Technique of goniocurettage: a potential treatment for advanced chronic open angle glaucoma

Abstract

Aim: To introduce a new concept of anterior chamber angle microsurgery, designed to scrape pathologically altered trabecular meshwork from the scleral sulcus as a potential treatment in primary open angle glaucoma.

Methods: Gonioscopically controlled ab interno abrasion of the trabecular meshwork was performed on six human eye banking eyes for morphological analysis. Thereafter, four eyes suffering from terminal glaucomatous optic nerve atrophy as a result of medically uncontrolled intraocular pressure were also treated by 'goniocurettage'. The newly designed instrument resembles a modified cyclodialysis spatula with a bowl-shaped tip, 300 microns in diameter, and with its edges sharpened. The treatment zone comprised 4-5 clock hours of the chamber angle circumference.

Results: Microscopic examination of the treatment zone revealed that in addition to a complete disruption of the trabecular meshwork and internal wall of Schlemm's canal goniocurettage also caused damage to intracanalicular septa. A splitting along the posterior wall of Schlemm's canal was also noted in one specimen. The clinical data of goniocurettage also showed some promising results. Mean pretreatment IOP averaged 40.7 (SD 8.8) mm Hg (range 32-51 mm Hg) and was significantly (p < 0.04) reduced to 18.0 (4.2) mm Hg (12-22 mm Hg) after 6 months, representing an absolute decrease in IOP of 22.7 mm Hg and a mean decrease in IOP of 56%. Clinically significant hyphaema occurred in one eye, caused by introgenic trauma to a prominent chamber angle vessel. In three eyes a minor reflux of blood occurred at the treatment site. However, no hypotony, choroidal effusion, flattened anterior chamber, or cyclodialysis were observed in these patients.

Conclusion: Morphological analysis of treated postmortem eyes confirmed that goniocurettage completely removed the trabecular meshwork and opened Schlemm's canal, ensuring direct access into the anterior chamber. In a small number of patients over a limited period of time this new surgical procedure resulted in a clinically significant pressure reduction. However, longer term follow up and a greater number of patients are warranted before this experimental procedure is applicable to eyes that would do well with conventional surgery.