Glaucoma drainage devices / Dispositivos de drenagem para glaucoma

ABSTRACT Glaucoma drainage devices are important therapeutic options for cases of refractory glaucoma, in which trabeculectomy with antimetabolites has shown high risk of failure. There are devices with different sizes, designs and materials, and several studies have been conducted to test their safety and effectiveness. Despite known complications, their use has progressively increased in recent years, and they are the primary surgical option, in some situations. The aim of this review is to discuss the importance, mechanisms, biomaterials, results and complications of glaucoma drainage devices.

RESUMO Os dispositivos de drenagem para glaucoma são importante opção terapêutica em casos de glaucomas refratários, nos quais a trabeculectomia com antimetabólitos tem alta chance de falência. Há dispositivos com diferentes tamanhos, desenhos e materiais, e muitos estudos foram realizados para testar sua segurança e eficácia. Apesar de suas conhecidas complicações, seu uso tem aumentado progressivamente nos últimos anos, inclusive como primeira opção cirúrgica, em algumas situações. O objetivo desta revisão foi discutir a importância, os mecanismos, os biomateriais, os resultados e as complicações dos dispositivos de drenagem para glaucoma.

Ocular motility changes and diplopia in sutured versus unsutured implantation of the Baerveldt glaucoma device.

PURPOSE: To investigate the effect of two surgical techniques in primary Baerveldt glaucoma implant (BGI) surgery, that is the sutured technique and the unsutured (free) plate technique, on the ocular motility and prevalence of diplopia. We hypothesize that the free plate technique results in a lower diplopia prevalence. METHODS: We performed a prospective study of patients who underwent BGI surgery with the free plate technique and compared them with patients from a previous study who had undergone BGI surgery with the sutured technique. Their ductions, ocular alignment and fusion range and the prevalence of diplopia were measured before surgery and at 3 months, 6 months and 1 year postoperatively. RESULTS: We analysed 57 free plate and 51 sutured plate patients. One year postoperatively, we found no statistically significant difference in the prevalence of diplopia between the two techniques. All duction changes between baseline and 1-year follow-up were restrictions and occurred statistically significantly more frequently in the free plate than in the sutured plate group (p = 0.03; 60% versus 34%). About the ocular alignment, in the horizontal direction, a change in exodirection was more common in both groups, while in the vertical direction, a hyperdeviation of the operated eye was more common. The vertical ocular alignment change was smaller in the free plate group than in the sutured plate group (p = 0.04 at near and p = 0.02 at distance). CONCLUSIONS: One year postoperatively, the prevalence of diplopia was not significantly different between patients with the sutured plate and patients with the free plate technique. Both surgical techniques induce diplopia and changes in ocular motility and/or in ocular alignment.

Alteration of gene expression in mice after glaucoma filtration surgery.

To clarify the early alterations of gene expression using a mouse model of glaucoma filtration surgery, we carried out microarray expression analysis. Using BALB/c mice, a filtration surgery model was made by incision of the limbal conjunctiva, followed by the insertion of a 33G needle tip into the anterior chamber, and 11-0 nylon sutures. Subgroups of mice were treated intraoperatively with 0.4 mg/ml mitomycin-C (MMC). At day 3 after surgery the bleb was maintained. The bleb region tissue was sampled 3 days after the filtration surgery, and gene expression analysis was carried out using a mouse Agilent 8 × 60 K array. We found 755 hyperexpressed transcripts in the bleb region compared to control conjunctiva. The hyperexpressed transcripts included epithelial cell metaplasia-related (Il1b, Krt16, Sprr1b), inflammation-related (Ccl2, Il6) and wound healing-related (Lox, Timp1) genes. We also found downregulation of a goblet cell marker gene (Gp2) in the bleb conjunctiva. MMC treatment suppressed elastin (Eln) gene expression and enhanced keratinization-related gene expression (Krt1, Lor) in the bleb region. Our results suggest the importance of epithelial wound healing after filtration surgery, and this filtration surgery model will be a useful tool for further pathophysiological analysis.

Translating Minimally Invasive Glaucoma Surgery Devices.

Glaucoma is the leading cause of irreversible blindness with over 70 million people affected worldwide. The surgical management of glaucoma aims to lower intraocular pressure by increasing aqueous outflow facility. The latest manufacturing techniques have allowed for the development of a number of novel implantable devices to improve safety and outcomes of glaucoma surgery. These are collectively referred to as minimally invasive glaucoma surgery (MIGS) devices and are among the smallest devices implanted in the human body. This review discusses the design criterion and constraints as well as the user requirements for MIGS devices. We review how recent devices have attempted to meet these challenges and give our opinion as to the necessary characteristics for the development of future devices.

