Treatment Outcomes Using the PAUL Glaucoma Implant to Control Intraocular Pressure in Eyes with Refractory Glaucoma

Two-Year Clinical Outcomes of the PAUL Glaucoma Implant in White Patients With Refractory Glaucoma

PRCIS

This prospectively collected case series of 56 eyes having PAUL glaucoma implant (PGI) surgery is the first to demonstrate its medium-term safety and effectiveness in what is essentially an exclusively Caucasian population.

BACKGROUND

To report 2-year outcomes from a single-center cohort undergoing PGI surgery.

METHODS

Prospectively collected data on patients undergoing PGI surgery at the University Eye Hospital Bonn, Germany, from April 2021 to September 2021.

RESULTS

Of 53 patients, 56 eyes were included. Complete and qualified success rates (95% CI) were 52% (37-66) and 89% (80-96) for criterion A ( intraocular pressure [IOP]≤21 mm Hg), 48% (36-61) and 79% (67-88) for criterion B (IOP≤18 mm Hg), 45% (32-57) and 64% (52-77%) for criterion C (IOP≤15 mm Hg) and 27% (16-40) and 38% (25-50) for criterion D (IOP≤12 mm Hg), respectively. Mean IOP decreased from 25.43 mm Hg (7-48 mm Hg) to 11.25 mm Hg (3-24 mm Hg) (reduction of 50%) after 24 months with a reduction of IOP-lowering agents from 3.50 (1-5) to 0.46 (0-3). One eye needed an injection of viscoelastic due to significant hypotony with AC shallowing; 3 eyes received a Descemet membrane endothelial keratoplasty because of persistent corneal decompensation; 9 eyes developed tube exposure which required conjunctival revision with additional pericardial patch graft, with 5 of these eyes eventually needing tube explantation. An intraluminal prolene stent was removed in 24 eyes (42.9%) after a mean time period of 5.67 months (2-15 m). Mean IOP before removal was 21.4 mm Hg (12-40 mm Hg) and decreased to 11.15 mm Hg (6-20 mm Hg).

CONCLUSIONS

PGI surgery is an effective procedure for reducing IOP and pressure-lowering therapy. The use of an intraluminal prolene stent impedes hypotony in the early postoperative phase and enables further noninvasive IOP lowering during the postoperative course.

Efficacy and safety of the paul glaucoma implant in the treatment of refractory primary congenital glaucoma

PURPOSE

To evaluate the safety and efficacy of the PAUL Glaucoma Implant (PGI) for managing refractory primary congenital glaucoma (PCG) over a one-year period.

STUDY DESIGN

Retrospective.

METHODS

A study was conducted using the medical records of thirty eyes of 17 patients who underwent PGI surgery for the treatment of refractory PCG. Primary outcome measures included failure criteria such as intraocular pressure (IOP) > 21 mm Hg, < 20% IOP reduction, necessity for further glaucoma intervention, implant removal, or loss of vision. Secondary outcomes focused on mean IOP, average number of glaucoma medications, best corrected visual acuity (logMAR), and incidence of complications.

RESULTS

The mean preoperative IOP of 38.8 ± 9.2 mmHg significantly decreased to 16.1 ± 3.3 mmHg at 12 months postoperatively (p < 0.001). The average number of glaucoma medications reduced from 3.6 ± 0.5 preoperatively to 0.9 ± 1.2 at 12 months post-op. Visual acuity remained stable in 24 eyes, decreased in 4, and increased in 2. Early postoperative complications occurred in 13.3% of patients, but no late complications were reported. The cumulative success rate was 86.6%.

CONCLUSION

The PGI appears to be a safe and effective option for managing refractory primary congenital glaucoma, demonstrating significant IOP reduction and decreased dependence on glaucoma medications over a one-year period, with a high success rate and manageable complication profile.

Treatment Outcomes Comparing the Paul and Baerveldt Glaucoma Implants After One Year of Follow-Up

PRCIS

In reducing intraocular pressure (IOP), Paul (PGI) and Baerveldt (BGI) glaucoma implants are safe and effective in patients with glaucoma.

OBJECTIVE

To compare efficacy and safety profiles of the PGI and BGI in the treatment of medically uncontrolled glaucoma at 1 year of follow-up.

METHODS

Retrospective analysis of patients implanted with a PGI or BGI with a minimum of 12 months follow-up. The primary outcome was surgical success defined as IOP ≥6 and ≤18 mm Hg and at least 20% IOP reduction from baseline. Secondary outcomes included IOP measurements, number of medications, and complications.

