The use of intraluminal PRESERFLO stenting in avoiding early postoperative hypotony.

PURPOSE: Postoperative hypotony following PRESERFLO MicroShunt (PMS) implantation is a frequent cause of complications such as choroidal detachment and hypotony maculopathy. This study aims at evaluating the impact of intraluminal stenting of the PMS during the early postoperative period. METHODS: We retrospectively analyzed the data of 97 patients who underwent PMS implantation with intraoperative placement of a Nylon 10-0 suture as intraluminal stent (PStent) and compared the outcomes to those of an existing database of the traditional MicroShunt implantation technique (PTrad, n = 120). The primary outcome measure was the intraocular pressure (IOP) at one week postoperatively. As a secondary outcome measure, adverse hypotony, defined as an IOP ≤ 5 mmHg with significant choroidal effusion and/or anterior chamber shallowing or the presence of macular folds was also assessed. Additionally, the time to stent removal and the IOP one week after stent removal were reported. RESULTS: Preoperative median IOP was 25.0 (20.5-30.3) mmHg in PStent and 25.0 (19.3-32.0) mmHg in PTrad (p = 0.62). One week after surgery, the median IOP dropped to 10.0 (8.0-13.0) mmHg in PStent and 7.0 (5.0-9.0) in PTrad (p < 0.01). At one month, the IOP was 12.0 (10.0-14.0) mmHg in PStent and 10.0 (8.0-11.0) mmHg in PTrad (p < 0.01). After 3 months, both groups showed similar median IOP levels of 11.0 (8.0-13.5) mmHg and 10.0 (9.75-13.0) mmHg in PStent and PTrad, respectively (p = 0.66). The presence of adverse hypotony was significantly lower in PStent compared to PTrad (6.2% vs 15.8%, p < 0.05). In PStent the stent was removed after 30.0 (21.0-42.5) days. One week after stent removal the mean IOP drop was 6.1 ± 0.5 mmHg (p < 0.01). CONCLUSION: In the early follow-up period, intraluminal stenting of the PMS appears to be safe and effective in controlling the IOP while reducing early postoperative hypotony. Surgical success is not compromised by stent placement. Based on our data, it is recommended to remove the suture two to six weeks after surgery for most patients with uncomplicated postoperative clinical findings.

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.

Histopathological findings of failed blebs after microinvasive bleb surgery with the XEN Gel Stent and Preserflo MicroShunt.

PURPOSE: The success of XEN Gel Stent (XEN) and Preserflo MicroShunt (Preserflo) implantation depends mainly on the development of bleb fibrosis. This study aimed to describe the histological findings of bleb fibrosis after XEN and Preserflo surgery. METHODS: This retrospective study included patients with different types of glaucoma who underwent revision surgery after XEN or Preserflo implantation. The available clinical information and histological samples of removed fibrotic tissue were analyzed. RESULTS: Thirty-six patients were included. Revision surgery was performed at a median of 195 (range = 31-1264) days after primary surgery. The mean intraocular pressure changed from 29.1 (± 10.3) mmHg at baseline to 18.3 (± 8.7) mmHg (- 37%; p < 0.0001) and 16.2 (± 4.2) mmHg (- 45%; p < 0.0001) after 6 and 12 months, respectively. Histological analysis revealed an increase in activated fibroblasts and macrophages in all specimens and a parallel orientation of fibroblasts in a minor part of the probe in 60% of the specimens. No pronounced inflammatory reaction in the form of lymphocytic or granulocytic infiltration was observed. The comparison of specimens from uveitic glaucoma and primary open-angle glaucoma patients revealed no significant differences. CONCLUSIONS: The histological analysis of fibrotic blebs from the XEN and Preserflo implants did not show any pronounced immune or foreign-body reaction and revealed a similar histological pattern of failed blebs after trabeculectomy.

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 versus trabeculectomy: 1-year results on efficacy and safety.

