Efficacy of Intraoperative 9-0 Nylon Thread Insertion for Preventing Hypotony-Related Complications Following PreserFlo MicroShunt Implantation in Japanese Patients: A Comparative Study.

BACKGROUND

Early postoperative hypotony remains a significant complication following PreserFlo MicroShunt (PMS) implantation, potentially leading to serious sequelae including choroidal detachment and hypotensive maculopathy. This study evaluated the effectiveness of intraoperative 9-0 nylon thread insertion (NTI) technique in preventing hypotony-related complications.

METHODS

This retrospective comparative study included 81 eyes of 63 patients who underwent PMS implantation with mitomycin C between September 2023 and June 2025. Eyes were divided into NTI group (59 eyes, 42 patients) and Non-NTI group (22 eyes, 21 patients). The primary outcome was the incidence of composite hypotony-related complications (choroidal detachment and/or hypotensive maculopathy) during 6-month follow-up. Secondary outcomes included intraocular pressure (IOP) changes, medication score reduction, and timing of suture removal. Statistical analyses incorporated cluster correction for bilateral cases.

RESULTS

Baseline characteristics, including glaucoma subtype distribution, were comparable between groups. The composite hypotony-related complication rate was significantly lower in the NTI group (11.9% vs 54.5%, p<0.001; odds ratio 0.112, 95% CI 0.039-0.321). Kaplan-Meier analysis demonstrated superior complication-free survival in the NTI group (log-rank p<0.001, hazard ratio 0.094, 95% CI 0.035-0.252). The median IOP at postoperative day 1 was significantly higher in the NTI group (10.0 [8.0-14.0] vs 5.8 [5.0-8.5] mmHg, p<0.001), indicating effective early hypotony prevention. At 6 months, both groups achieved comparable IOP control (13.0 [10.9-14.0] vs 13.0 [11.0-16.0] mmHg, p=0.324) with medication-free rates of 74.6% and 59.1%, respectively (p=0.190).

CONCLUSION

Intraoperative 9-0 nylon thread insertion significantly reduces hypotony-related complications following PMS implantation without compromising IOP control at 6 months or medication reduction, representing a safe and effective surgical modification.