Membrane-tube-type glaucoma shunt device for refractory glaucoma surgery.

PURPOSE: To evaluate the safety and efficacy of a novel membrane-tube (MT)-type glaucoma shunt device for refractory glaucoma surgery. The device consists of an expanded polytetrafluoroethylene membranous reservoir, as well as a silicone tube (300-µm external and 200-µm internal diameter) with an intraluminal stent. We named the device "Finetube MT". METHODS: The Finetube MT was implanted into 44 glaucomatous eyes that had insufficient intraocular pressure (IOP) control despite medical treatment or previous trabeculectomy. The membranous reservoir was placed underneath the Tenon's capsule, with each end located below the recti muscles; the tube was placed in the anterior chamber through a partial-thickness scleral track. We investigated the baseline and post-operative IOP values, the number of IOP-lowering medications used, and complications. RESULTS: The mean age of the subjects was 51.6 ± 17.2 years, and the mean follow-up duration was 22.5 ± 12.0 months. One year after the surgery, the mean IOP had decreased from 32.8 ± 12.2 mmHg to 16.9 ± 6.4 mmHg (48.5 % reduction; p < 0.01), and the mean number of IOP-lowering medications used had decreased from 2.5 ± 0.8 to 1.1 ± 0.9 (p < 0.01). We considered the surgery as a success when the IOP was between 6 and 21 mmHg, and had been reduced by ≥ 20 % from baseline; by this standard, the success rate was 92.4 % after 1 year, and 85.0 % after 3 years. Neither postoperative ocular hypotony-related complications nor tube exposure occurred in any case. CONCLUSIONS: The Finetube MT showed promising surgical outcomes as a treatment for refractory glaucoma, with minimal risk of postoperative ocular hypotony or tube-related complications.

Novel membrane-tube type glaucoma shunt device for glaucoma surgery.

BACKGROUND: The background of this study is to introduce the surgical technique and outcomes of a novel membrane-tube (MT) type glaucoma shunt device (MicroMT), which was developed to achieve safer and more predictable intraocular pressure (IOP) control compared with conventional trabeculectomy. DESIGN: This is a retrospective, non-comparative, interventional case series study. PARTICIPANTS: The MicroMT was implanted in 43 glaucomatous eyes with insufficient IOP control despite medical treatment. METHODS: The MicroMT consists of an expanded polytetrafluoroethylene membrane and a silicone tube with an intraluminal stent, which allows aqueous drainage from the anterior chamber to the lamellar scleral flap. The intraluminal stent prevents excessive aqueous drainage and allows additional IOP reduction through retraction or removal of the stent. MAIN OUTCOME MEASURES: The main outcome measures of this study are IOP changes and complications. RESULTS: The mean (SD) IOP decreased from a preoperative value of 22.5 (6.9) mmHg to 11.1 (3.6) mmHg 3 years after the operation (50.7% reduction from baseline; P < 0.01). Intraluminal stent removal 4 weeks after the operation induced an additional 40.2% IOP reduction (P < 0.01). When success was defined as an IOP between 6 and 21 mmHg, and an IOP reduction of ≥20% from baseline, the success rate was 89.5% at 3 years after the operation. No postoperative ocular hypotony (IOP <6 mmHg) or tube-related complications occurred. CONCLUSIONS: MicroMT implantation is a novel therapy that may reduce IOP safely and effectively, with no apparent risk of postoperative ocular hypotony. Glaucoma surgery using this device may be a good alternative to conventional glaucoma surgery.

Filtering Bleb Size in the Early Postoperative Period Affects the Long-term Surgical Outcome after Trabeculectomy.

