PreserFlo® MicroShunt: An Overview of This Minimally Invasive Device for Open-Angle Glaucoma

Visualization of the Postoperative Position of the Hydrus® Microstent Using Automatic 360° Gonioscopy

Introduction: Glaucoma, one leading cause of irreversible vision loss worldwide, is primarily caused by elevated intraocular pressure (IOP). Recently, minimally invasive glaucoma surgeries (MIGSs) have become popular due to their shorter surgical times, tissue-sparing nature, and faster recovery. One such MIGS, the Hydrus® nickel-titanium alloy Microstent, helps lower IOP by improving aqueous humor outflow. The NIDEK GS-1 automated 360° gonioscope provides advanced imaging of the chamber angle for evaluation and documentation. The aim of this study was to test automated 360° gonioscopy for the detection of postoperative positional variations after Hydrus® Microstent implantation. This study is the largest to date to evaluate post-op positioning of the Hydrus® Microstent using the NIDEK GS-1. Materials and Methods: This study analyzed postoperative outcomes and stent location in eyes diagnosed with mild to moderate glaucoma that underwent Hydrus® Microstent implantation with or without phacoemulsification. Patients with prior IOP-lowering surgery or vitrectomy were excluded. Analyses of the postoperative Hydrus® Microstent position were based on the evaluation of automated 360° gonioscopy images. Results: Twenty-three eyes were included in the study, and all showed a reduction in IOP and a decrease in antiglaucomatous drop use postoperatively. Postoperative gonoscopic images showed variations in implant position. In all cases, the proximal inlet was clearly visible in the anterior chamber. The degree of protrusion into the anterior chamber was variable. The distal tip of the stent was visible behind the trabecular meshwork in Schlemm's canal in five cases, in the anterior chamber in one case, and not visible in seven cases. In no case did postoperative alterations in the position of the implant lead to explantation. Conclusions: This study demonstrated that the Hydrus® Microstent can effectively lower IOP even in the presence of postoperative positional variations. Automated 360° gonioscopy was found to be a useful tool to verify and document the postoperative position of the implant. Positional changes did not require device explantation in any of the cases evaluated.

Efficacy and Safety of PreserFlo MicroShunt Implantation and Its Effects on Intraocular Inflammation through Laser Flare Photometry

Purpose

The primary objective of this study is to evaluate the efficacy and safety profile of PreserFlo MicroShunt implantation in the medium- to long-term follow-up of patients with open-angle glaucoma. The secondary objective is to analyze laser flare meter (LFM) values before and after PreserFlo MicroShunt implantation.

Methods

This prospective, observational, longitudinal single-center study included a total of 62 eyes from 54 patients. A subgroup of 27 eyes (26 patients) reached the 12-month follow-up. Success was defined based on three criteria: criterion A: IOP ≤21 mmHg and ≥20% reduction; criterion B: IOP ≤15 mmHg and ≥25% reduction; and criterion C: IOP ≤12 mmHg and ≥30% reduction. Success was further categorized as complete if achieved without IOP-lowering medications and qualified if achieved with medication administration. Other aspects evaluated included the number of IOP-lowering medications (baseline and postoperative), development of postoperative complications, 5-FU injections or implant revision, and LFM values.

Results

The 12-month follow-up group (27 patients) was composed by 50% males and had a mean age of 75.54 ± 9.98 years. Success rates at 12 months were as follows: 78% for criterion A, 56% for criterion B, and 26% for criterion C. Complete success, as defined by criterion A, was achieved by 67% of the patients, 29% achieved qualified success, and one eye (4%) experienced failure. IOP decreased from 25.26 ± 1.67 mmHg at baseline to 14.81 ± 0.74 mmHg at 12 months. The number of medications decreased from 3.67 ± 1.30 at baseline to 0.48 ± 0.75 at 12 months. Reported complications were choroidal detachment (11%), hyphema (5%), and athalamia (flat anterior chamber) (2%) 13 eyes (48%) received 5-FU injections, while 7 eyes (26%) underwent implant revision. No significant increase in LFM values was observed. Eyes with a regular postoperative course and IOP ≤15 mmHg showed significantly lower LFM values than patients with unfavorable outcomes (IOP >15 mmHg, development of complications, 5-FU injection, or implant revision).