RESULTS

Twenty-three patients implanted with PGI and 27 with BGI were included. At last visit (12 mo), mean IOP had decreased from 23.7 ± 6.9 to 0.1 ± 2.9 mm Hg in the PGI group versus 26 ± 7.3 to 10.4 ± 4.9 mm Hg with the BGI ( P < 0.001 for both comparisons). Overall qualified success rates were similar between groups (PGI 91% vs BGI 89%, P = 0.784). IOP was significantly lower in the PGI at week 1 and month 1 of follow-up versus the BGI (13.6 ± 6.1 vs 20.1 ± 7.4; 14.6±3.8 vs 21.2 ± 5.8 mm Hg; P < 0.002 for both) with a lower number of medications (1.57 ± 1.47 vs 2.52 ± 1.16 at mo 1, P = 0.015). Most complications were minor and similar in both groups.

CONCLUSION

Both PGI and BGI are safe and effective in reducing IOP in patients with glaucoma, with similar success rates.

Three-Year Outcomes of the Paul Glaucoma Implant for Treatment of Glaucoma

PRCIS

In our case series, the 3-year failure for Paul Glaucoma Implant (PGI) implantation was 14.6%. At 3 years postoperatively, there was a significant reduction in mean intraocular pressure (IOP) and the number of glaucoma medications used.

OBJECTIVE

To determine the 3-year efficacy and safety of the PGI, a novel glaucoma tube shunt in patients with glaucoma.

METHODS

Retrospective review of all patients who had undergone PGI implantation in a single tertiary institution in Singapore between May 1, 2017 and January 1, 2022. Data were extracted from electronic health records (Computerized Patient Support System 2 and Epic). The primary outcome measure was failure, defined as IOP >18 mm Hg or <6 mm Hg on 2 consecutive visits after 3 months, reoperation for IOP-related indication, explantation of implant, or loss of light perception vision. Complete success was defined as the absence of failure without medications at 36 months, and qualified success similarly, but with medications. Postoperative mean IOP, mean number of IOP-lowering medications used, and visual acuity were also assessed.

RESULTS

Forty-eight eyes in 48 patients were identified. Thirty-one patients (64.6%) had primary open angle and angle closure glaucoma, and 18 (37.5%) had previous existing tube implants or trabeculectomy. At 3 years postoperatively, 7 cases (14.6%) fulfilled the criteria for failure and 36 (75%) met the criteria for complete success. The mean IOP at 36 months was 14.9 ± 4.11 mm Hg, from the mean preoperative IOP of 20.6 ± 6.13 mm Hg ( P < 0.001). The mean number of IOP-lowering medications used was reduced from 3.13 ± 0.959 preoperatively to 0.167 ± 0.476 at 36 months ( P < 0.001). The most common postoperative complication was hypotony (n = 17, 35.4%), of which the majority were self-limiting, followed by hyphema (n = 5, 10.4%) and tube exposure (n = 4, 8.3%).

CONCLUSION

The PGI demonstrated sustained IOP reduction and a reduction of medication burden at 3 years postoperatively.

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?

Microfluidics in the eye: a review of glaucoma implants from an engineering perspective

Glaucoma is a progressive optic neuropathy in the eye, which is a leading cause of irreversible blindness worldwide and currently affects over 70 million individuals. Clinically, intraocular pressure (IOP) reduction is the only proven treatment to halt the progression of glaucoma. Microfluidic devices such as glaucoma drainage devices (GDDs) and minimally invasive glaucoma surgery (MIGS) devices are routinely used by ophthalmologists to manage elevated IOP, by creating an artificial pathway for the over-accumulated aqueous humor (AH) in a glaucomatous eye, when the natural pathways are severely blocked. Herein, a detailed modelling and analysis of both the natural microfluidic pathways of the AH in the eye and artificial microfluidic pathways formed additionally by the various glaucoma implants are conducted to provide an insight into the causes of the IOP abnormality and the improvement schemes of current implant designs. The mechanisms of representative glaucoma implants have been critically reviewed from the perspective of microfluidics, and we have categorized the current implants into four groups according to the targeted drainage sites of the AH, namely Schlemm's canal, suprachoroidal space, subconjunctival space, and ocular surface. In addition, we propose to divide the development and evolution of glaucoma implant designs into three technological waves, which include microtube (1st), microvalve (2nd) and microsystem (3rd). With the emerging trends of minimal invasiveness and artificial intelligence in the development of medical implants, we envision that a comprehensive glaucoma treatment microsystem is on the horizon, which is featured with active and wireless control of IOP, real-time continuous monitoring of IOP and aqueous rate, etc. The current review could potentially cast light on the unmatched needs, challenges, and future directions of the microfluidic structural and functional designs of glaucoma implants, which would enable an enhanced safety profile, reduced complications, increased efficacy of lowering IOP and reduced IOP fluctuations, closed-loop and on-demand control of IOP, etc.