Novel approaches to model effects of subconjunctival blebs on flow pressure to improve clinical grading systems after glaucoma drainage surgery.

Clinical grading systems following glaucoma filtration surgery do not include any effects of the bleb on the intra-ocular pressure and are relatively subjective, therefore carrying the risk of inter and/or intra-observer variability. The main objective of the study is to quantify and model the effect of subconjunctival bleb on flow pressure for assessment of clinical grading following glaucoma surgery. Subconjunctival bleb was created by inserting a tube into ex vivo rabbit eyes via an ab externo approach through the anterior chamber and exiting into the subconjunctival space. Sterile dyed water was injected through the tube into the developing bleb. For the in vitro approach a silicone bleb was created by clamping a circular silicone sheet, injecting dyed water through a fixed resistance outlet tube. Photographic measurements of the bleb height, planform area and pressure were taken as a function of time. Clinical blebs were also collected over a few months. Mathematical algorithm software was used to build the bleb model. Bleb height and volume increase as pressure in the bleb increases. The bleb planform area tended to a constant determined by the section of conjunctiva prior to shunt insertion. These increases were in accordance with the bleb model developed in the Appendix. They show that the pressure in the bleb is related to the resistance of the outflow. The linearity of clinical grading systems is reviewed and a new grading approach is proposed. The pressure in the bleb has a strong dependence on bleb extent, height and a weak dependence on conjunctival thickness. The pressure in a bleb can be estimated from bleb height, radius, and flow rate inlet in agreement with the bleb flow model. These results provide support for an improved bleb categorization system.

Outcomes of Wider Area Bleb Revision Using Bleb Knife With Adjunctive Mitomycin C.

PRECIS: Wider area bleb revision using bleb knife with adjunctive mitomycin C (MMC) had a good success rate, according to strict success criteria, except in patients with neovascular glaucoma (NVG). PURPOSE: We determined the efficacy of wider area bleb revision after filtering surgery using bleb knife with adjunctive MMC. PATIENTS AND METHODS: In this retrospective single-center study, we analyzed 86 patients with glaucoma (46 primary open-angle, 18 exfoliations, 13 secondary, and 9 neovascular) after bleb revision using bleb knife with adjunctive MMC after a minimum follow-up of 6 months. A Kaplan-Meier survival analysis with log-rank tests and Cox proportional hazards regression analyses were performed. The main outcome measure was a successful initial bleb revision using bleb knife with adjunctive MMC, arbitrarily defined as intraocular pressure (IOP) control <15 mm Hg without any IOP-lowering medication, additional bleb revision, or glaucoma surgery. RESULTS: The mean time since the initial filtering surgery was 243.8 days, and the mean prebleb revision IOP was 22.0±4.8 mm Hg. The total cumulative success rate of the bleb revision using bleb knife with MMC was 49% at 6 months and 30% at 1 year. Patients with primary open-angle glaucoma had the best success rate (64% at 6 mo and 40% at 1 y). Log-rank tests revealed that patients with NVG had the worst prognosis (P<0.01). NVG was the only significant risk factor identified for short survival time (odds ratio, 167.10; 95% confidence interval, 1.78-15620.44; P=0.027). CONCLUSION: Wider area bleb revision using bleb knife with adjunctive MMC had a good success rate, according to strict success criteria, except in patients with NVG.

Transfixion technique for the treatment of silicone oil pupillary block glaucoma refractory to Nd-YAG iridotomy.

BACKGROUND: Pupillary block induced by silicon oil in vitrectomized patients is a common condition usually treated with Nd-YAG laser iridotomy or with surgical removal of silicon oil. CASE REPORT: A case of silicone oil pupillary block glaucoma successfully treated with a 30 G needle transfixion technique is described. We performed a non-complicated vitrectomy surgery for retinal detachment with proliferative vitreoretinopathy that included lensectomy, inferior peripheral iridectomy, and silicone oil injection. After surgery, the iridectomy became occluded with fibrous tissue and the intraocular pressure raised to 50 mmHg. After an initial Nd-YAG iridotomy was unsuccessful, we passed a 30 Ga needle through the sclerocorneal limbus and cut the fibrous tissue that blocked the iridectomy. This procedure restored the aqueous humor flow through the iridectomy, pushed back the silicone oil bubble into the vitreous cavity and lowered the intraocular pressure to normal levels. CONCLUSIONS: 30 Ga needle transfixion technique could be an effective, low cost, simple alternative for the treatment of silicone oil pupillary block in aphakic patients.