Conclusions

PreserFlo MicroShunt showed a significant reduction in IOP and a decrease in the number of IOP-lowering medications. Complications occurred at a modest frequency. The implant provides a minimally invasive approach with no significant increases in LFM values postoperatively. Higher LFM values correlate with unfavorable postoperative outcomes.

Intermediate-term impact on corneal endothelial cells and efficacy of Preserflo MicroShunt implantation in patients with open-angle glaucoma - a prospective study over two years

INTRODUCTION

Preserflo MicroShunt is a novel microinvasive bleb forming device for the treatment of primary open-angle glaucoma. The intermediate- and long-term success and the impact of this procedure on corneal endothelial cell density remain to be investigated.

METHODS

In this prospective observational study, 62 eyes of 55 glaucoma patients (mean age ± SD: 67.0 ± 15.0 years) receiving a Preserflo MicroShunt were included. Corneal endothelial cell density, intraocular pressure and best corrected visual acuity were assessed preoperatively and at 3, 6, 9, 12, 18 and 24 months postoperatively. Success rates, bleb revision rates and complications were analysed. Complete success was defined as an intraocular pressure reduction of ≥ 20% and achieving a target pressure of ≤ 18, ≤ 15 or ≤ 12 mmHg without antiglaucoma medication. Qualified success indicated that the criteria were reached with or without medication.

RESULTS

Corneal endothelial cells showed no significant decline over 24 months (p > 0.05). Intraocular pressure showed a substantial reduction postoperatively (p < 0.001), decreasing from 29.6 ± 8,3 mmHg to 13.0 ± 4.3 mmHg after 24 months (p < 0.001). Complete and qualified success with a target pressure ≤ 15 mmHg was achieved in 52.9% and 54.6% of cases after 24 months, respectively. Best corrected visual acuity did not change after 24 months.

CONCLUSION

Preserflo MicroShunt had no negative side effects on corneal endothelial cells and showed favourable success rates after 2 years in patients with open-angle glaucoma.

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.

Hypotony in the early postoperative period after MicroShunt implantation versus trabeculectomy: A registry study

PURPOSE

A comparison of the safety and efficacy of the MicroShunt versus trabeculectomy in the early postoperative period, with a particular focus on hypotony.

METHODS

In this registry study, we evaluated 200 eyes of 200 glaucoma patients who underwent filtration surgery at Oslo University Hospital between 2017 and 2021. Of these patients, 100 had a Preserflo MicroShunt (Santen) implantation and 100 had a trabeculectomy procedure. The patients were examined per standard hospital protocol after filtration surgery. Data were extracted from the 4- and 8-week visits. We defined hypotony as intraocular pressure (IOP) < 6 mmHg.

RESULTS

The mean preoperative IOP was 20.6 ± 7.1 mmHg in the MicroShunt group and 21.6 ± 7.1 mmHg in the trabeculectomy group, and the patients used a mean of 3.0 ± 0.9 and 3.1 ± 0.9 glaucoma medications, respectively. After 8 weeks, IOP was reduced to 10.4 ± 5.4 mmHg and 11.3 ± 4.6 mmHg, respectively (p = 0.23). During the early postoperative period, hypotony was registered in 63% of the MicroShunt patients and in 21% of the patients in the trabeculectomy group (p < 0.001); and 11% and 1%, respectively, of the patients developed choroidal detachments (p < 0.003). One patient in the MicroShunt group required reoperation due to hypotony.

CONCLUSIONS

In this registry study, we found that the Preserflo MicroShunt and trabeculectomy had equally satisfactory IOP-lowering effects during the early postoperative period. In this same period, a high number of patients in the MicroShunt group developed hypotony.

