Safety and Efficacy of the Preserflo® Microshunt in Refractory Glaucoma: A One-Year Study

Efficacy, Confounders and Safety of the Preserflo Microshunt

BACKGROUND

Glaucoma is a leading cause of blindness worldwide. We evaluated the efficacy, confounders, and safety of the Preserflo Microshunt over a one-year follow-up period.

METHODS

In this retrospective monocentric study, 111 eyes were evaluated. 83 eyes had primary open angle glaucoma, and 28 eyes secondary open angle glaucoma. Intraocular pressure (IOP), visual acuity, number of glaucoma medications, complications, and reoperations were evaluated postoperatively, at 1, 3, 6, 9, and 12 months. The influence of age, sex, type of glaucoma, previous surgery and lens status was also analysed. Bleb revision was indicated if corrected IOP exceeded 18 mmHg.

RESULTS

Intraocular pressure significantly decreased from 24.50 ± 8.94 to 14.62 ± 4.86 mmHg (4 - 32 mmHg; p < 0.001), the number of medications from 3.19 ± 1.14 to 0.98 ± 1.39 (0 - 4; p < 0.001). Confounders of interest did not affect efficacy. Bleb revision was performed in 22.5% of eyes and a cyclophotocoagulation was performed in 9.9% of eyes. Complete surgical success (IOP ≤ 17 mmHg, IOP reduction ≥ 20%, without medication) was achieved in 36.9% (n = 41) and qualified success (with medication) in 51.4% (n = 57) of eyes. Transient hypotension (≤ 5 mmHg) occurred in 19.8% after primary implantation and in 1.8% after bleb revision (duration ≤ 3 months).

CONCLUSION

To date, the Preserflo Microshunt has demonstrated good efficacy and a low risk profile.

Long-term Outcomes of PreserFlo MicroShunt versus XEN45 Gel Stent in Open-Angle Glaucoma

PURPOSE

To compare two glaucoma drainage devices with subconjunctival filtration (MicroShunt and XEN) for open-angle glaucoma (OAG), with respect to effectiveness and safety.

PATIENTS AND METHODS

This is a single center, retrospective, interventional study. In total, 106 eyes of 95 patients with OAG underwent surgery. Of these patients, 51 eyes of 45 patients received a MicroShunt implantation and 55 eyes of 50 patients received an XEN implantation. Failure was defined as an intraocular pressure (IOP) lower than 5 or higher than 17 mmHg at the end of follow-up after 2 years, the need for surgical revision, secondary glaucoma surgery, or loss of light perception. Outcome was rated as complete success or qualified success, depending on whether it was achieved with or without anti-glaucomatous medications. Postoperative complications and interventions were also documented for both groups.

RESULTS

In the MicroShunt group, mean IOP decreased from 20.6 ± 7.5 mmHg at baseline to 13.0 ± 3.9 mmHg (p < 0.0001) after 2 years. In the XEN group, mean IOP was lowered from 22.5 ± 7.9 mmHg to 13.5 ± 4.2 mmHg (p < 0.0001). In both groups, the mean number of medications was significantly reduced (MicroShunt 2.7 ± 1.2 to 0.9 ± 2.5; p < 0.0001 vs. XEN 3.2 ± 0.9 to 1.1 ± 1.5; p < 0.0001). In regard to success rates, 37% of MicroShunt patients achieved complete success and 57% qualified success at the end of follow-up. In the XEN group, rates were 25 and 45%, respectively. Patient demographics differed between the two groups with respect to age (MicroShunt 72.8 ± 8.7 vs. XEN 67.7 ± 9.0 years; p = 0.002). Postoperative complications were comparable between the two groups.

CONCLUSION

Both MicroShunt and XEN are effective in significantly reducing IOP and glaucoma medications in OAG, and with a good safety profile.

Assessing the Impact of PRESERFLO MicroShunt on Intraocular Pressure in Porcine Eyes Ex Vivo Using Infusion Pump System

To evaluate the effectiveness of the PRESERFLO MicroShunt (PFM) in reducing intraocular pressure (IOP) ex vivo in porcine eyes using an infusion pump system and to simulate various IOP conditions, In this study, porcine eyes received increasing flows between 2 and 20 μL/min. IOP measurements were taken under conditions with and without the PFM [PFM (+) and PFM (-), respectively]. In the PFM (-) group, IOP increased from 7.4 mmHg to 46.3 mmHg as the flow rate increased from 2 μL/min to 20 μL/min. The rate of IOP reduction (%ΔIOP) rose with increasing flow rates, although the absolute IOP values achieved with the PFM insertion also increased. The correlation between IOPs in the PFM (-) conditions and the %ΔIOP was modeled as %ΔIOP = 22.4 Ln [PFM(-) IOP] - 41.7. According to this equation, IOP reduction by PFM insertion is 0% at IOPs of 6.4 mmHg or lower. IOP reductions of 10%, 20%, 30%, and 40% were observed when the pre-insertion IOPs were 10.1, 15.7, 24.6, and 38.4 mmHg, respectively. Achievable post-insertion IOP levels of ≤21 mmHg, ≤18 mmHg, ≤15 mmHg, and ≤12 mmHg corresponded to the initial IOPs of 33 mmHg, 26 mmHg, 20 mmHg, and 14.8 mmHg, respectively. In conclusion, the PFM effectively reduced IOP within a specific range of IOP values in an ex vivo experimental system. In clinical situations, the PFM is unlikely to be effective at low IOP levels. At higher levels, the PFM reduces IOP, but it may be insufficient to achieve the target IOP.