Bleb morphology of glaucoma drainage devices on magnetic resonance imaging

PURPOSE

To evaluate bleb morphology features of different glaucoma drainage devices (GDD) using magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Prospective cohort study of GDD and bleb morphology in consecutive glaucoma patients implanted with Ahmed Glaucoma Valve (AGV), Paul Glaucoma Implant (PGI), Baerveldt Glaucoma Implant (BGI) and Ahmed ClearPath (ACP) devices. Thirty-six eyes from 30 consecutive patients underwent standardized GDD implantation followed by MRI at least 1 month after surgery. Main outcomes included bleb volume and endplate position relative to the optic nerve. Secondary outcomes included intraocular pressure (IOP), medication and surgical complications during a 12-month follow-up.

RESULTS

Seven eyes were implanted with the AGV (19%), 5 with BGI (14%), 16 with PGI (44%) and 8 with ACP (22%). MRI scans were obtained 85 ± 66 days after surgery. Mean total bleb volume was 563 ± 390 mm3 . This bleb volume was inversely correlated with early post-operative IOP (day 7; rs  = -0.3326, p = 0.0475) but positively correlated with IOP at 12 months (rs  = 0.3592, p = 0.0341). No significant difference in total bleb volume was found between GDD types (p = 0.1223). A double-layered bleb was observed in 34 eyes (94%). The inferior bleb volume was significantly larger in PGI devices versus other GDD types (380 ± 205 vs. 193 ± 161 mm3 ; p = 0.0043). Distance from the endplate to the optic nerve was 9.5 ± 4.0 mm, similar across GDDs (p = 0.2519).

CONCLUSIONS

Double-layered blebs are a common finding with GDDs. Bleb volume showed different correlations with IOP at distinct timepoints and the PGI device formed larger blebs. A standardized GDD implantation technique ensures a safe distance from the GDD endplate to the optic nerve.

Glaucoma Drainage Device Implantation, Outcomes, and Complications

Glaucoma drainage device (GDD) surgery has gained popularity as a treatment strategy for patients with medically uncontrolled glaucoma. Glaucoma is the leading cause of irreversible blindness in the world and continues to be a major public health issue. While our understanding of glaucoma continues to evolve, the primary treatment for glaucoma continues to be intraocular pressure (IOP) control. When medical treatment fails, glaucoma surgery is considered. GDD implantation is one of the most commonly performed incisional glaucoma surgeries. GDD was originally designed for patients with secondary glaucoma and/or patients who are at an increased risk of failure after trabeculectomy. More recently, its application has been extended to primary glaucoma as the first choice of incisional surgery. This manuscript summarizes recent GDD types, implantation, clinical outcome and complications.

[Münster standard: modified Paul® implantation in a condition following Preserflo® MicroShunt implantation. Video article]

OBJECTIVE OF SURGERY

The aim of this surgical technique is the modified placement of a Paul® implant (Fa. Advanced Ophthalmic Innovations, Singapur) in eyes after failure of Preserflo® MicroShunt (Fa. Santen, Osaka, Japan) implantation for the best possible adjustment of the intraocular pressure.

INDICATIONS

The technique presented here is intended for patients suffering from more complex glaucomas, which were unsuccessfully previously treated with a Preserflo® Microshunt (Santen Inc.).

SURGICAL TECHNIQUE

The special feature of the Münster standard is the choice of the surgical field and the waiver of a further tunnel placement. The patients receive a Paul® implant in the same quadrant as the previously inserted Preserflo® MicroShunt implant (superior temporal). The latter is explanted after preparation of the conjunctiva and priming of the Paul® implant with a Prolene 6.0 suture and fixation of the plate. In order to carry out the implantation of the Paul® tube through the existing 25-gauge tunnel, the latter is dilated laterally with an iris spatula under positioning of the anterior chamber. A surgical video, which is available online, shows the surgical technique in detail. ADVANTAGES OF THE MüNSTER STANDARD: The superior temporal surgical access promises easier handling. The fact that there is no need for a new tunnel effectively saves surgery time and is expected to reduce endothelial cell loss as only one tube remains in place in comparison to two anterior chamber tubes.

