[Effect of suture canalization on the treatment of primary open-angle glaucoma: 3 years clinical observation].

OBJECTIVE: To evaluate the safety and effectiveness of the Suture Canalization, which is a kind of Schlemm canal surgery, on the treatment of patients with primary open angle glaucoma (POAG).

METHODS: Retrospective cases series study. Fifty-two patients (52 eyes) with POAG were recruited from October 2007 to July 2009 from Hospital of Optometry and Ophthalmology, Wenzhou Medical University. Twenty-six patients (26 eyes) were included in the study group, who were treated with the Suture Canalization surgery with trabeculectomy. Twenty-six patients (26 eyes) were included as the control group, who were treated with trabeculectomy only. Best correct visual acuity (BCVA), intraocular pressure (IOP), bleb morphology, postoperative treatment of medicine of anti-glaucoma and complications of surgery were recorded at 1 d, 1 week, 1, 3, 6, 12, 18, 24, 30 and 36 months after surgery. After testing the normality and homogeneity of variance of the data of the multiple sets of measurement data, the variance analysis was adopted, and the t test was used in the comparison of two groups. Counting data using chi-square test, the level of variables between the groups should be compared with the rank sum test.

RESULTS: No significant difference was found in baseline data, as well as the changes of BCVA between the study group and control group at the last visit (χ(2)=3.06, P=0.08) . Complete and qualified success was achieved in 18 (69.2%) and 23 (88.5%) cases separately in study group, 16 (61.5%) and 22 (84.6%) cases separately in control group (χ(2)=0.17, P=0.69) . There was no significant difference between two groups. IOP was decreased post-operatively: from (32.4±9.3) mmHg(1 mmHg=0.133 kPa)to (16.9±3.5) mmHg at the last visit in study group and (31.3±10.0) mmHg to (15.5±4.6) mmHg at the last visit in control group. There were significant difference between last visit and preoperative IOP between two groups (study group: t=8.12, P<0.01; control group: t=7.20, P<0.01). No significant difference was found between two groups in the decreased amplitude of IOP with treatment at the last visit (t=0.23, P=0.63), as well as the postoperative IOP at the different visits (P>0.05). 65.4% of cases in the study group and 61.5% patients in control group formed functional blebs (diffuse type and microcapsule type) at the last visit. No significant difference between the IOP of patients with functional blebs (15.5±3.5) mmHg and those with non-functional blebs (16.0±3.4) mmHg in study group at the last visit (t=-0.49, P=0.64). No serious complications during and after surgery were found in subjects of the both groups. No significant difference was present in medicine amounts at last visit between the two groups (t=2.93, P=0.09).

CONCLUSIONS: Suture Canalization is a safe and effective surgical procedure to decrease intraocular pressure in patients with POAG, through Schlemm canal and external filtration. While it maybe not suitable to the patient with high pre-operative IOP.(Chin J OPhthalmol, 2016, 52: 416-421).