Standalone Versus Combined Phacoemulsification Preserflo® Microshunt Implantation: A 12-Month Comparative Study Of Efficacy And Safety

The PRESERFLO® MicroShunt is a subconjunctival bleb-forming device that has demonstrated consistent efficacy in reducing intraocular pressure (IOP) in patients with glaucoma, potentially offering greater IOP reduction than other minimally invasive glaucoma procedures and a lower risk of hypotony compared to trabeculectomy. It can be implanted alone or combined with cataract surgery. Current evidence indicates that both significantly reduce IOP and medication burden, with comparable safety and similar success rates at 12 months in open-angle glaucoma. This study aimed to evaluate and compare the efficacy and safety of standalone (group 1) versus combined (group 2) PRESERFLO implantation over 12 months in a Portuguese tertiary hospital.

This retrospective study was conducted at a tertiary referral hospital in Braga, Portugal.

This study included 47 eyes of 38 patients undergoing PRESERFLO implantation with mitomycin C 0.4 mg/mL at Hospital de Braga, between 2023 and 2025. Combined cataract surgery was performed in 15 eyes (31.9%). Data collected included demographics, glaucoma subtype, IOP, number of hypotensive medications, best-corrected visual acuity (BCVA), perimetric mean deviation (MD), retinal nerve fiber layer (RNFL) thickness, and postoperative complications. Follow-up visits were scheduled at 1 week, and 1, 3, 6, and 12 months. Surgical outcomes were classified as complete success, qualified success, or failure.

Standalone PRESERFLO implantation was performed in 32 eyes and combined surgery in 15 eyes. Both groups were comparable regarding the mean age, baseline IOP (23.3±7.0 vs 20.1±4.8 mmHg, p=0.120) and nº of hypotensive medications (2.78±0.98 vs 2.67±1.05, p=0.715). Group 1 had less POAG cases (53% vs 73%) and less treatment naïve eyes (62.5% vs 80%). In the 1^st week, IOP significantly reduced in both groups (9.72±8.0mmHg, -57% in group 1 and 9.80±3.9mmHg, -47% in group 2), without inter-group differences (p=0.226). At 12 months of follow-up, IOP was significantly lower in group 1 (12.2±2.1 vs 15,9±1.8mmHg, p<0.001), with a mean change of -47% (vs -21%). Surgical failure, medications, BCVA, MD and RNFL thickness were similar between groups.

Standalone and combined PRESERFLO® MicroShunt implantation achieved significant IOP reduction at 12 months, with comparable safety and similar success rates. Although early postoperative IOP reduction was similar, standalone surgery was associated with lower mean IOP and greater percentage reduction at 12 months. Medication burden, visual and structural outcomes, and complication rates did not differ significantly between groups. These findings support the effectiveness of both approaches, while suggesting a potential advantage of isolated implantation in long-term IOP control. However, the small sample size limits the strength of these conclusions and warrants confirmation in larger prospective studies.