Recent Advancements in Glaucoma Surgery-A Review

Surgery has long been an important treatment for limiting optic nerve damage and minimising visual loss in patients with glaucoma. Numerous improvements, modifications, and innovations in glaucoma surgery over recent decades have improved surgical safety, and have led to earlier and more frequent surgical intervention in glaucoma patients at risk of vision loss. This review summarises the latest advancements in trabeculectomy surgery, glaucoma drainage device (GDD) implantation, and minimally invasive glaucoma surgery (MIGS). A comprehensive search of MEDLINE, EMBASE, and CENTRAL databases, alongside subsequent hand searches-limited to the past 10 years for trabeculectomy and GDDs, and the past 5 years for MIGS-yielded 2283 results, 58 of which were included in the final review (8 trabeculectomy, 27 GDD, and 23 MIGS). Advancements in trabeculectomy are described in terms of adjunctive incisions, Tenon's layer management, and novel suturing techniques. Advancements in GDD implantation pertain to modifications of surgical techniques and devices, novel methods to deal with postoperative complications and surgical failure, and the invention of new GDDs. Finally, the popularity of MIGS has recently promoted modifications to current surgical techniques and the development of novel MIGS devices.

Clinical outcomes of the PAUL® glaucoma implant: One-year results

BACKGROUND

To report one-year outcomes from a single-centre cohort undergoing PAUL® Glaucoma Implant (PGI) surgery.

METHODS

Retrospective review of patients undergoing PGI surgery at the University Eye Hospital Bonn, Germany, from April 2021 to September 2021.

RESULTS

Forty-five eyes of 41 patients were included. Qualified and complete success rates (95% CI) were 95.6% (88.9%-100%) and 73.3% (60%-86.7%) for Criterion A (IOP ≤ 21 mmHg), 84.4% (73.3%-93.3%) and 74.4% (51.1%-80.0%) for Criterion B (IOP ≤ 18 mmHg), 62.2% (48.9%-75.6%) and 46.7% (31.2%-62.2%) for Criterion C (IOP ≤ 15 mmHg) and 26.7% (13.3%-40.0%) and 22.2% (11.1%-33.3%) for Criterion D (IOP ≤ 12 mmHg), respectively. Mean IOP decreased from 26.1 mmHg (7-48 mmHg) to 12.0 mmHg (3-24 mmHg) (reduction of 48.83%) after 12 months with a reduction of IOP-lowering agents from 0.5 (0-3). One eye (2.2%) needed an injection of viscoelastic due to significant hypotony with AC shallowing, and four eyes (8.9%) developed choroidal detachments due to hypotony which resolved without further interventions after 6 weeks. Three patients (6.7%) developed tube exposure which required conjunctival revision with an additional pericardial patch graft. An intraluminal prolene stent was removed in 19 eyes (42.2%) after a mean time period of 8.4 months (2-12 m). Mean IOP before the removal was 21.9 mmHg (12-38 mmHg) and decreased to 11.3 mmHg (6-16 mmHg).

CONCLUSIONS

PGI surgery is an effective procedure for reducing IOP and pressure-lowering therapy. An intraluminal prolene stent impedes hypotony in the early postoperative phase and enables further IOP lowering without additional interventions during the postoperative course.

The PAUL® glaucoma implant: 1-year results of a novel glaucoma drainage device in a paediatric cohort

PURPOSE

The PAUL® glaucoma implant (PGI) is a novel glaucoma drainage device, which has not been previously reported in paediatric glaucoma management. This study aims to evaluate the safety and effectiveness of the PGI in a paediatric cohort.

METHODS

A retrospective evaluation of 25 cases of paediatric PGI surgery (age 8 months to 16 years) was performed at Manchester Royal Eye Hospital between September 2019 and July 2020. Primary outcome measures included failure (intraocular pressure (IOP) > 21 mmHg or < 20% reduction of IOP, removal of the implant, further glaucoma intervention or visual loss. Secondary outcomes included mean IOP, mean number of medications, logMAR visual acuity and complications.

RESULTS

Eleven eyes (48%) had a complete success and achieved an unmedicated IOP < 21 mmHg, and 21 eyes (84%) had a qualified success (with or without medications). Four failures were observed, 2 due to hypotony and 2 underwent further surgery (gonioscopy-assisted transluminal trabeculotomy). The mean preop IOP was 30.9 ± 5.9 mmHg (n = 25), falling to 13.5 ± 6.8 mmHg at 1 month, 17.9 ± 7.2 mmHg at 3 months, 13.4 ± 5.1 mmHg at 6 months, 13.2 ± 4.9 mmHg at 12 months and 11.8 ± 4.6 mmHg at 24 months. The mean change in IOP from the preoperative visit to the last visit was a reduction of 19.1 ± 7.7 mmHg. A significant reduction in the number of medications and IOP was demonstrated after PGI (p < 0.0001). Nine patients required removal of the intraluminal Prolene stent from the PGI for further pressure lowering.