Update on Diagnosis and Treatment of Uveitic Glaucoma

Glaucoma is a common and potentially blinding complication of uveitis. Many mechanisms are involved alone or in combination in the pathogenesis of uveitic glaucoma (UG). In terms of diagnostic evaluation, the effects of inflammatory activity in the retinal nerve fiber layer may be a source of bias in the interpretation of optical coherence tomography measurements. For the successful treatment of UG, the control of intraocular inflammation specific to the cause or anti-inflammatory treatment, combined with IOP management, is mandatory. The early institution of specific treatment improves the prognosis of UG associated with CMV. The young age of UG patients along with increased failure rates of glaucoma surgery in this group of patients warrants a stepwise approach. Conservative and conjunctival sparing surgical approaches should be adopted. Minimally invasive surgical approaches were proved to be effective and are increasingly being used in the management of UG along with the traditionally used techniques of trabeculectomy or tubes. This review aims to summarize the progress that recently occurred in the diagnosis and treatment of UG.

Evaluation of ocular surface following PreserFlo Microshunt implantation: Functional outcomes and quality of life

BACKGROUND

This study aimed to evaluate the impact of PreserFlo Microshunt on the ocular surface, focusing on both objective and subjective parameters.

METHODS

Prospective-observational study on 48 eyes undergoing PreserFlo Microshunt implantation, standalone or combined with phacoemulsification. At baseline, 1-month, 6-months and 12-months post-operative follow-ups, we performed Ocular Surface Disease Index (OSDI) questionnaire, Schirmer's test (ST), Tear-film break-up time (TBUT), fluoresceine staining (FS), tear osmolarity and minimum corneal epithelial thickness (Epi-ThkMIN. ) measurements.

RESULTS

OSDI score improved from 37.43 ± 17.49 at baseline, to 24.13 ± 12.55 at 1-month (p = 0.003) and to 12.89 ± 8.54 and 13.09 ± 10.22 at 6-months and 12-months (p < 0.0001). TBUT and ST, in a similar way, non-significantly increased at 1-month, but then improved at 6-months and 12-months (p < 0.05 for both). Tear osmolarity significantly decreased from 308.2 ± 7.3 mOsm/L at baseline, to 303.3 ± 8.2 mOsm/L, 295.6.2 ± 7.0 mOsm/L and 297.6 ± 6.8 mOsm/L at 1-month, 6-months and 12-months (p < 0.05 for all). Epi-ThkMIN was stable when comparing baseline (44.9 ± 5.7 μm) and 1-month (p = 0.28), and successively increased in 6-months (47.8 ± 5.5 μm, p = 0.02) and 12-months (48.0 ± 3.6 μm, p = 0.01). In subgroup analysis, OSDI score and tear osmolarity were significantly higher at 1-month in combined group compared to standalone group (p = 0.03 and p = 0.02, respectively), but reaching comparable values in successive follow-ups. Further, Oxford scale grades for FS were significantly improved when comparing baseline-6-months and baseline-12-months.

CONCLUSION

PreserFlo implantation improved ocular surface subjective symptoms, increased TBUT and ST, and reduced FS, highlighting the potential benefits of this surgical intervention. Moreover, we reported significant improvements of tear osmolarity and corneal epithelium.

PRESERFLO MicroShunt implantation versus trabeculectomy for primary open-angle glaucoma: a two-year follow-up study

BACKGROUND

To compare the intermediate-term efficacy of PRESERFLO (PF) MicroShunt implantation with trabeculectomy (TE) in patients with primary open-angle glaucoma, focusing on longitudinal changes of functional and structural parameters.

METHODS

This retrospective comparative study included 104 eyes of 104 patients who underwent TE and 83 eyes of 83 patients that underwent PF implantation between January 2019 and December 2020, with a minimum follow-up of two years. Baseline and postoperative intraocular pressure (IOP), number of IOP-lowering medications, visual field mean defect (MD) and peripapillary retinal nerve fibre layer (RNFL) thickness measured using optical coherence tomography were assessed and compared between groups.

RESULTS

Baseline characteristics (age, sex, IOP, number of IOP-lowering medications, MD, RNFL thickness) were comparable between the two groups (all P > 0.05). During the two-year of follow-up, mean IOP decreased from 24.09 ± 1.15 mmHg and 21.67 ± 0.77 mmHg to 11.37 ± 1.13 mmHg (P < 0.001) and 15.50 ± 1.54 mmHg (P = 0.028), and the mean number of IOP-lowering medications decreased from 3.25 ± 0.14 and 3.51 ± 0.14 to 0.53 ± 0.14 (P < 0.001) and 1.06 ± 0.43 (P < 0.001) in the TE and PF groups, respectively. MD remained stable [- 11.54 ± 0.93 dB and - 11.17 ± 1.66 to - 10.67 ± 0.91 dB (P = 0.226) and - 10.40 ± 4.75 dB (P = 0.628) in the TE and PF groups, respectively] but RNFL thickness decreased continuously during follow-up [62.79 ± 1.94 µm and 62.62 ± 2.05 µm to 57.41 ± 1.81 µm (P < 0.001) and 60.22 ± 1.98 µm (P = 0.182) in the TE and PF groups, respectively].

