The Efficacy of Ab Externo Canaloplasty by Using a Nonabsorbable Suture and No Viscoelastics; IOP Results, Intraoperative and Early Complication Rates within 6-Month Follow-Up Period.

Abstract

To report the efficacy of ab externo canaloplasty by exclusively using only a nonabsorbable suture as a standalone operation or combined with phacoemulsification in terms of mean intraocular pressure (IOP), medication reduction, and intra- and postoperative complication rates as well as additional glaucoma surgery. Forty-eight patients with primary open-angle glaucoma (POAG) and 50 eyes were divided into two groups according to the operation performed (Group A canaloplasty, n = 34 and Group B canaloplasty combined with phaco, n = 16), respectively. The success criteria were evaluated between three IOP ranges: a) IOP ≤ 16 mmHg, b)≤ 18 mmHg, and c) ≤ 21 mmHg. Complete success was considered the percentage of eyes reaching these goals with no medication and qualified success with or without medication. Groups A and B were compared with the Kaplan-Meier test. Mean IOP and medication reduction as well as additional glaucoma surgery were also evaluated. The follow-up time was 6 months. Statistical importance was given at p < 0.05. Fail rate and intraoperative conversion of canaloplasty to other surgery (trabeculotomy due to extensive cheese-wiring) accounted for 12% (6 eyes), while a mandatory usage of the iTrack 250A microcatheter to successfully overcome intracanalicular bridging of the Schlemm's canal accounted for 20% (10 eyes). The most common early postoperative complications in both groups were hyphema, cheese wiring, and transient IOP rising. The mean IOP in Group A reduced from 23.67 ± 6.06 mmHg to 13.35 ± 4.23 mmHg and in Group B, it reduced from 23.55 ± 6.19 mmHg to 12.75 ± 1.5 mmHg at 6months (p < 0.001). Group A's absolute success rates accounted for a)44%, b)47.1%, and c) 52.9% in comparison to Group B [a) 50%, b)50%, and c) 56.3%] at 6 months (p < 0.05). Qualified success with or without medication showed no statistical differences between the groups. The mean medication reduction was significantly lower (p < 0.001) in both groups (Group A from baseline 3.2 ± 1.23 to 0.95 ± 1.35 and Group B from 3.12 ± 0.88 to 1.12 ± 0.75 at 6 months, respectively). Five eyes (10%) required additional glaucoma surgery. Ab externo canaloplasty by exclusively using only a nonabsorbable suture as a standalone operation or combined with phacoemulsification seems to lower the mean IOP and medication sufficiently. However, they pose a greater surgical challenge and intraoperative complication rate. Additional glaucoma surgery or medication following both procedures may be necessary to achieve an optimal target IOP.