PURPOSE: To investigate whether postoperative filtering bleb size affects the surgical outcome after trabeculectomy. METHODS: In this study, we retrospectively reviewed 145 medically uncontrolled glaucoma patients with intraocular pressure (IOP) values >21 mmHg before surgery and data from ≥2 years of follow-up. Postoperative IOP, filtering bleb size including extent and height, and other clinical factors were measured after trabeculectomy. We divided bleb extent into quadrants and bleb height by 0.5 intervals of corneal thickness. The main outcome measure was surgical success. We confirmed complete success when the IOP was ≤21 mmHg and decreased by >20% from baseline without medication or additional procedures. Qualified success used the same criteria but allowed for medication or additional procedures. Cases with reoperation or two consecutive IOP measurements <6 mmHg were considered failures. RESULTS: A total of 145 eyes of 145 patients was included. The average observation period was 30.8 ± 10.9 months. During multivariate Cox regression analysis, a larger extent of filtering bleb revealed significantly low hazard ratios in both complete and surgical success (0.509 and 0.494, respectively); however, there was no significant relationship between bleb height and surgical outcome. CONCLUSIONS: The extent of the filtering bleb was associated with surgical outcomes of trabeculectomy in glaucoma patients.

Fluid Dynamics of Small Diameter Tubes Used in Membrane-tube Type Glaucoma Shunt Devices.

PURPOSE: To investigate the outflow characteristics of silicone tubes with intraluminal stents used in membrane-tube (MT) type glaucoma shunt devices. METHODS: The silicone tubes used in MicroMT (internal diameter of 100 µm with a 7-0 nylon intraluminal stent) and Finetube MT (internal diameter of 200 µm with a 5-0 nylon intraluminal stent) were connected to a syringe-pump that delivered a continuous flow of distilled water at flow rates of 2, 5, 10, and 25 µL/min. The pressures and resistances of tubes were measured at a steady flow rate with full-length, half-length, and absence of intraluminal stents. RESULTS: The mean outflow resistance of the two types of tubes ranged from 3.0 ± 1.9 to 3.8 ± 1.7 mmHg/µL/min with a full-length intraluminal stent, 1.8 ± 1.1 to 2.2 ± 1.1 mmHg/µL/min with a half-length intraluminal stent, and 0.1 ± 0.0 to 0.2 ± 0.0 mmHg/µL/min without an intraluminal stent. Theoretically, for a physiologic state with a flow rate of 2 µL/min and episcleral venous pressure of 6 mmHg, the mean pressures of tubes were expected to be 13.2 ± 3.0, 10.5 ± 2.4, and 6.4 ± 0.2 mmHg in MicroMT with full-length, half-length, and absence of intraluminal stents, respectively, and 12.5 ± 3.9, 9.6 ± 2.4, and 6.2 ± 0.2 mmHg in Finetube MT with full-length, half-length, and absence of intraluminal stents, respectively. The pressure variance also decreased with intraluminal stent retraction (p < 0.01). CONCLUSIONS: The small diameter tubes of 100 and 200 µm internal diameters, with 7-0 and 5-0 nylon intraluminal stents, respectively, used in the MT-type glaucoma shunt device showed safe and effective outflow characteristics.

Surgical outcomes of membrane-tube-type glaucoma shunt device in indigenous West Africans.

PURPOSE: The aim of this study was to report the safety and efficacy of the membrane-tube (MT)-type glaucoma shunt device (Finetube MT) in the management of refractory glaucoma in indigenous West Africans. METHODS: The Finetube MT was implanted into 25 eyes of 25 West African patients with refractory glaucoma. These patients had inadequate intraocular pressure (IOP) control despite maximum tolerable IOP-lowering medications with or without previous ocular surgeries. IOP, postoperative complications, interventions, visual acuities, and the number of IOP-lowering medications were analyzed preoperatively and postoperatively. RESULTS: The mean (standard deviation [SD]) age of the patients was 49.7 (20.9) years. The mean (SD) follow-up duration was 21.0 (10.6) months. Postoperatively, the mean (SD) IOP reduced from a preoperative value of 38.1 (10.3) mmHg to 14.5 (4.6), 16.1 (7.8), and 14.7 (3.0) mmHg at 1, 2, and 3 years postoperatively, respectively, representing 61.9%, 57.7%, and 61.4% reduction from baseline (P<0.01). The mean (SD) number of IOP-lowering medications reduced from 4.1 (1.0) to 0.6 (0.9) at 1 year and 0.9 (1.1) at 2 years after the operation (P<0.01). Using an IOP level between 6 and 21 mmHg and reduced by ≥20% from baseline, the cumulative survival rate (standard error) was 96.0% (3.9%) at 6 months, 89.0% (6.0%) at 18 months, and 81.3% (10.6%) at 3 years after the operation. There was no postoperative ocular hypotony, tube occlusion, or device exposure. CONCLUSION: The Finetube MT may effectively control IOP with minimal risk of postoperative complications in indigenous West Africans.