CONCLUSION

PF implantation is comparably effective in the intermediate term in lowering IOP and reducing the use of IOP-lowering medications over a two-year follow-up period. Although visual field defects were stable, RNFL continued to decrease during postoperative follow-up.

The Preserflo MicroShunt Affects Microvascular Flow Density in Optical Coherence Tomography Angiography

Intraocular pressure (IOP) lowering surgery has been shown to alter microvascular density in glaucoma patients. The aim of this study is to report changes in retinal flow density (FD) over the course of treatment with the Preserflo MicroShunt, using optical coherence tomography angiography (OCTA). 34 eyes from 34 patients who underwent Preserflo MicroShunt implantation were prospectively enrolled in this study. OCTA imaging was conducted at the superficial (SCP), deep (DCP) and radial peripapillary plexus (RPC) levels. The progression of FD and IOP was assessed at different time points from baseline to six months postoperatively for the entire patient population, as well as disease severity subgroups. The Preserflo MicroShunt achieved a significant reduction in IOP over the course of six months (median: 8 mmHg; p < 0.01). FD values of the SCP and DCP did not show significant fluctuations, even after adjusting for disease severity. FD of the RPC decreased significantly over the course of six months postoperatively from 42.31 at baseline to 39.59 at six months postoperatively (p < 0.01). The decrease in peripapillary FD was strongest in patients with advanced glaucoma (median: -3.58). These observations hint towards dysfunctional autoregulatory mechanisms in capillaries surrounding the optic nerve head in advanced glaucoma. In comparison, the microvascular structure of the macula appeared more resilient to changes in IOP.

Development and material characteristics of glaucoma surgical implants

Background

Glaucoma is the leading cause of irreversible blindness worldwide. The reduction of intraocular pressure has proved to be the only factor which can be modified in the treatment, and surgical management is one of the important methods for the treatment of glaucoma patients.

Main text

In order to increase aqueous humor outflow and further reduce intraocular pressure, various drainage implants have been designed and applied in clinical practice. From initial Molteno, Baerveldt and Ahmed glaucoma implants to the Ahmed ClearPath device, Paul glaucoma implant, EX-PRESS and the eyeWatch implant, to iStent, Hydrus, XEN, PreserFlo, Cypass, SOLX Gold Shunt, etc., glaucoma surgical implants are currently undergoing a massive transformation on their structures and performances. Multitudinous materials have been used to produce these implants, from original silicone and porous polyethylene, to gelatin, stainless steel, SIBS, titanium, nitinol and even 24-carat gold. Moreover, the material geometry, size, rigidity, biocompatibility and mechanism (valved versus nonvalved) among these implants are markedly different. In this review, we discussed the development and material characteristics of both conventional glaucoma drainage devices and more recent implants, such as the eyeWatch and the new minimally invasive glaucoma surgery (MIGS) devices.

Conclusions

Although different in design and materials, these delicate glaucoma surgical implants have widely expanded the glaucoma surgical methods, and improved the success rate and safety of glaucoma surgery significantly. However, all of these glaucoma surgical implants have various limitations and should be used for different glaucoma patients at different conditions.