PURPOSE: To compare the efficacy and safety of the PRESERFLO™ MicroShunt versus trabeculectomy in patients with primary open-angle glaucoma (POAG) after one year. PATIENTS AND METHODS: Institutional prospective interventional cohort study comparing eyes with POAG, which had received the PRESERFLO™ MicroShunt versus trabeculectomy. The MicroShunt group was matched with the trabeculectomy group for age, known duration of disease, and number and classes of intraocular pressure (IOP) lowering medications to have similar conjunctival conditions. The study is part of the Dresden Glaucoma and Treatment Study, using a uniform study design, with the same inclusion and exclusion criteria, follow-ups and standardized definitions of success and failure for both procedures. PRIMARY OUTCOME MEASURES: mean diurnal IOP (mdIOP, mean of 6 measurements), peak IOP, and IOP fluctuations. SECONDARY OUTCOME MEASURES: success rates, number of IOP lowering medications, visual acuity, visual fields, complications, surgical interventions, and adverse events. RESULTS: Sixty eyes of 60 patients, 30 in each group, were analyzed after 1-year follow-ups. Median [Q25, Q75] mdIOP (mmHg) dropped from 16.2 [13.8-21.5] to 10.5 [8.9-13.5] in the MicroShunt and from 17.6 [15.6-24.0] to 11.1 [9.5-12.3] in the trabeculectomy group, both without glaucoma medications. Reduction of mdIOP (P = .596), peak IOP (P = .702), and IOP fluctuations (P = .528) was not statistically significantly different between groups. The rate of interventions was statistically significantly higher in the trabeculectomy group, especially in the early postoperative period (P = .018). None of the patients experienced severe adverse events. CONCLUSION: Both procedures are equally effective and safe in lowering mdIOP, peak IOP and IOP fluctuations in patients with POAG, one year after surgery. CLINICAL TRIAL REGISTRATION: NCT02959242.

Effectiveness and cost-effectiveness of MicroShunt implantation versus standard trabeculectomy for open-angle glaucoma (a SIGHT study): study protocol of a multicentre randomised controlled trial.

BACKGROUND: Trabeculectomy is the "gold standard" initial surgical procedure for open-angle glaucoma worldwide. During the last decade, the introduction of less invasive procedures, including new bleb-forming surgery such as the MicroShunt, has altered the approach of glaucoma management. At present, there is insufficient evidence comparing the effectiveness between these procedures nor versus trabeculectomy. Furthermore, there is no data available on patient impact and cost-effectiveness. This study aims to address this gap in evidence and establish whether MicroShunt implantation is non-inferior compared to trabeculectomy with regard to effectiveness and whether it is cost-effective. METHODS: A multicentre, non-inferiority, randomised controlled trial (RCT) studying open-angle glaucoma with an indication for surgery will be conducted. Patients with previous ocular surgery except for phacoemulsification are excluded, as are patients with ocular comorbidity compromising the visual field or requiring a combined procedure. After informed consent is obtained, patients will be randomly allocated to the intervention, a PRESERFLO™ MicroShunt implantation, or the control group, trabeculectomy, using block randomisation (blocks of 2, 4 or 6 patients). In total, 124 patients will be randomised in a 1:1 ratio, stratified by centre. The primary endpoint will be intraocular pressure (IOP) one year after surgery. Secondary outcomes include IOP-lowering medication use, treatment failure, visual acuity, visual field progression, additional interventions, adverse events, patient-reported outcome measures (PROMs), and cost-effectiveness. Study outcomes will be measured up to 12 months postoperatively. DISCUSSION: This study protocol describes the design of a multicentre non-inferiority randomised controlled trial. To this date, cost-effectiveness studies evaluating the MicroShunt have not been undertaken. This multicentre RCT will provide more insight into whether MicroShunt implantation is non-inferior compared to standard trabeculectomy regarding postoperative IOP and whether MicroShunt implantation is cost-effective. TRIAL REGISTRATION: ClinicalTrials.gov, Identifier: NCT03931564 , Registered 30 April 2019.