Long-term comparison of postoperative refractive outcomes between phacotrabeculectomy and phacoemulsification.

PURPOSE: To compare long-term postoperative refractive outcomes between phacotrabeculectomy and phacoemulsification, both with posterior chamber intraocular lens implantation. SETTING: Department of Ophthalmology, Konyang University, Kim's Eye Hospital, Myung-Gok Eye Research Institute, Seoul, South Korea. DESIGN: Retrospective comparative study. METHODS: Postoperative refractive outcomes were compared between patients with cataract and coexisting primary or secondary open-angle glaucoma (OAG) who had phacotrabeculectomy (combined group) and patients with cataract with or without coexisting OAG who had phacoemulsification alone (phaco-only group). The refractive prediction error, mean absolute error, and median absolute error were compared between groups. Subgroup analysis based on preoperative axial length (AL) was performed (medium >22.0 to <24.5 mm; medium-long ≥24.5 to <26.0 mm; long ≥26.0 mm). RESULTS: The combined group comprised 51 eyes and the phaco-only group, 74 eyes. The mean interval between surgery and refraction measurement was 14.70 months ± 10.80 (SD) (median 13.0 months) and 4.81 ± 4.97 months (median 2.0 months), respectively. Postoperatively, there was no statistically significant between-group difference in the following mean values: refractive prediction error, -0.05 ± 0.64 versus -0.04 ± 0.52 (P = .905); mean absolute error, 0.46 ± 0.44 versus 0.38 ± 0.36 (P = .258); median absolute error, 0.32 (interquartile range [IQR], 0.17, 0.67) versus 0.28 (IQR, 0.13, 0.54) (P = .297). Subgroup analysis also did not show significant differences between the 2 groups (all P > .05). CONCLUSION: The long-term postoperative refractive outcomes of phacotrabeculectomy and phacoemulsification alone were not significantly different in eyes with OAG, regardless of preoperative AL.

Safety and Efficacy of a Membrane-Tube-Type Glaucoma Shunt Device: An Animal Trial.

PURPOSE: To evaluate the safety and efficacy of a membrane-tube-type glaucoma shunt device (MT-device), which was developed to control intraocular pressure (IOP) with a lower chance of complications than conventional glaucoma surgery, in a rabbit model. MATERIALS AND METHODS: The MT-device consists of an expanded polytetrafluoroethylene membrane (thickness 0.2 mm, area 2.5 × 2.5 mm2) and a tube (internal diameter 76 µm, external diameter 175.5 µm, length 7 mm) attached to the membrane. The device was implanted into the left eyes of nine New Zealand white rabbits. The tube was placed in the anterior chamber through paracentesis, and the membrane was fixated on the scleral surface; this induces aqueous drainage from the anterior chamber to the subconjunctival space. IOP, filtering bleb morphology, depth and inflammation of the anterior chamber, and possible complications were evaluated periodically for 8 weeks after surgery. Histological sections were analyzed at 2 and 8 weeks after the surgery. RESULTS: Mean IOP decreased from a preoperative value of 8.7 ± 1.2-4.7 ± 0.6 mmHg at postoperative 8 weeks (p < 0.05). The filtering bleb was maintained during the study period. There were no major postoperative complications. Histologic assessment revealed that 2 weeks after the surgery, fibrous encapsulation, inflammatory cells, and fibroblasts were observed around the MT-device; however, 8 weeks after the surgery, minimal inflammation was observed. CONCLUSIONS: The MT-device showed good biocompatibility and effective IOP reduction with a low risk of complications in a rabbit model.

Performance of and Pressure Elevation Formed by Small-diameter Microtubes Used in Constant-flow Sets.

