Nd:YAG laser goniopuncture is an essential component of non-penetrating glaucoma surgery (NPGS). NPGS includes deep sclerectomy, canaloplasty, and viscocanalostomy 1)2).
Intraocular pressure control after NPGS depends on aqueous filtration through the trabeculo-Descemet’s membrane (TDM). When this TDM thickens due to incomplete intraoperative dissection or postoperative fibrosis, aqueous outflow resistance increases and intraocular pressure rises.
Goniopuncture creates microperforations in the TDM, restoring direct aqueous outflow from the anterior chamber to the intrascleral space. This converts a failed non-penetrating filtration into a penetrating type, but because it is performed at a safe time after bleb formation, the risk of hypotony-related complications is significantly reduced.
Compared to trabeculectomy, NPGS has fewer hypotony-related complications but inferior long-term intraocular pressure reduction 1)2). Goniopuncture is an important adjunctive procedure that improves the success rate of NPGS.
Goniopuncture is a procedure specific to non-penetrating glaucoma surgery (NPGS) and is not indicated after trabeculectomy. In NPGS, the trabeculo-Descemet’s membrane remains intact, and laser perforation restores aqueous outflow. In trabeculectomy, a full-thickness perforation has already been created, so goniopuncture is not applicable.
Goniopuncture is considered when adequate intraocular pressure control cannot be achieved after NPGS.
Early postoperative indications (1 week to 2 months)
Cause: Increased aqueous outflow resistance due to incomplete TDM dissection during surgery.
Gonioscopic findings: The TDM window is thick, and there is no indentation into the intrascleral lake.
Caution: Within 4 weeks postoperatively, there is a risk of rapid decompression and anterior chamber loss, making it a relative contraindication.
Late postoperative indications (months to years later)
Cause: Progressive increase in aqueous outflow resistance due to fibrosis and pigmentation of the TDM.
Gonioscopic findings: Presence of blood, debris, or neovascularization in the intrascleral lake indicates impending fibrosis.
Caution: Should be performed before the intrascleral lake becomes completely fibrotic or collapsed.
In addition to topical anesthesia, instill 1% apraclonidine and pilocarpine. Miosis induced by pilocarpine reduces the risk of iris incarceration. If intraocular pressure is high, combine with a systemic carbonic anhydrase inhibitor.
Apply a gonioscopy contact lens and align the aiming beam of the Nd:YAG laser with the translucent TDM. Use the following parameters in free-running Q-switched mode.
The irradiation site should be anterior (toward the cornea) to minimize the risk of iris prolapse or peripheral anterior synechiae formation. To reduce the risk of iris incarceration after laser, argon laser iridoplasty may be performed near the TDM window.
Administer steroid eye drops (1% prednisolone acetate) three times daily for 3 days. Continue glaucoma medications until the follow-up visit. Re-examine after 1–3 weeks to check intraocular pressure and complications.
The most important complication is iris incarceration, occurring in up to 25% of cases. Risk is higher in the following situations:
Other complications include inflammation, hyphema, hypotony with choroidal detachment, and peripheral anterior synechiae. All are rare.
If iris incarceration occurs, attempt conservative management with miotics; if ineffective, consider laser or surgical synechialysis.
It has been reported that a single goniopuncture achieves at least a 20% reduction in intraocular pressure compared to before treatment for at least 2 years in about 50% of cases. It is positioned as an essential procedure for improving the success rate of NPGS and is the first-line laser treatment for intraocular pressure elevation after NPGS.