Minimally Invasive Glaucoma Surgery: A Review of the Literature

Minimally invasive glaucoma surgery (MIGS) has emerged as a novel approach in the glaucoma treatment spectrum, offering a range of diverse procedures and devices aimed at reducing intraocular pressure (IOP). MIGS can be broadly classified into several categories: those that enhance trabecular outflow (Trabectome, iStent, Hydrus Microstent, Kahook Dual Blade, high frequency deep sclerotomy, and gonioscopy-assisted transluminal trabeculotomy), those that augment suprachoroidal outflow (CyPass Microstent and iStent Supra), those that target Schlemm's canal (TRAB360 and the OMNI Surgical System, Streamline, and Ab Interno Canaloplasty), and conjunctival bleb-forming procedures (EX-PRESS Glaucoma Filtration Device, Xen Gel Stent and PreserFlo MicroShunt). MIGS is considered to have a shorter surgical time and fewer severe complications when compared to traditional glaucoma surgeries such as trabeculectomy and glaucoma drainage device implantation (Ahmed, Baerveldt, and Molteno valves). This literature review comprehensively examines the distinct MIGS devices and procedures, their underlying mechanisms, and clinical outcomes, emphasizing the importance of evaluating the efficacy and complications of each approach individually. As the field of MIGS continues to evolve, it is crucial to prioritize high-quality, long-term studies to better understand the safety and effectiveness of these innovative interventions in glaucoma management.

Intraoperative primary partial occlusion of the PreserFlo MicroShunt to prevent initial postoperative hypotony

PURPOSE

The aim of the underlying study was to present a new surgical method in PreserFlo MicroShunt surgery for glaucoma. A removable polyamide suture was placed into the lumen of the MicroShunt during implantation to prevent early postoperative hypotony.

METHODS

Thirty-one patients undergoing stand-alone glaucoma surgery with implantation of a PreserFlo MicroShunt and an intraluminal occlusion were retrospectively reviewed and compared to a control group without occlusion. Inclusion criteria were diagnosis of primary open-angle glaucoma or secondary open-angle glaucoma due to pseudoexfoliation or pigment dispersion. Patients with a history of filtrating glaucoma surgery were excluded.

RESULTS

IOP decreased from 26.9 ± 6.6 to 18.0 ± 9.5 mmHg at the first postoperative day after PreserFlo MicroShunt implantation. Postoperative removal of the occluding suture resulted in a mean IOP reduction in 11.1 ± 7.6 mmHg. Mean visual acuity was 0.43 ± 0.24 logMAR during the first postoperative examination. The interval with the occluding intraluminal suture in place varied from days to 2-3 weeks. Patients were followed up to 1 year.

CONCLUSION

Implantation of a PreserFlo MicroShunt combined with an intraluminal suture prevented postoperative hypotony in all patients. Mean postoperative pressure was reduced despite the occluding suture in place.

Long-Term Outcomes of the PRESERFLO MicroShunt Implant in a Heterogeneous Glaucoma Cohort

The Preserflo MicroShunt represents a novel glaucoma treatment device, necessitating long-term follow-up data to accurately assess its efficacy. The aim of this study is to report real-world data of a heterogenous glaucoma cohort who received Preserflo implantation at a specialized glaucoma clinic. A total of 160 eyes of 160 patients who underwent Preserflo MicroShunt implantation were retrospectively enrolled in this study. Patient characteristics, as well as success and failure rates, were assessed. The numbers of adverse events and revision procedures were recorded, along with any reduction in supplementary medication. The progression of intraocular pressure (IOP) was assessed over the course of 12 months, and fluctuations were analyzed. The overall success rate was 61.9% (complete success: 51.3%, qualified success: 10.6%). Revision surgery was performed in 25% of cases. Excessive hypotony occurred postoperatively in 54.4% of patients and regressed after 7 days in 88.8% of all cases. Median IOP decreased from 22 (interquartile range (IQR): 17-27) mmHg preoperatively to 14 (IQR 12-16) mmHg at 12 months postoperatively (p < 0.01). The median number of antiglaucomatous agents decreased from three to zero at latest follow-up. The Preserflo MicroShunt achieved a noticeable reduction in IOP over the course of 12 months in glaucoma patients, irrespective of disease severity or disease subtype. The frequency of postoperative adverse events and number for revision surgeries over the course of the follow-up period were low.

Early post-operative anterior segment parameters modifications induced by PreserFlo MicroShunt in primary open-angle glaucoma

PURPOSE

The aim this study is to determine anterior chamber parameters variations induced by PreserFlo MicroShunt implantation, in the early post-operative days.