CONCLUSION

The one- to two-year results demonstrate paediatric PGI has high qualified success rates and effectively reduces IOP and the need for glaucoma medical therapy.

Early Experience with the Paul Glaucoma Implant in Childhood Glaucoma: A Case Series

Purpose

The Paul glaucoma implant (PGI, Advanced Ophthalmic Innovations, Singapore, Republic of Singapore) is a recently developed novel non-valved glaucoma drainage device (GDD) designed to effectively reduce the intraocular pressure (IOP) in glaucoma patients with a theoretically reduced risk of postoperative complications such as hypotony, endothelial cell loss, strabismus, and diplopia. Limited literature has evaluated its use in adult glaucoma; however, its use in pediatric glaucoma has not been reported to date. We present our early experience with PGI in refractory childhood glaucoma.

Patients and Methods

This study was retrospective single-surgeon case series in a single tertiary center.

Results

Three eyes of 3 patients with childhood glaucoma were enrolled in the study. During nine months of follow-up, postoperative IOP and number of glaucoma medications were significantly lower than preoperative values in all the enrolled patients. None of the patients developed postoperative complications including postoperative hypotony, choroidal detachment, endophthalmitis, or corneal decompensation.

Conclusion

PGI is an efficient and relatively safe surgical treatment option in patients with refractory childhood glaucoma. Further studies with larger number of participants and longer follow-up period are required to confirm our encouraging results.

[Comparison of glaucoma drainage implants]

Glaucoma drainage devices (tubes, GDI or GDD) are nowadays an important surgical option in the treatment of refractory glaucoma. They are frequently used in cases where previous glaucoma surgery has failed or in patients with a history of conjunctival scarring where other procedures are contraindicated or simply not possible. This article looks at the evolution of glaucoma drainage implants from the very beginning to the multiple designs, experiences and research studies that have made tubes an essential part of the armamentarium of modern glaucoma surgeons. The article describes the first concepts and then proceeds to the first commercialized devices which led to the widespread use of tubes such as Molteno®, Baerveldt® and Ahmed®. Finally, it looks at the innovations that have been carried out, particularly over the last decade with the advent of new tubes, such as Paul®, eyeWatch® and Ahmed ClearPath®. The factors associated with the success and failure of GDD surgery, including the indications, are different from those for trabeculectomy and increasing experience and larger amounts of data have helped glaucoma surgeons to become more comfortable with selecting the most appropriate procedure for the individual patients.

New glaucoma drainage implants available to glaucoma surgeons

PURPOSE OF REVIEW

Glaucoma drainage device (GDD) implantation surgery is commonly performed by glaucoma specialists to treat complex and refractory glaucomas. Relative safety and efficacy data from randomized controlled trials conducted in the last two decades have sparked the interest in GDDs as possible surgical options earlier in the course of the disease than has traditionally been practiced. However, until recently, advances in the design and techniques of GDD surgery have fallen short of this increasing interest.

RECENT FINDINGS

Most recently, new GDDs that possess novel design features have become available to glaucoma specialists. Two of these new devices are the Ahmed ClearPath and the Paul glaucoma implant. These devices have demonstrated promising outcomes that are comparable to those of traditional implants. Additionally, given their unique respective features, these devices may streamline surgical technique due to ease of insertion and afford better safety and efficacy outcomes in certain patients.

SUMMARY

The recent introduction of new GDDs has been long awaited by glaucoma surgeons. Although early results are promising, long-term data and comparison of outcomes to those of traditional filtering surgery and commonly implanted devices are needed before these devices can be the new standard of care in glaucoma tube shunt surgery.

Advances in Glaucoma Surgery

Glaucoma is one of the leading causes of irreversible sight loss worldwide, with a prevalence of 64 [...].

[First clinical results with the PAUL® Glaucoma Implant at the University Eye Hospital Bonn]

BACKGROUND

Glaucoma drainage devices (GDD) are an invasive procedure for the treatment of glaucoma. The PAUL® Glaucoma Implant (PGI) has been developed as a new, innovative therapeutic procedure. The PGI differs from previous GDD with regard to the smaller size of the drainage tube.

OBJECTIVE

This study analyses 6‑months results of the PGI in terms of effectiveness and safety.

METHODS

A database of patients treated with the PGI at the University Eye Hospital Bonn was created and continuously updated based on follow-up controls. Statistical analysis was performed using SPSS Statistics for Windows (IBM Corp., Armonk, NY, USA).