ANTECEDENTES: El bloqueo pupilar secundario a aceite de silicón en pacientes vitrectomizados es una condición frecuente que normalmente se trata con apertura de la iridectomía con láser Nd-YAG o con el retiro del aceite de silicón. CASO CLÍNICO: Se describe un caso de glaucoma secundario a bloqueo pupilar por aceite de silicón tratado satisfactoriamente con técnica de transfixión con aguja de calibre 30. Realizamos una cirugía de vitrectomía sin complicaciones para el tratamiento de un desprendimiento de retina con vitreorretinopatía proliferativa, que incluyó lensectomía, iridectomía periférica inferior e inyección de aceite de silicón. Después de la cirugía, la iridectomía se ocluyó con tejido fibroso y la presión intraocular se incrementó a 50 mmHg. Después de que una iridotomía inicial con láser Nd-YAG no tuvo éxito, pasamos una aguja de calibre 30 a través del limbo esclerocorneal y cortamos el tejido fibroso que bloqueaba la iridectomía. Este procedimiento restauró el flujo de humor acuoso a través de la iridectomía, desplazando la burbuja de aceite de silicón a la cavidad vítrea, y la presión intraocular descendió a valores normales. CONCLUSIONES: La técnica de transfixión con aguja de calibre 30 puede ser una alternativa efectiva, simple y de bajo costo para el tratamiento del bloqueo pupilar con aceite de silicón en pacientes con afaquia.

Ab interno gel implant in patients with primary open angle glaucoma and pseudoexfoliation glaucoma.

PURPOSE: To compare efficacy and safety results of an ab interno gel implant in patients with pseudoexfoliation glaucoma (PXG) and primary open angle glaucoma (POAG). METHODS: Retrospective analysis of the medical records of 110 consecutive eyes with open angle glaucoma who had received a XEN45 gel implant between March 2014 and June 2015. Intraocular pressure course, number of glaucoma medications, the need for additional intervention (including needling) and complications were evaluated until 12 months postoperatively. RESULTS: Data of 67 eyes with POAG and 43 eyes with PXG were analyzed. At 12 months postoperatively, the mean IOP had significantly decreased by 54.0% from preoperatively 31.85 ± 8.5 mmHg to 13.99 ± 2.6 mmHg in the POAG group, (p = 0.000; Wilcoxon test), and by 55.2% from 31.63 ± 9.0 mmHg to 13.28 ± 3.1 mmHg in the PXG group (p = 0.000; Wilcoxon test). The mean number of anti-glaucoma medications had significantly decreased from 3.25 ± 0.8 at baseline to 0.3 ± 0.7 medications at 12 months postoperatively in POAG eyes (p = 0.000; Wilcoxon test), and from 3.05 ± 1.0 to 0.3 ± 0.6 medications in PXG eyes (p = 0.000; Wilcoxon test). Hypotony (IOP ≤ 6 mmHg) was observed in 2 POAG eyes (3.0%) and in 5 PXG eyes (11.7%) at 1 month but normalized in all eyes at 12 months postoperatively. Severe complications were not observed. No statistically significant differences were found between PXG eyes and POAG eyes. CONCLUSION: Our data indicate that the XEN45 gel implant provides significant and comparable reduction in IOP and anti-glaucoma medication during the one-year follow-up period in POAG as well as PXG eyes. This suggests that it may be a noteworthy alternative to traditional filtering procedures in patients with POAG and PXG respectively.

Efficacy and Safety of the Ab-interno Xen Gel Stent After Failed Trabeculectomy.

AIMS: To assess the efficacy and safety of the Xen gel stent in reducing intraocular pressure (IOP) in eyes with prior failed trabeculectomy and to determine the frequency of complications and further intervention. METHODS: Retrospective case note review of all patients with prior trabeculectomy undergoing Xen surgery across 5 centers from August 2015 to May 2017. RESULTS: In total, 17 surgeries were reviewed. IOP reduced from 21.5 (±2.4) mm Hg preoperatively to 13.6 (±3.4) mm Hg at month 12 (P<0.05). Medication usage reduced from 2.8 (±0.6) preoperatively to 1.0 (±1.3) at month 12 (P<0.05). Adverse events included: numerical hypotony (IOP<6 mm Hg) in 4 cases (23.5%) that all resolved spontaneously, IOP spike of ≥30 mm Hg in 2 (11.8%) cases and transient occlusion of the implant by iris in 1 (5.9%) case. Secondary filtration surgery (Baerveldt tube implantation) was required in 2 (11.8%) cases. Postoperative bleb intervention was required in 9 cases (52.9%), usually in the first month after surgery. CONCLUSIONS: Xen reduces IOP and number of medications in eyes with failed trabeculectomy. Detailed preoperative conjunctival assessment and targeted stent placement is required. Prospective data and follow-up beyond 12 months are required but Xen seems a viable, effective, and safe option after failed trabeculectomy.