METHODS

This is a prospective observational study on 48 eyes undergoing PreserFlo MicroShunt implantation alone (n = 30) or combined with phacoemulsification (n = 18). Anterior chamber depth (ACD) and volume (ACV), central corneal thickness (CCT) and total corneal astigmatism (TCA) were evaluated pre-operatively, post-operatively at day-1 and at 1 week with the Pentacam tomography.

RESULTS

Intraocular pressure decreased significantly from 20.9 ± 4.0 to 8.0 ± 2.8 mmHg (p < 0.0001) and to 10.8 ± 3.7 mmHg (p = 0.0001) at day-1 and week-1, respectively. TCA varied significantly from baseline (1.5 ± 1.2 D) to both day 1 follow up (2.7 ± 1.9 D, p = 0.0003) and week 1 follow up (2.2 ± 1.6 D, p = 0.02). Nevertheless, only K1 showed a transient flattening at day 1, while K2 value didn't show any statistical variation in the early post-operative period. CCT value rose significantly at day 1 (547 ± 49 vs. 529 ± 32 µm at baseline, p = 0.04), but then returned toward pre-operative values at week 1 (537 ± 39 µm, p = 0.57). In contrast, ACD values changed insignificantly from 3.3 ± 0.9 to 3.7 ± 1.0 mm at day 1 (p = 0.21), and then stabilized at 3.4 ± 0.9 mm (p = 0.82) at week 1 follow up. ACV changed from 150.0 ± 36.2 to 159.5 ± 42.1 mm³ at day 1 (p = 0.58), and successively to 153.9 ± 37.9 mm³ at week 1 follow up (p = 0.96). The subgroup analysis in eyes undergoing standalone PreserFlo implantation didn't show significant changes in both ACD and ACV.

CONCLUSION

PreserFlo implantation minimizes the anterior chamber modifications generated by traditional filtering surgery, inducing low and transient corneal and biometric changes only in the very early postoperative period and insignificant changes to ACD and ACV, label of its safety and minimal invasiveness.

The PreserFlo MicroShunt in the Context of Minimally Invasive Glaucoma Surgery: A Narrative Review

Recently, the quest for novel glaucoma surgical techniques and devices has been underway. Trabeculectomy remains the gold standard, but it requires the implantation of glaucoma drainage devices and frequent follow-ups, and it also carries a high risk of serious complications. The need for less invasive and safer procedures has led to the development of minimally invasive glaucoma surgery (MIGS), particularly for patients with mild-to-moderate disease. Among them, minimally invasive bleb surgery seems to be effective in classical glaucoma surgery, while maintaining MIGS benefits. The relatively new PreserFlo® MicroShunt (Santen, Osaka, Japan) is registered in Europe. It was released in 2019 for the treatment of patients with early-to-advanced open-angle glaucoma, where intraocular pressure (IOP) remains uncontrolled while on maximum tolerated medication and/or where glaucoma progression warrants surgery. This review focuses on the place of the PreserFlo MicroShunt, characterized by ab externo implantation, among MIGS procedures, discussing its advantages and disadvantages. The mechanisms of action, technical aspects, efficacy, and safety issues are summarized. The surgical technique, its efficacy, and safety profile are described, and directions for future studies are indicated. The PreserFlo MicroShunt ensures a high safety profile, minimal anatomical disruption, meaningful IOP-lowering effect, and ease of use for patients and physicians.

Early evaluation of optic nerve head morphology and choroidal thickness after PreserFlo MicroShunt implantation

PURPOSE

The aim of this study is to investigate changes in choroidal and optic nerve morphological parameters following MicroShunt PreserFlo implantation. The secondary aim is to investigate how the structural changes relate to the decrease in intraocular pressure (IOP).

METHODS

Prospective observational study on 15 eyes with glaucoma requiring MicroShunt implantation. Optical coherence tomography was used to measure macular choroidal thickness (MCT), peripapillary choroidal thickness (PCT), lamina cribrosa depth (LCD), cup depth and prelaminar tissue thickness (PLT), before and one day after surgery. Results were expressed in median and interquartile range (IQR) and correlated with IOP results.