RESULTS

A total of 53 eyes of the first 51 consecutive patients treated with the PGI were included in this study. Mean intraocular pressure was 26.62 mmHg (7-48 mmHg) preoperatively and reduced to 12.20 mmHg (3-22 mmHg) after 6 months. Local pressure-lowering therapy was reduced from 3.37 agents preoperatively to 0.30 agents after 6 months. The complication rate was low; only 3 patients (5.8%) had persistent hypotony. In 16 patients, the intraluminal prolene stent was removed in the postoperative course after an average of 2.9 months. Thereafter, these patients experienced a reduction of intraocular pressure from 22.21 to 11.07 mmHg.

CONCLUSION

The PAUL® Glaucoma Implant is a safe treatment modality that can successfully reduce intraocular pressure to a low level and reduce pressure-lowering local therapy. It has a low complication rate, particularly regarding postoperative hypotony.

Effect of COVID-19 pandemic on glaucoma surgical practices in the UK

BACKGROUND/AIM

The aim of the study was to examine the effect of the COVID-19 pandemic on glaucoma surgical practices within the UK.

METHODS

A cross-sectional online survey was distributed to all consultant glaucoma specialists who are on the UK and Eire Glaucoma Society contact list. Participants were asked specific questions regarding preferences in glaucoma surgical practices and whether these had changed subsequent to the onset of the COVID-19 pandemic.

RESULTS

Trabeculectomy was the procedure of choice for 61 (87%) glaucoma specialists. A total of 51 (73%) respondents reported performing minimally invasive glaucoma surgery (MIGS) procedures before the COVID-19 pandemic. The most commonly performed MIGS procedure was the iStent inject (51%), followed by XEN 45 (36%) and Preserflo (17%). Forty-three (61%) respondents reported modifying their glaucoma surgery practice subsequent to the onset of the COVID-19 pandemic. Of the glaucoma specialists who modified their surgical practices, 21 (43%) specifically reduced the number of trabeculectomies performed. In combination, diode laser (both micropulse and conventional trans-scleral cyclodiode) was the most common alternative procedure. Glaucoma drainage devices, deep sclerectomy and Preserflo were also commonly chosen alternatives.

CONCLUSION

Although trabeculectomy remains the most commonly performed established glaucoma surgery, it is being performed with reduced frequency during the COVID-19 pandemic due to the number of postoperative visits and procedures required. Alternatives such as conventional and micropulse diode laser, glaucoma drainage devices, deep sclerectomy and Preserflo appear to be the favoured alternative procedures.

Efficacy and Safety of the Preserflo Microshunt With Mitomycin C for the Treatment of Open Angle Glaucoma

PRCIS

The Preserflo Microshunt (PSM) is a safe and effective glaucoma microfiltering implant that significantly reduces the intraocular pressure (IOP), either alone or in combination with phacoemulsification, during the first year after surgery.

PURPOSE

The purpose of this study was to assess the safety and efficacy of the PSM for the treatment of open angle glaucoma with 0.2 mg/mL mitomycin C, either alone or in combination with cataract surgery.

METHODS

A retrospective, open-label study of 64 eyes with primary open angle glaucoma that underwent PSM implantation and were followed up for at least 9 months. Success was defined as IOP 6-17 mm Hg and a reduction of at least 20%, complete without hypotensive medication, and qualified with medication. Safety was assessed by the incidence of adverse events. Secondary endpoints included mean hypotensive medications, visual acuity, and incidence of needling and surgical revision.

RESULTS

A total of 51 eyes underwent PSM alone and 13 underwent PSM+phacoemulsification. In the overall population of the study, the mean IOP was significantly reduced from 22.03±0.7 mm Hg at baseline to 12.7±0.4 mm Hg at the final visit, P <0.0001 (mean follow-up: 11±1.4 mo). The IOP was significantly reduced in both groups ( P <0.0001). Ocular hypotensive medication was reduced significantly from 2.7±0.7 to 0.2±0.5 ( P <0.0001). No significant differences were found in IOP-lowering medication between groups (PSM alone, 0.2±0.08; PSM+phacoemulsification, 0.1±0.1; P =0.2). At the final visit, 70.3% were considered as complete success and 12.5% as qualified success. The most common adverse event was clinical hypotony (7.8%) followed by hyphema (4.7%), and anterior chamber reformation (1.6%). Overall, 1.6% required needling and 15.6% surgical revision to restore the flow.

CONCLUSION

Glaucoma surgery with the PSM and mitomycin C was efficacious and safe in the short term, either alone or in combination with cataract surgery, and may be considered a surgical option for lowering IOP in primary open angle glaucoma.

