The effect of the extent of the incision in the Schlemm canal on the surgical outcomes of suture trabeculotomy for open-angle glaucoma

Abstract

Purpose: To examine the relationship between the extent of the incision in the Schlemm canal during suture trabeculotomy (S-LOT) for open-angle glaucoma and the associated reduction in intraocular pressure (IOP).

Methods: Forty-eight consecutive eyes (primary open-angle glaucoma: 28; exfoliation glaucoma: 20) scheduled to undergo S-LOT were studied. A 320-degree opening in the Schlemm canal was planned when total circumferential cannulation had been achieved, and the remaining 40-degree region under the scleral flap was not incised. When the cannulation was incomplete, the canal was incised up to the point reached by the cannula, and the extent of the incision was measured. Logistic regression analysis was performed to identify potential predictors of surgical success (IOP ≤ 15 mmHg).

Results: A 320-degree incision was achieved in 23 eyes, and the mean extent of the incision was 275 ± 52.3°. The mean IOP fell from 34.0 ± 8.8 mmHg at baseline to 14.5 ± 4.0 mmHg at 1 year postoperatively (P < 0.0001). An IOP reduction of ≥30% was achieved in 46 eyes. Simple correlation analysis indicated that the extent of the incision in degrees did not correlate with IOP or with the reduction in IOP at 1 year postoperatively (P = 0.7665 and 0.693, respectively). Lower preoperative IOP values and concomitant cataract extraction were found to be associated with surgical success.

Conclusions: The extent of the incision in the Schlemm canal during S-LOT does not correlate with postoperative reduction in IOP.

Keywords: Cataract extraction; IOP reduction; Incision extent; Open-angle glaucoma; Trabeculotomy.