Single versus Double PreserFlo MicroShunt Implantation in Glaucoma Patients: A Retrospective Cohort Study.

INTRODUCTION: The aim of this study was to describe and evaluate double PreserFlo MicroShunt implantation as a modified micro-invasive glaucoma surgery technique and to retrospectively compare the outcomes in a cohort of glaucoma patients with single or double implantation. MATERIALS AND METHODS: A retrospective data analysis of 57 glaucoma patients who consecutively underwent PreserFlo implantation was performed. Medical records were examined for patients' demographics, glaucoma type, intraocular pressure (IOP), medication, complications, and re-interventions. Two groups with single (n = 29) or double (n = 28) implantation were formed, and the outcomes were compared. In cases of two-stage double implantation (n = 17), the courses of the initial and the second implantations were compared. RESULTS: Mean preoperative IOP was significantly higher in the double compared to the single implantation group (29.4 ± 10.0 mm Hg; 21.7 ± 8.2 mm Hg; p = 0.003). Postoperatively, IOP was significantly lower in the double implantation group at various time-points (day 1, week 1, months 3 and 6; all p < 0.021). In the subgroup with two-stage procedures, mean preoperative IOP was 24.5 ± 8.5 mm Hg and 29.8 ± 10.1 mm Hg, respectively (p = 0.128). While immediately postoperatively, mean IOP lowering was clinically significant and similar following both procedures, the longer sustainable effect was observed after the second procedure (month 12: 25.5 ± 7.5 mm Hg; 12.4 ± 4.8 mm Hg; p = 0.001). No serious complications were observed. DISCUSSION/CONCLUSION: Double PreserFlo implantation appears safe and efficient for lowering IOP in glaucoma patients. Our preliminary findings suggest that double is superior to single implantation in terms of IOP lowering and the need for additional topical medication. Patients with insufficient IOP lowering following single implantation may benefit from a second implantation. Further research is warranted to evaluate double implantation as a first-line, one-stage procedure.

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.

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.

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 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.

Comparative Cost-effectiveness of Trabeculectomy versus MicroShunt in the US Medicare System.

PURPOSE: To assess the societal cost-utility of the MicroShunt compared with trabeculectomy for the surgical management of glaucoma in the US Medicare system. DESIGN: Cost-utility analysis using efficacy and safety results of a randomized controlled trial and other pivotal clinical trials. PARTICIPANTS: Markov model cohort of patients with open-angle glaucoma. METHODS: Open-angle glaucoma treatment costs and effects were analyzed with a deterministic model over a 1-year horizon using TreeAge software. Health states included the Hodapp-Parrish-Anderson glaucoma stages (mild, moderate, advanced, blind) and death. Both treatment arms received additional ocular hypotensive agents to control intraocular pressure (IOP). Treatment effect was measured as mean number of ocular hypotensive medications and reduction in IOP, which had a direct impact on transition probabilities between health states. Analyses of scenarios were performed with longer time horizons. One-way sensitivity and probabilistic sensitivity analyses were conducted to assess the impact of alternative model inputs. Both treatment arms were subject to reported complication rates, which were factored in the model. MAIN OUTCOME MEASURES: Incremental cost per quality-adjusted life-year (QALY) gained. RESULTS: At 1 year, the MicroShunt had an expected cost of US dollars (USD) 6318 compared with USD 4260 for trabeculectomy. MicroShunt patients gained 0.85 QALYs compared with 0.86 QALYs for trabeculectomy, resulting in a dominated incremental cost-utility ratio of USD 187 680. Dominance is a health economic term used to describe a treatment option that is both more costly and less effective than the alternative. The MicroShunt remained dominant in 1-way sensitivity analyses using best-case input parameters (including a device fee of USD 0). At a willingness-to-pay threshold of USD 50 000, the likelihood of the MicroShunt being cost-effective was 6.4%. Dominance continued in longer time horizons, up to 20 years. CONCLUSIONS: Trabeculectomy appears to be a dominant treatment strategy over the MicroShunt in the surgical management of glaucoma. More independent, long-term studies are required for the MicroShunt and other subconjunctival microstent devices to evaluate their use in clinical practice.