Two-Year Outcomes of the Paul Glaucoma Implant for Treatment of Glaucoma

PURPOSE

To determine 2-year efficacy of the PAUL Glaucoma Implant (PGI), a novel glaucoma tube shunt in patients with advanced glaucoma.

PARTICIPANTS

Patients with glaucoma refractory to maximum medical therapy or previous failed glaucoma surgery.

METHODS

Retrospective review of all patients who had underwent PGI implantation in a single tertiary institution between May 1, 2017 and March 30, 2021.

MAIN OUTCOME MEASURES

Primary outcome measure was failure defined as intraocular pressure (IOP) >18 mm Hg or <6 mm Hg on 2 consecutive visits after 3 months, reoperation for IOP-related indication, explantation of implant or loss of light perception vision. Complete success was defined as unmedicated IOP ≤18 mm Hg or ≥6 mm Hg in the absence of failure.

RESULTS

Forty-five eyes in 45 patients were identified, with mean follow-up duration of 24.9±2.0 months. Thirty patients (66.7%) had primary glaucoma and 11 (24.4%) with previous glaucoma surgery. At 2 years following surgery, 8 eyes (17.8%) fulfilled the failure criteria with 32 eyes (71.1%) achieving complete success. Compared with mean medicated preoperative IOP (19.8±6.3 mm Hg), postoperative IOP at 24 months was 13.9±3.7 (P<0.01). Mean number of medications decreased from 3.2±0.8 preoperatively to 0.29±0.65 at 24 months (P<0.01). Significant complications included self-limiting shallow anterior chamber (n=10; 22.2%), hypotony requiring intervention (n=4; 8.9%) and tube occlusion (n=4; 8.9%).

CONCLUSIONS

The PGI was able to achieve sustained IOP reduction with reduction of medications at 2 years postsurgery in patients with advanced glaucoma.

One-Year Efficacy and Safety of the PAUL Glaucoma Implant Using a Standardized Surgical Protocol

PRCIS

The PAUL Glaucoma Implant is an effective intraocular pressure (IOP)-lowering device with an acceptable safety profile. Its design as a nonvalved device with a small tube diameter using a vicryl ligation suture around the tube that is posteriorly reabsorbed instead of an ab luminal stent makes it an option in cases selected for glaucoma drainage device implantation.

PURPOSE

The aim was to determine the 1-year efficacy and safety of PAUL Glaucoma Implant using a uniform, standardized surgical procedure.

MATERIALS AND METHODS

Retrospective, cohort study. Patient charts were screened between December 2018 and January 2020, with inclusion requiring a minimum follow-up of 12 months. Primary outcome was IOP-lowering at 12 months, with surgical success defined as ≤18 mm Hg and at least 30% reduction and higher than 5 mm Hg. Absolute success was achieved if no IOP-lowering medication was needed and qualified success if otherwise. Safety outcomes were also analyzed. A standardized protocol was followed in all cases, which included mitomycin C application and 1 vicryl ligation of the tube.

RESULTS

A total of 24 eyes from 21 patients fulfilled inclusion criteria. Median patient age at time of surgery was 42 years (range: 1 to 76 y). IOP decreased from 31.4 (10.0) mm Hg in preoperative period to 12.5 (4.3) mm Hg in the last follow-up (P<0.001). Qualified success criteria were fulfilled by 75% of cases, while absolute success was 33%. The mean number of IOP-lowering drugs used before surgery was 3.0 and 0.9 at the 12-month visit (P<0.001). No postoperative hypotony requiring intervention was recorded.

CONCLUSIONS

PAUL Glaucoma Implant appears to be a safe and effective glaucoma drainage implant for the treatment of moderate and advanced glaucoma.

Conventional glaucoma implants and the new MIGS devices: a comprehensive review of current options and future directions

Glaucoma is a progressive optic neuropathy that is the second leading cause of preventable blindness worldwide, after cataract formation. A rise in the intraocular pressure (IOP) is considered to be a major risk factor for glaucoma and is associated with an abnormal increase of resistance to aqueous humour outflow from the anterior chamber. Glaucoma drainage devices have been developed to provide an alternative pathway through which aqueous humour can effectively exit the anterior chamber, thereby reducing IOP. These devices include the traditional aqueous shunts with tube-plate design, as well as more recent implants, such as the trabeculectomy-modifying EX-PRESS^® implant and the new minimally invasive glaucoma surgery (MIGS) devices. In this review, we will describe each implant in detail, focusing on their efficacy in reducing IOP and safety profile. Additionally, a critical and evidence-based comparison between these implants will be provided. Finally, we will propose potential developments that may help to improve the performance of current devices.