RESULTS

The IOP decreased from a median of 25 (IQR = 11) mmHg to 8 (IQR = 2) mmHg the day after surgery. Median MCT increased after MicroShunt implantation from 252.1 (IQR = 156.4) µm to a postoperative value of 318.1 (IQR = 166.6) µm (p < 0.001), with a median increase of + 87.7 µm (+ 26.4%). PCT increased from 157.2 (IQR = 109.1) µm before surgery to 206.0 (IQR = 136.1) µm after surgery (p < 0.001). Moreover, we found a significant post-operative decrease in cup depth (median reduction of - 29.3 µm, p < 0.001) and an increase in PLT (median increase of 27.3 µm, p = 0.028). On the other side, LCD reduction 24 h after surgery didn't reach any statistical significance.

CONCLUSION

PreserFlo implantation determines retinal structural changes which appear similar to those caused by traditional filtering surgery, confirming the effectiveness of this device, meantime carrying a much smaller complications rate when compared to trabeculectomy.

Early Complications and Results of Preserflo MicroShunt in the Management of Uncontrolled Open-Angle Glaucoma: A Case Series

We analyze the surgical outcomes and early complications with their management of the Preserflo MicroShunt (Santen Pharmaceutical Co., Ltd., Osaka, Japan) at six-month follow-up. The study is conducted between March 2021 and May 2022. Best-corrected visual acuity (BCVA) logMAR, intraocular pressure (IOP), and changes in glaucoma medications are assessed. Thirty eyes of 30 patients (22 women [73.3%] and 8 men [26.7%]) are included. They are augmented with mitomycin C (MMC) 0.5 mg/mL (8 subjects) or MMC 0.2 mg/mL (22 subjects) intraoperatively. BCVA is significantly higher one day after the treatment than before the treatment (MD with 95% CI = 0.05 (<0.01; 0.30); p = 0.045) when analyzing all patients. Such dependency is not observed when analyzing only patients treated with MMC 0.2 or 0.5 mg/mL (p > 0.050 for both analyses). No other statistically significant differences are detected in the level of BCVA before and after treatment. Among the patients, overall IOP is significantly lower at each time point after treatment than before surgery (p < 0.001 for all analyses). Among patients augmented with MMC 0.2 mg/mL, the IOP level is also significantly lower at each time point after treatment than before treatment (p ≤ 0.001 for all analyses). The same differences are observed among patients with MMC = 0.5—the IOP level is significantly lower at each time point after treatment than before treatment (p < 0.050 for all analyses). Five subjects (16.7%) require anti-glaucoma medications three months after the procedure. Early complications (hypotony, choroidal effusion, keratitis, hyphema, and bleb fibrosis) are observed in 46.7% of cases. Our early results show that Preserflo MicroShunt is safe and effective for lowering IOP; however, it is not free from transient complications.

Anterior Segment-Optical Coherence Tomography Bleb Morphology Comparison in Minimally Invasive Glaucoma Surgery: XEN Gel Stent vs. PreserFlo MicroShunt

Background: The purpose of this study is to compare the morphology of six-month follow-up blebs created by a subconjunctival glaucoma surgical device (XEN45) to those created by a PreserFlo MicroShunt with a sub-Tenon insertion, utilizing AS-OCT. Methods: A retrospective study of 29 eyes who underwent XEN45 implantation and 29 eyes who underwent PreserFlo MicroShunt implantation. The patients were analyzed at 24 h, 1 week, 1 month, 3 months and 6 months. At each visit, the maturation and morphological alterations of the blebs were observed, as well as connections with the IOP. Results: In both groups, IOP showed significant reduction at all follow ups (p < 0.0001). In XEN group, the most common bleb morphology in the immediate postoperative was the subconjuntival separation type (42%) followed by the uniform type (34%), with a trend inversion at 6 month follow up (51% of uniform type). On the contrary, the most common morphology after PreserFlo was the multiple internal layer (55%), which showed a tendency to reduce over time and was substituted by the microcystic multiform, whose percentage increased over time (17% at day 1 vs. 44% at month 6). Uniform appearance was associated by the posterior episcleral fluid (PEF) lake presence. Both horizontal and vertical diameters significantly increased over time. Conclusion: XEN and PreserFlo implantation resulted in the production of diffuse blebs with different characteristics, which may influence IOP lowering capacity and bleb revisions necessity over time.