Inter-eye relationship of intraocular pressure change after unilateral trabeculectomy, filtering canaloplasty, or PreserFlo™ microshunt implantation.

PURPOSE: This study assesses short-term intraocular pressure (IOP) change in the fellow eye of glaucoma patients after mitomycin C-augmented trabeculectomy, filtering canaloplasty, or PreserFlo™ microshunt implantation in the treated eye. MATERIALS AND METHODS: Retrospective chart review of 235 glaucoma patients (235 eyes) was performed. Patients underwent initial trabeculectomy (187 patients), filtering canaloplasty (25 patients), or PreserFlo™ microshunt implantation (23 patients) in one eye, while the fellow eye was naïve to any previous glaucoma surgery. IOP was evaluated before and on the 1st and 2nd days and at 1 week after surgery. Main outcome measure was IOP change in the fellow eye. Secondary outcomes were proportion of clinically significant IOP elevation in the fellow eye and evaluation of potential risk factors associated with postoperative IOP fluctuation. RESULTS: IOP in the fellow eye at 1 week after trabeculectomy was statistically significantly lower than preoperatively (p < 0.0001), while the IOP did not change significantly in the fellow eyes in filtering canaloplasty or PreserFlo groups. The higher the preoperative IOP was in the fellow eye, the larger was the intraocular pressure-lowering effect at 1 week after trabeculectomy (p < 0.0001). A clinically significant IOP elevation was noted in 14.2%, 9.5%, and 5% of fellow eyes after trabeculectomy, filtering canaloplasty, or PreserFlo™ microshunt implantation, respectively. CONCLUSIONS: This study shows an IOP-lowering effect in the fellow eye of glaucoma patients after trabeculectomy. Significant IOP rise might occur in the fellow eye of some glaucoma patients after different types of glaucoma surgery.

PreserFlo MicroShunt® exposure: a case series.

BACKGROUND: PreserFlo® MicroShunt (PM) (also known as InnFocus® MicroShunt) is a subconjunctival stent implanted ab externo via a minimally invasive surgical procedure. The current indication is progressive, mild to moderate, open angle glaucoma uncontrolled on topical medications. According to the literature, adverse events are rare, mild and transient. CASE PRESENTATION: Two cases of stand-alone PreserFlo MicroShunt® implantation in patients with uncontrolled open-angle glaucoma are reported. Exposure occurred 7 days and 3 months respectively after implantation. These cases shared common features including preexisting blepharitis and the lack of a Tenon's flap. In both cases, removal of the device was required after several attempts at repair. CONCLUSIONS: PreserFlo MicroShunt® exposure is a potentially vision-threatening complication because of the risk of endophthalmitis. Potential risk factors include the absence of a Tenon's flap and pre-existing ocular surface inflammation. Ocular surface inflammation should be detected and treated prior to PM implantation. If a deficiency in Tenon's capsule is noted intraoperatively, close monitoring should be performed because of the higher risk of PM exposure.

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.

Ab Interno Intraluminal Stent Insertion for Prolonged Hypotony After PreserFlo MicroShunt Implantation.

This study aimed to present an effective and minimally invasive method for treating prolonged hypotony after PreserFlo MicroShunt (PMS) implantation, which can cause serious complications. A 79-year-old man with primary open-angle glaucoma of the right eye underwent ab interno intraluminal stent insertion for prolonged hypotony after PMS implantation. After making two corneal incisions at the 5 and 8 o'clock positions in the right eye, a viscoelastic material was injected into the anterior chamber. A 10-0 nylon suture was inserted into the anterior chamber through a corneal incision in the 5 o'clock position. Next, the 10-0 nylon suture was grasped and inserted into the PMS lumen as a stent with forceps, following which it was cut approximately 1 mm from the tip of the PMS using micro-iris scissors. Finally, the viscoelastic material in the anterior chamber was washed with a balanced salt solution, and self-closure of the two corneal incisions was confirmed. After ab interno intraluminal stent insertion, hypotony improved and stabilized at approximately 10 mmHg. The shallow anterior chamber, choroidal detachment, and hypotonic maculopathy improved rapidly. This novel technique demonstrated effectiveness and minimal invasiveness in treating prolonged hypotony after PMS implantation.