Comparing the safety and efficacy of Preserflo Microshunt implantation and trabeculectomy for glaucoma: A systematic review and meta-analysis

To compare the safety and efficacy of the Preserflo Microshunt with trabeculectomy in the treatment of patients with glaucoma. A systematic review and meta-analysis was conducted. The primary outcome measures recorded as a measure of efficacy of the interventions were intra-ocular pressure (IOP) at final follow-up and IOP reduction (IOPR). Secondary outcomes recorded to measure efficacy were reduction in the number of glaucoma medications and reinterventions. To assess safety profile, the proportions of patients with post-operative complications were recorded. Seven articles were included in this study. A total of 1353 eyes were included in this review (Preserflo: 812, trabeculectomy: 541). Post-operative IOP (mean difference [MD] = 0.78 [0.66, 0.90], p < 0.001) results are significantly lower for trabeculectomy than Preserflo. The IOPR (MD = -1.20 [-2.30, -0.09], p = 0.034) results significantly favour trabeculectomy over Preserflo Microshunt. The reduction in topical glaucoma medications (MD = -0.32 [-0.58, -0.07], p = 0.014) is significantly higher for trabeculectomy. There is no statistically significant difference in levels of hypotony (risk ratio [RR] = -0.05 [-0.47, 0.37], p = 0.806), choroidal effusion/detachment (RR = -0.12 [-0.42, 0.19], p = 0.444), hyphaema (RR = 0.20 [-0.11, 0.51], p = 0.216) and flat anterior chamber (RR = 0.49 [-1.02, 0.03], p = 0.066). There are significantly more bleb-related complications in the trabeculectomy groups than Preserflo groups (RR = -0.63 [-1.01, -0.24], p = 0.001). There were statistically more reinterventions required in the trabeculectomy groups than Preserflo groups (RR = -0.48 [-0.65, -0.30], p < 0.001). Compared to trabeculectomy, the Preserflo Microshunt is not as effective in lowering intra-ocular pressure, has a similar safety profile and has a lower reintervention rate. Further research is required given the lack of randomised controlled trials within this study and resulting low strength of evidence.

Standard anterior peritomy versus a small posterior incision for the implantation of the PRESERFLO microshunt

PURPOSE

To compare two approaches for the implantation of the PRESERFLO microshunt: an anterior approach (A) with a 6-8-mm peritomy and a posterior approach (P) with a 3-mm incision.

METHODS

We retrospectively analyzed 126 patients who received a PRESERFLO microshunt. We compared intraocular pressure (IOP), surgical time, medication count, and postoperative complications over nine months.

RESULTS

The baseline IOP was similar in A (21.8 ± 8.5 mm Hg) and P (23.9 ± 8.1 mm Hg) (p = 0.08). Surgical duration was significantly shorter in P (10 ± 0.4 min) than in A (26 ± 0.8 min) (p < 0.001). Postoperative IOP levels were comparable in A (10.8 ± 5.9 mm Hg) and P (10.6 ± 4.5 mm Hg) at 30 days (p = 0.62) and throughout the study (all intra-group p-values > 0.08). The preoperative medication count was 3.2 ± 1.3 drops in A and 3.3 ± 1.0 drops in P (p = 0.4). Postoperative values were 0.2 ± 0.6 in A and 0.3 ± 0.7 in P at nine months. There were no significant differences in complications and surgical revisions between groups (p-values > 0.05).

CONCLUSION

Both techniques achieved satisfactory IOP and medication count reductions and had similar safety profiles, but the posterior incision technique was 2.6 times faster than the anterior incision technique.

[Review by the French Glaucoma Society on the roles of new surgical techniques in glaucoma]

The surgical management of glaucoma has been enriched in recent years by the arrival of new surgical techniques as a group known as MIGS (minimally invasive glaucoma surgery). The objective of these new techniques is to reduce intraocular pressure (IOP) while limiting the risk of complications of conventional filtering surgery and allowing faster visual recovery. MIGS can be classified into three main categories depending on the route used to promote the outflow of aqueous humor: the trabecular route, the suprachoroidal route and the subconjunctival route. MIGS using the subconjunctival route are also called minimally invasive bleb surgery (MIBS). These new techniques do not replace conventional filtering surgery, which remains the gold standard technique, but now offer new alternatives for the surgical management of glaucoma patients in combination with cataract surgery or as stand-alone procedures.

Minimally Invasive Glaucoma Surgery: Latest Developments and Future Challenges

The development of minimally invasive glaucoma surgeries (MIGSs) was intended to provide safe and modestly efficacious modalities for early intervention of mild-to-moderate glaucoma, with minimal trauma and rapid recovery. They were mainly ab interno procedures that reduce intraocular pressure by facilitating the aqueous outflow by bypassing the trabecular meshwork resistance, reinforcing the uveoscleral flow via the supraciliary space, and reducing aqueous production by the ciliary body. While the cumulating evidence helps shape the role of the available MIGS, the exponential new development and advancement in this field has expanded the territory of MIGS. Apart from developing subconjunctival MIGS filtration devices (Xen gel stent and PRESERFLO MicroShunt), there is a tendency to revisit the "traditional" MIGS for alternative use and to modify the procedures with consideration of the fundamental aqueous outflow physiology. Combined MIGS has also been suggested, based on the theory that their different mechanisms may provide additive or synergistic effects. The advancement of laser procedures is also promising and could supplement unmet needs along the glaucoma treatment algorithm. This review examines the broad array of MIGS, updates the recent findings, discusses their potential alternative applications, and explores future challenges.