The impact of conjunctival flap method and drainage cannula diameter on bleb survival in the rabbit model.

PURPOSE: To examine the effect of cannula diameter and conjunctival flap method on bleb survival in rabbits undergoing cannula-based glaucoma filtration surgery (GFS). METHODS: Twelve New Zealand White rabbits underwent GFS in both eyes. The twenty-four eyes were divided into four groups. Two of the four groups (N = 12) received limbus-based conjunctival flaps (LBCF), and the other two (N = 12) received fornix-based conjunctival flaps (FBCF). Six FBCF rabbit eyes were implanted with 22-gauge drainage tubes, and the other six were implanted with 26-gauge tubes. Likewise, six LBCF rabbits received 22-gauge drainage tubes and six received 26-gauge tubes. Filtration blebs were evaluated every three days by a masked observer. Bleb failure was defined as the primary endpoint in this study and was recorded after two consecutive flat bleb evaluations. RESULTS: Group 1 (LBCF, 22- gauge cannula) had a mean bleb survival time (Mean ± SD) of 18.7 ± 2.9 days. Group 2 (LBCF, 26-gauge cannula) also had a mean bleb survival time of 18.7 ± 2.9 days. Group 3 (FBCF, 22-gauge cannula) had a mean bleb survival time of 19.2 ± 3.8 days. Group 4 (FBCF, 26-gauge cannula) had a mean bleb survival time of 19.7 ± 4.1 days. A 2-way analysis of variance showed that neither surgical approach nor cannula gauge made a statistically significant difference in bleb survival time (P = 0.634 and P = 0.874). Additionally, there was no significant interaction between cannula gauge and conjunctival flap approach (P = 0.874), suggesting that there was not a combination of drainage gauge and conjunctival flap method that produced superior bleb survival. CONCLUSION: Limbus and fornix-based conjunctival flaps are equally effective in promoting bleb survival using both 22 and 26-gauge cannulas in the rabbit model. The 26-gauge drainage tube may be preferred because its smaller size facilitates the implantation process, reducing the risk of corneal contact.

Comparison of the Ahmed and Baerveldt glaucoma shunts with combined cataract extraction.

OBJECTIVE: To compare the surgical outcomes of combined phacoemulsification with either Ahmed glaucoma valve (AGV) or Baerveldt glaucoma implant (BGI). DESIGN: Retrospective cohort study. PARTICIPANTS: A total of 104 eyes that underwent combined phacoemulsification with either AGV (PhacoAGV; n = 57) or BGI (PhacoBGI; n = 47) implantation. METHODS: Failure was defined as uncontrolled intraocular pressure (IOP; <5 mm Hg, ≥18 mm Hg, or <20% reduction), additional glaucoma surgery, vision-threatening complications, or progression to no-light-perception vision. RESULTS: The PhacoAGV group was older (p = 0.03), had poorer baseline visual acuity (VA; p = 0.001), and had fewer previous glaucoma surgeries (p = 0.04). Both groups had similar baseline IOP (PhacoAGV: 26.4 ± 8.3 mm Hg; PhacoBGI: 25.7 ± 7.3; p = 0.66) and glaucoma medications (PhacoAGV: 3.8 ± 1.0; PhacoBGI: 3.6 ± 1.5; p = 0.54). At 2 years, failure rates were 44% in the PhacoAGV group and 23% in the PhacoBGI group (p = 0.02). Both groups had similar mean IOP reduction (PhacoAGV: 45%; PhacoBGI: 47%, p = 0.67) and medication use reduction (PhacoAGV: 47%; PhacoBGI: 58%, p = 0.38). The PhacoBGI group had higher IOP and medication use up to 1 month (p < 0.05). Both groups improved in VA from baseline (p < 0.05) and had similar overall complication rates (p = 0.31). The PhacoBGI group required more overall interventions (p < 0.0005). CONCLUSIONS: This comparative study found no difference in IOP, glaucoma medications, or complication rates between PhacoAGV and PhacoBGI at 2 years, despite BGIs being implanted in patients at higher risk for failure. The PhacoAGV group had higher failure rates at 2 years. Both groups had significant improvements in VA due to removal of their cataracts. The PhacoBGI group required more interventions, but most of these were minor slit-lamp procedures.