A short-term comparison of surgical results between an ab-externo microshunt and trabeculectomy with a main focus on postoperative corneal astigmatism.

PURPOSE: To compare surgical results between ab-externo microshunt surgery and trabeculectomy, focusing on postoperative corneal astigmatism. STUDY DESIGN: Retrospective study. METHODS: Subjects were patients with glaucoma who underwent either standalone ab-externo microshunt surgery or trabeculectomy. Data on ophthalmic examinations obtained preoperatively and 1, 3, and 5 months postoperatively were analyzed. To assess corneal astigmatism, two separate data sets measured by anterior segment optical coherence tomography and autorefractometer were evaluated. Multivariate linear mixed model analyses were conducted to identify factors associated with the astigmatism changes. RESULTS: Sixty eyes were examined: 13 eyes underwent microshunt surgery, and 47 eyes underwent trabeculectomy. The total corneal astigmatism measurements by anterior segment optical coherence tomography (AS-OCT) were: - 1.15 ± 0.85 D and - 1.17 ± 0.81 D for the microshunt and trabeculectomy groups, respectively, preoperatively. At five months postoperatively they were - 0.92 ± 0.47 D and - 1.61 ± 0.83 D, respectively (P = 0.807 for the microshunt group and P = 0.005 for the trabeculectomy group: Wilcoxon signed-rank test). AS-OCT also indicated similar results for posterior corneal astigmatism. Autorefractometry also found the total corneal astigmatism was significantly changed only in the trabeculectomy group. The linear mixed model analysis revealed that trabeculectomy (P = 0.001), older age (P = 0.004), and longer postoperative period (P = 0.015) were correlated with greater astigmatism changes. The intraocular pressures significantly decreased following both surgical treatments. CONCLUSIONS: Standalone ab-externo microshunt surgery has less effect on corneal astigmatism during a 5 month period than trabeculectomy. Both surgical procedures significantly reduced intraocular pressure.

In vivo evaluation of a nanotechnology-based microshunt for filtering glaucoma surgery.

To carry out the preclinical and histological evaluation of a novel nanotechnology-based microshunt for drainage glaucoma surgery. Twelve New Zealand White rabbits were implanted with a novel microshunt and followed up for 6 weeks. The new material composite consists of the silicone polydimethylsiloxane (PDMS) and tetrapodal Zinc Oxide (ZnO-T) nano-/microparticles. The microshunts were inserted ab externo to connect the subconjunctival space with the anterior chamber. Animals were euthanized after 2 and 6 weeks for histological evaluation. Ocular health and implant position were assessed at postoperative days 1, 3, 7 and twice a week thereafter by slit lamp biomicroscopy. Intraocular pressure (IOP) was measured using rebound tonometry. A good tolerability was observed in both short- and medium-term follow-up. Intraocular pressure was reduced following surgery but increased to preoperative levels after 2 weeks. No clinical or histological signs of inflammatory or toxic reactions were seen; the fibrotic encapsulation was barely noticeable after two weeks and very mild after six weeks. The new material composite PDMS/ZnO-T is well tolerated and the associated foreign body fibrotic reaction quite mild. The new microshunt reduces the IOP for 2 weeks. Further research will elucidate a tube-like shape to improve and prolong outflow performance and longer follow-up to exclude medium-term adverse effects.

PRESERFLO™ Microshunt: 1-Year Results of a 25-Gauge vs. 27-Gauge Needle Tract.

