (PPP report).  |  Day AC, et al. EAGLE trial: clear lens extraction for primary angle closure glaucoma.  |  He M, et al. LPI for the prevention of angle closure: RCT. Lancet. 2019;393(10181):1609-1618.