Supraciliary Implant Placement and Postoperative Suprachoroidal Hemorrhage After Nonpenetrating Deep Sclerectomy.

PURPOSE: The purpose if this study was to evaluate the clinical characteristics and risk factors of 3 eyes (3 patients), with primary open-angle glaucoma (POAG), in whom a postoperative suprachoroidal hemorrhage (SCH) occurred after a previous nonpenetrating deep sclerectomy (NPDS) augmented with a supraciliary nonabsorbable implant placement. METHODS AND SURGICAL TECHNIQUE: This is a report of 3 eyes of the 3 patients who underwent NPDS in 3 different centers, by 3 experienced surgeons, and were the only ones to develop postoperative SCH in the last 18 years. All were operated with a one-third thickness outer scleral flap measuring 5×5 mm dissected until it reached 1 to 2 mm into the clear cornea. Mitomycin C (MMC, 0.02%) was applied for 1 minute and an inner scleral flap measuring 4×4 mm was dissected leaving only 10% of scleral thickness below. Then, the inner wall of Schlemm canal was removed. A supraciliary implant, T-flux (Carl Zeiss Meditec, Zeiss, Spain) in case 2 and Esnoper (AJL Ophthalmics SA, Miñano, Spain) in cases 1 and 3, was placed through a full-thickness escleral incission 2 mm behind the scleral spur. RESULTS: Three eyes with uncontrolled primary open-angle glaucoma had a delayed SCH after an uneventful NPDS. Time lapse from filtering surgery to the SCH ranged from 12 hours in case number 1, to 3 weeks in case 3. Several risk factors for DSH were present, but the only common clinical feature for all of them, was the nonabsorbable implant that was placed in the supraciliary space. A Hema implant (Esnoper) was used in 2 eyes (cases 1 and 3), and T-flux, was implanted in the case 2. Case 1 required vitreoretinal surgery and had poor visual outcome, but cases 2 and 3 recovered with conservative treatment. CONCLUSIONS: Although taking the potential bias arising from the nature of the current cases report into consideration, supraciliary placement of the implant in NPDS could be a risk factor for SCH. Consequently, it seems reasonable to avoid it, especially in the presence of other best recognized factors.

Ab Interno Gel Implant for the Treatment of Glaucoma Patients With or Without Prior Glaucoma Surgery: 1-Year Results.

PURPOSE: The purpose of this study is to evaluate IOP lowering effects and complication management of an ab interno gel implant for the treatment of patients refractory to antiglaucoma medication or glaucoma surgery. METHODS: Retrospective analysis of the medical records of 242 consecutive eyes of 146 patients with uncontrolled intraocular pressure (IOP) despite maximum tolerated medical therapy or prior surgical intervention that underwent XEN45 implantation (as sole procedure or in combination with cataract surgery) between March 2014 and June 2015. Data included IOP, number of glaucoma medications, the need for additional surgery, needling, and complications. RESULTS: During the study period, mean IOP had decreased by 54.1% from 32.19 (±9.1) mm Hg to 14.24 (±4.0) mm Hg (P=0.00; Wilcoxon test). The number of antiglaucoma medications had decreased from a mean of 3.13±1.0 to 0.3±0.7 (P=0.00; Wilcoxon test). Needling was required between week 1 and months 3 in 27.7% of all eyes to enhance the outflow. Hypotony (IOP<6 mm Hg) was observed in 9 eyes (4.0%) at 1 month but normalized in all eyes at 12 months postoperatively. Two eyes experienced hypotony requiring the refill of the anterior chamber. CONCLUSIONS: Our data indicate that the XEN45 gel implant has a favorable safety profile and is an effective treatment option for controlling IOP in glaucoma patients with unregulated IOP despite IOP lowering medical therapy or prior surgical intervention. It offers an effective approach, both as sole procedure and in combination with cataract surgery.

Safety and effectiveness of gold glaucoma micro shunt for reducing intraocular pressure in Japanese patients with open angle glaucoma.