PURPOSE: We explored the performance of and pressure elevation caused by small-diameter microtubes used to reduce overfiltration. METHODS: Using a syringe pump-driven constant-flow setting (2 µL/min), pressures were measured for polytetrafluoroethylene (PTFE) microtubes 5 mm in length with inner diameters of 51, 64, and 76 µm and for polyether block amide (PEBAX) microtubes with an inner diameter of 76 µm. Experiments (using microtubes only) were initially performed in air, water, and enucleated pig eyes and were repeated under the same conditions using intraluminal 9/0 nylon stents. RESULTS: The pressures measured in air in 51-, 64-, and 76-µm-diameter PTFE microtubes differed significantly (22.1, 16.9, and 12.2 mmHg, respectively; p < 0.001), and that of the 76-µm-diameter PEBAX microtube was 15.8 mmHg (p < 0.001 compared to the 12.2 mmHg of the 76-µm-diameter PTFE microtube). The pressures measured in water also differed significantly among the three microtubes at 3.9, 3.0, and 1.4 mmHg, respectively, while that in the PEBAX microtube was 2.6 mmHg (all p < 0.001). Using the intraluminal stent, the pressure in water of the three different PTFE microtubes increased to 22.6, 18.0, and 4.1 mmHg, respectively, and that in the PEBAX microtube increased to 10.5 mmHg (all p < 0.001). Similar trends were evident when measurements were performed in pig eyes. CONCLUSIONS: Although microtubes of smaller diameter experienced higher pressure in air, reduction of the inner diameter to 51 µm did not adequately increase the pressure attained in water or pig eyes. Insertion of an intraluminal stent effectively elevated the latter pressures. PEBAX microtubes created higher pressures than did PTFE microtubes.

A comparison of the clinical effect between e-PTFE membrane-tube implant and Ahmed glaucoma valve implant for the treatment of refractory glaucoma.

In order to compare the clinical efficacy of expanded polytetrafluoroethylene membrane-tube implant (MT implant) and Ahmed implant in the treatment of refractory glaucoma, the medical records of the patients who had been followed-up for more than 1 year after glaucoma implant surgery were reviewed retrospectively. Either MT or Ahmed implants were selected randomly and implanted by one surgeon in patients with refractory glaucoma. There was no significant difference in clinical variables such as age, intraocular pressure and ocular surgery history between the MT implant and Ahmed implant groups (n = 20 eyes of 19 patients in each group) before surgery. The course of change in intraocular pressure and the number of anti-glaucoma medications were not significantly different between the 2 groups during the entire study period (p > 0.1). Kaplan-Meier analysis for intraocular pressure control between 6 and 21 mmHg showed 90% and 95% at 6 months, and 85% and 85% at 12 months, in the MT and Ahmed groups, respectively (p = 0.982). A few self-limiting complications, all within the first month after surgery, were noted in each group. In this study, MT implant showed comparable results to Ahmed implant. MT implant may be useful as a good substitute for other currently used implants without any loss in efficacy or increase in risk, and with potential advantage coming from its soft consistency and small volume.

A new instrument for drainage or injection of fluid within subretinal space.

PURPOSE: To describe a new instrument, the subretinal aspiration and injection device (SR-AID), designed to facilitate the controlled external drainage or injection of fluid in the subretinal space. METHODS: The SR-AID is formed by an assembly of a probe, handle body, and a driving unit. The curved conduit within the probe segment forms a curved tunnel and acts as a guide along which a needle moves back and forth. The feasibility of fluid injection beneath the attached retina was tested in animal eyes. The efficacy of subretinal fluid drainage with the SR-AID were assessed in six cases of clinical retinal detachment. RESULTS: External approach to the subretinal space under ophthalmoscopic monitoring can be achieved by oblique angle penetration of the scleral wall with a needle from the SR-AID. Fluid was injected successfully into the subretinal space in three of six rabbit eyes and in two of two pig eyes. The mean duration required for the drainage of subretinal fluid with the SR-AID was 127 seconds. There was no incidence of significant subretinal hemorrhage or retinal perforation in the animal experiments and in human cases. CONCLUSION: Our case series suggests that the SR-AID provides an efficient and safe means of access to the subretinal space.