The mechanism of IOP elevation in primary open-angle glaucoma (POAG) remains unclear.
The greatest resistance to aqueous humor outflow occurs in the juxtacanalicular tissue and the inner wall of Schlemm’s canal.
There is accumulation of extracellular matrix and a substance called plaque material in the juxtacanalicular tissue of the trabecular meshwork in POAG patients. This is thought to result in increased resistance to aqueous outflow through the meshwork.
Gonio scratch is a surgical procedure that improves aqueous humor outflow by rubbing off deposits on the trabecular meshwork with a Diamond Dusted Sweeper.
The Diamond Dusted Sweeper (DORC, Zuidland, Netherlands) is a diamond-dusted silicone-tipped manipulator. It was developed by Tano et al in 1997 to remove the epiretinal membrane during vitrectomy.
As the conjunctiva and trabecular meshwork are not incised, fewer complications and shorter operative times are expected with no postoperative bleeding, and minimal IOP spikes.
When combined with cataract surgery, gonio scratch is performed after the intraocular lens is inserted.
The Diamond Dusted Sweeper is used to scratch the trabecular meshwork to remove deposits in this region. This is performed over 120 degrees of the trabecular meshwork, and the region is scrubbed two to three times by the duster. [1]
The authors have reported the one-year findings of the Gonio Scratch Study. Forty-seven eyes of 47 patients underwent GS-Phaco surgery.
The median baseline IOP was 17 mm Hg. At 12 months postoperatively, there was a significant reduction in IOP to a median of 12 mm Hg ( P <0.01). The number of glaucoma medications also decreased significantly, from a median of 2 to 1 ( P <0.01). The surgical success rate at 12 months was 80.9%. The only complication observed was transient elevation of IOP in 2 (4.3%) eyes. No patient developed hyphema.
The authors concluded that GS-Phaco achieved sustained IOP reduction and a decrease in medication use at 12 months postoperatively in patients with POAG and cataracts. [2]
FOLLOW LINK FOR A PRIMER ON GONIOSCOPY:
https://touchophthalmology.com/glaucoma/journal-articles/gonioscopy-a-primer/
REFERENCES:
- Tokumo K, Okada N, Mochizuki T, Onoe H, Komatsu K, Okumichi H, Hirooka K, Mochizuki H, Yokoyama M, Kiuchi Y. The gonio scratch study: methodology of a multicenter clinical trial establishing a new minimally invasive glaucoma surgery. Nagoya J Med Sci. 2024 Feb;86(1):36-42.
- Tokumo K, Yokoyama M, Baba T, Okada N, Edo A, Komatsu K, Okumichi H, Mochizuki H, Miyoshi T, Kiuchi Y, Hirooka K. One-Year Outcomes of Gonio Scratch as a Minimally Invasive Glaucoma Surgery With Cataract Removal. J Glaucoma. 2025 Jun 1;34(6):468-475.