Background: The purpose of this study was to evaluate the effectiveness and safety of the PreserFlo™ microshunt (PMS) using a 25-Gauge vs. 27-Gauge needle tract. Methods: This is a prospective postoperative examination of 60 glaucoma eyes that received a PMS. The main outcome measures were intraocular pressure (IOP), glaucoma drug score (GDS), Kaplan-Meier success rates, complications, and secondary intervention rates. Two subgroups were formed for data comparison: 27-Gauge (27G), and 25-Gauge (25G). Success was defined as IOP < 18 mmHg together with ≥20% IOP reduction with medication allowed (qualified success = QS18) or not (full success = FS18). Results: IOP and GDS were reduced from baseline to the 1-year study visit as follows: All eyes from 23.4 ± 8.6 mmHg (3.1 ± 0.9) to 15.1 ± 5.9 mmHg (0.8 ± 1.1); 25G from 24.2 ± 7.3 mmHg (3.0 ± 0.8) to 12.7 ± 2.7 mmHg (0.5 ± 0.8); and 27G from 23.1 ± 9.2 mmHg (3.1 ± 1.0) to 16.2 ± 6.7 mmHg (0.9 ± 1.2). IOP at one year was lower in the 25G group compared to the 27G group (p = 0.035). Bleb needling was required in eight (13.3%) eyes and open bleb revisions in three (5.0%). Transient hypotony occurred in 21% and choroidal effusion in 8% of all eyes. Choroidal effusions were more frequent in the 25G group (21%) compared to the 27G group (2%, p = 0.031). One-year success rates were significantly higher in the 25G group compared to the 27G group for both QS18 (25G: 67.9% vs. 27G: 35.7%, p = 0.002) and FS18 (25G: 63.6% vs. 27G: 29.2%, p = 0.007). Conclusions: The PreserFlo microshunt is an effective and safe glaucoma surgery with a low rate of bleb revisions or needlings. We show that the 25G needle tract might be more efficient for IOP control at the cost of increased IOP-related complications compared to 27G.

Bleb vessel density as a predictive factor for surgical revisions after Preserflo Microshunt implantation.

PURPOSE: Bleb failure is a common complication after glaucoma filtration surgery. Different bleb classification schemes incorporating filtration bleb vascularization have been proposed, but the reported correlation with intraocular pressure (IOP) has been variable, possibly because of subjective vascularization grading. The purpose of the present study was to evaluate bleb vascularization after Preserflo Microshunt (PM) implantation using anterior segment OCT-angiography (AS-OCTA) as a biomarker for bleb failure. METHODS: Twenty-three eyes of twenty-three patients underwent PM implantation. Up to 12 months after surgery PM scleral passage-centred AS-OCTA measurements (PLEX Elite 9000) for bleb-vessel density (BVD) determination were performed and IOP as well as necessity for surgical revisions (needling and open revision) were documented. After multi-step image analysis (region of interest definition, artefact removal, binarization, BVD calculation), the predictive value of early postoperative BVD for surgical revisions was assessed using logistic regression modelling. RESULTS: Baseline IOP (23.57 ± 7.75 mmHg) decreased significantly to 8.30 ± 2.12, 9.17 ± 2.33 and 11.70 ± 4.40 mmHg after 1, 2 and 4 week(s), and 13.48 ± 5.83, 11.87 ± 4.49, 12.30 ± 6.65, 11.87 ± 3.11 and 13.05 ± 4.12 mmHg after 2, 3, 6, 9 and 12 month(s), respectively (p < 0.001). Nine patients (39%) needed surgical revisions after a median time of 2 months. Bleb vessel densities at 2 and 4 weeks were significantly associated with future surgical revisions upon logistic regression analysis (2 W/4 W likelihood-ratio test p-value: 0.0244/0.0098; 2 W/4 W area under the receiver operating characteristics curve: 0.796/0.909). CONCLUSION: Filtration bleb vessel density can be determined using AS-OCTA in the early postoperative period and is predictive for bleb failure after PM implantation.