Evaluation of the Ultrastructural and In Vitro Flow Properties of the PRESERFLO MicroShunt

Purpose

To measure the in vitro flow properties of the PRESERFLO implant for comparison with the theoretical resistance to flow.

Methods

The PRESERFLO was designed to control the flow of aqueous humor according to the Hagen-Poiseuille (HP) equation. Scanning electron microscopy (SEM) was performed to analyze the ultrastructure, and flow measurements were carried out using a gravity-flow setup.

Results

SEM images of the PRESERFLO showed luminal diameters of 67.73 × 65.95 µm and 63.66 × 70.54 µm. The total diameter was 337.2 µm, and the wall was 154 µm wide. The theoretical calculation of the resistance to flow (R) for an aqueous humor (AH) viscosity of 0.7185 centipoises (cP) was 1.3 mm Hg/(µL/min). Hence, assuming a constant AH flow of 2 µL/min, the pressure differential across the device (ΔP) was estimated to be 2.6 mm Hg. The gravity-flow experiment allowed us to measure the experimental resistance to flow, which was R_E = 1.301 mm Hg/(µL/min), in agreement with the theoretical resistance to flow R given by the HP equation.

Conclusions

The experimental and theoretical flow testing showed that the pressure drop across this device would not be large enough to avoid hypotony unless the resistance to outflow of the sub-Tenon space was sufficient to control the intraocular pressure in the early postoperative period.

Translational Relevance

The fluid properties of glaucoma subconjunctival drainage devices determine their specific bleb-forming capacity and ability to avoid hypotony and therefore their safety and efficacy profile.

Surgical technique, perioperative management and early outcome data of the PAUL® glaucoma drainage device

Objectives

To describe a surgical technique and early post-operative outcomes for a novel glaucoma drainage device—the PAUL® glaucoma implant (PGI).

Methods

A consecutive cohort study of subjects who had PGI surgery between February 2019 and May 2020 with a minimum of 6-month follow-up. Primary outcome measures included failure (intraocular pressure (IOP) > 21 mmHg or a <20% reduction of IOP, removal of the implant, further glaucoma intervention or visual loss to no light perception). Secondary outcomes included mean IOP, mean number of medications, logMAR visual acuity (VA) and complications.

Results

Ninety-nine eyes of 97 patients had a preoperative IOP (mean ± standard deviation) of 28.1 ± 9.0 mmHg, falling to 18.2 ± 6.8 mmHg at 1 month, 17.9 ± 6.7 mmHg at 3 months and 13.6 ± 4.7 mmHg at 6 months. 52 patients had a 12-month mean IOP of 13.3 ± 4.4 mmHg. The mean change in number of medications was a reduction of 2.38 ± 1.48. A significant reduction in the number of medications and intraocular pressure was demonstrated after PGI (p < 0.0001). No significant change was demonstrated in VA (p = 0.1158). A total of nine cases were deemed failures (six had <20% IOP reduction from baseline and three had IOP >21 mmHg). Thirty-eight (38.4%) of eyes had complete success and achieved an unmedicated IOP <21 mmHg. Ninety (90.1%) of eyes were qualified successes (with or without topical medications). Seventy-four (74.7%) eyes have achieved an intraocular pressure of <15 mmHg. Two cases of hypotony were observed.

Conclusion

This study presents a safe surgical technique, which significantly reduces IOP and number of medications with minimal complications.

Intraocular Pressure Monitoring Using an Intraocular Sensor Before and After Glaucoma Surgery

PURPOSE

Intraocular pressure (IOP) is the only modifiable risk factor for glaucoma, with evidence from landmark randomized controlled trials demonstrating visual field preservation with IOP reduction. Over recent years, the use of remote sensors has formed an increasingly important component of the management of chronic diseases. During the COVID-19 pandemic, the ability to remotely monitor IOP proved particularly useful when public stay at home orders have been in place.

PATIENTS AND METHODS

This report describes the first case of glaucoma surgery in a patient who had previously received an eyemate-IO implant. The eyemate-IO (Implandata Ophthalmic Products) is an implant for intraocular pressure (IOP) monitoring placed in the ciliary sulcus during cataract surgery.

RESULTS

Remote IOP monitoring enabled the clinician to identify sustained high IOP readings and the need for glaucoma surgery. Post-operatively, response to treatment could be monitored to ensure sufficient long-term IOP control.

CONCLUSIONS

The eyemate-IO implanted during cataract surgery in this patient provided valuable remote continuous IOP information that guided timely glaucoma surgical interventions for poorly controlled IOP.