Ab Externo SIBS Microshunt with Mitomycin C for Open-Angle Glaucoma: Three-Year Results as a Primary Surgical Intervention

PRESERFLO MicroShunt in Severe Myopia: A Case Report and Review of the Literature

The PRESERFLO™ MicroShunt (MP; Santen Inc., Osaka, Japan) is a minimally invasive bleb surgery (MIBS) manufactured to treat primary open-angle glaucoma (POAG), with lower postoperative adverse effects than with conventional filtering surgeries. We describe here the case study of a 58-year-old woman who presented with bilateral severe myopia with bilateral advanced POAG and unreached target pressure under quadritherapy, who was successfully managed by PM surgery. A review of the literature completes our observation. At presentation, the patient had a spherical equivalent of - 7.50 RE and - 7.75 LE with an IOP of 22 mmHg right and left eye (RLE) under quadritherapy, and with severe bilateral visual field loss, including scotomas within the central 5°. The patient presented with systemic hypertension treated with an antihypertensive drug. Two selective laser trabeculoplasties (SLT), performed 3 months apart, were first tried on the LE, without any change in IOP at 2 months. After considering the high risk of postoperative complications, a PM operation was proposed, with a targeted IOP in the mid-fifteens RLE. The patient's eyes underwent PM surgery with mitomycin C (MMC) MMC0.2 mg/mL for 3 minutes without any complications. The LE required 2 consecutive needlings with 1 mL MMC0.2 mg/mL. At 24 months after surgery, the two eyes gave successful results without the need for any additional medical therapy, and with well-functioning conjunctival blebs. The PM was an effective alternative to the gold standard trabeculectomy in our severely myopic patient. A comparative study between conventional filtering operations and this MIBS in highly myopic patients would confirm our observation.

Difficult decisions, filtration surgery, and the heartbreak of the numerator

A 70-year-old man had progressive and severe glaucoma in each eye. He was intolerant to dorzolamide, brimonidine, and netarsudil. Each eye had prior selective laser trabeculoplasty (SLT) as well as phacoemulsification plus minimally invasive glaucoma surgery (MIGS) 6 years before current presentation (iStent [Glaukos Corp.] in the right eye and Cypass [Alcon Laboratories, Inc.] in the left eye). Postoperative acuities were 20/20 and 20/25 in the right and left eyes, respectively. When his left eye progressed with loss of central acuity despite peak intraocular pressures (IOPs) in the middle to upper teens, neuro-ophthalmology consultation was obtained (Figure 1JOURNAL/jcrs/04.03/02158034-202401000-00017/figure1/v/2023-12-22T124801Z/r/image-tiff). That workup included magnetic resonance imaging scan and hematologic screening, but all results were negative, and the neuro-ophthalmic consultant concluded that the vision loss was likely on the basis of glaucoma. Accordingly, a trabeculectomy was performed in the left eye achieving consistent IOPs in the range of 7 to 10 mm Hg without medications, rending the left eye stable since the filtration surgery nearly 2 years previously. The right eye continued to progress both subjectively and objectively, and on recent examination, the IOP measured 20 mm Hg and 09 mm Hg in the right and left eyes, respectively (Figure 2JOURNAL/jcrs/04.03/02158034-202401000-00017/figure2/v/2023-12-22T124801Z/r/image-tiff). Medications included timolol and latanoprostene bunod in the right eye only. Central corneal thickness was 526 μm and 527 μm in the right and left eyes, respectively. The visual acuity now measured 20/25 in the right eye and 20/250 in the left eye. The vertical cup-to-disc ratio was 0.9 in the right eye and 1.0 in the left eye. Gonioscopy revealed a wide open angle in each eye with a patent sclerostomy superiorly in the left eye. The conjunctiva and sclera were healthy and without scarring in the right eye. The bleb in the left eye was diffuse, lightly vascularized, and seidel negative. Axial length (AL) was 26.88 μm in the right eye and 26.77 μm in the left eye. The patient was in good health and was not anticoagulated. An extensive discussion ensued about the best course of action for the right eye. How would you proceed in managing definite progression in this individual's right eye, knowing that he had lost fixation in his left eye at similar pressures?

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.

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.