PURPOSE: To assess the safety and effectiveness of the SOLX gold shunt (GS) in reducing intraocular pressure (IOP) in Japanese patients with open angle glaucoma (OAG). METHODS: 24 eyes of 24 subjects [mean age of 68.9 ± 12.7 years; 13 (54%) women; 16 (67%) POAG, 7 (29%) pseudoexfoliation glaucoma, and 1 (4%) steroid response glaucoma] were implanted with the GS either with or without cataract surgery. Best-corrected visual acuity (BCVA), IOP, corneal endothelial cell density (CECD), anterior chamber (AC) flare, surgical complications, and required interventions were monitored at baseline, and 1 day, 1 week, 1, 3 and 6 months, and 1 year postoperatively. RESULTS: Baseline IOP of 21.3 ± 4.1 mmHg and glaucoma medications of 3.5 ± 1.0 were significantly reduced at every follow-up visit. At 1 year postoperatively, IOP was 16.4 ± 5.8 mmHg (23% reduction from baseline, p < 0.0001) with use of 2.1 ± 1.1 medications (40% reduction from baseline, p = 0.0002). Intraoperative hyphema occurred in 5 (21%) eyes. Transient bleb formation occurred in 20 (83%) eyes, and AC cell was reported in 17 (71%) eyes. Inflammation-related complications such as posterior and anterior synechiae, or iritis/keratic precipitates tended to occur during late postoperative periods. At 1 year, BCVA was unchanged or improved in 23 (96%) eyes. AC flare was elevated at 1 week postoperatively and later. CECD declined at 3 months and 1 year postoperatively. CONCLUSIONS: The GS is effective in reducing IOP in Japanese patients with OAG. Chronic inflammation in AC might be associated with late onset complications.

Adjustable Dual Muscle Speculum for Simplified Placement of a 350 Baerveldt Implant.

The authors have designed a muscle hook speculum that simultaneously allows the surgeon to isolate and expose both rectus muscles (either the superior and temporal or medial and inferior) for ease of placement of a 350-mm Baerveldt implant. This instrument facilitates the exposure and subsequent placement of either a superior-temporal tube or an infero-nasal tube in a more independent manner. By using the dual muscle hook speculum, an individual surgeon, without a glaucoma-trained assistant, can hook typically both the superior and lateral recti muscles while gaining simultaneous exposure of the quadrant. The purpose of this report is to describe the instrument, how it is used, and how it can improve efficiency in the operating room.

Iris Clip Lens Implantation with Novel Approach for Aphakia After Previous Filtration Surgery.

Purpose To present a novel and simplified surgical technique of Artisan lens implantation for intraocular lens luxation and aphakia in glaucoma patients with previous superior filtration surgery. Methods Analysis of 12 patients with a history of previous superior filtration surgery for glaucoma, who underwent artisan lens implantation. To allow lens manipulation and implantation without alteration of the filtration bleb, the main sclerocorneal incision was performed laterally and the Artisan lens was held in place for enclavation of the iris stroma via a superior corneal incision without disturbing the filtration bleb. Results Mean pre-operative visual acuity was 0.54 ± 0.85 LogMAR, and intraocular pressure (IOP) was 15.8 ± 7.7 mmHg. At the end of follow-up (11.6 ± 8.1 months), visual acuity had improved to 0.32 ± 0.57 LogMAR and intraocular pressure was 14.7 ± 5.4 mmHg. No disturbance of the filtration bleb was observed. Conclusions Artisan lens implantation can be performed successfully via a combined lateral and superior approach despite the presence of a filtration bleb at the 12 o'clock position.

Mini Drainage Devices for Anterior and Intermediate Filtration.

Mini glaucoma devices for external filtration may be implanted with an ab externo procedure (Ex-PRESS and InnFocus Microshunt) or with an ab interno procedure (XEN Gel stent). The Ex-PRESS is an FDA-approved mini glaucoma device that has been developed in order to simplify anterior guarded filtering procedures, making them faster, safer and easier. It is positioned under a scleral flap and it is introduced in the anterior chamber through a needle hole, avoiding the excision of the corneal-scleral button and the iridectomy. Like other anterior filtering guarded procedures, it may be associated with releasable sutures and with an everting suture (the safe Ex-PRESS procedure) in order to increase safety and efficacy. The InnFocus Microshunt is a new ab externo filtering device currently under investigation; it is very easy to implant and highly promising in terms of safety and efficacy. The XEN Gel stent is an ab interno implanted soft, collagen tube that makes a permanent bypass between the anterior chamber and the subconjunctival space. It is a smart, quick, effective and simple procedure that recently gained FDA approval.