scholarly journals A Novel Study Quantifying Intrinsic Dimensional Variation Among Glaucoma Drainage Devices

Cureus ◽  
2021 ◽  
Author(s):  
Jesse A Terrell ◽  
Charles Richard Blake
Keyword(s):  
Glaucoma Drainage Devices ◽  
Dimensional Variation

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

Eye ◽  
2021 ◽  
Author(s):  
Inês C. F. Pereira ◽  
Rosanne van de Wijdeven ◽  
Hans M. Wyss ◽  
Henny J. M. Beckers ◽  
Jaap M. J. den Toonder
Keyword(s):  
Anterior Chamber ◽  
Aqueous Humour ◽  
Alternative Pathway ◽  
Glaucoma Surgery ◽  
Future Directions ◽  
Plate Design ◽  
Glaucoma Drainage Devices ◽  
Abnormal Increase ◽  
Preventable Blindness ◽  
Glaucoma Implants

AbstractGlaucoma 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.

scholarly journals Combined pars plana glaucoma drainage device placement and vitrectomy using a vitrectomy sclerotomy site for tube placement: a case series

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Enchi Kristina Chang ◽  
Sanchay Gupta ◽  
Marika Chachanidze ◽  
John B. Miller ◽  
Ta Chen Chang ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Pars Plana Vitrectomy ◽  
Case Series ◽  
Tube Placement ◽  
Glaucoma Drainage Device ◽  
Drainage Device ◽  
Glaucoma Drainage Devices ◽  
Pars Plana ◽  
Sclerotomy Site

Abstract Purpose The purpose of this study is to report the safety and efficacy of pars plana glaucoma drainage devices with pars plana vitrectomy using one of the vitrectomy sclerotomy sites for tube placement in patients with refractory glaucoma. Methods Retrospective case series of 28 eyes of 28 patients who underwent combined pars plana glaucoma drainage device and pars plana vitrectomy between November 2016 and September 2019 at Massachusetts Eye and Ear. Main outcome measures were intraocular pressure (IOP), glaucoma medication burden, best corrected visual acuity, and complications. Statistical tests were performed with R and included Kaplan-Meier analyses, Wilcoxon paired signed-rank tests, and Fisher tests. Results Mean IOP decreased from 22.8 mmHg to 11.8 mmHg at 1.5 years (p = 0.002), and mean medication burden decreased from 4.3 to 2.1 at 1.5 years (p = 0.004). Both IOP and medication burden were significantly lower at all follow-up time points. The probability of achieving 5 < IOP ≤ 18 mmHg with at least 20% IOP reduction from preoperative levels was 86.4% at 1 year and 59.8% at 1.5 years. At their last visit, three eyes (10.7%) achieved complete success with IOP reduction as above without medications, and 14 eyes (50.0%) achieved qualified success with medications. Hypotony was observed in 1 eye (3.6%) prior to 3 months postoperatively and 0 eyes after 3 months. Visual acuity was unchanged or improved in 23 eyes (82.1%) at their last follow-up. Two patients had a visual acuity decrease of > 2 lines. Two eyes required subsequent pars plana vitrectomies for tube obstruction, and one eye had transient hypotony. Conclusions The results of pars plana glaucoma drainage device and pars plana vitrectomy using one of the vitrectomy sclerotomy sites for tube placement are promising, resulting in significant IOP and medication-burden reductions through postoperative year 1.5 without additional risk of postoperative complications. Inserting glaucoma drainage devices into an existing vitrectomy sclerotomy site may potentially save surgical time by obviating the need to create another sclerotomy for tube placement and suture one of the vitrectomy ports.

scholarly journals Ologen augmentation of Ahmed glaucoma drainage devices in pediatric glaucomas

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Adam Jacobson ◽  
Carin Rojas ◽  
Brenda L. Bohnsack
Keyword(s):  
Intraocular Pressure ◽  
Pediatric Patients ◽  
Survival Rates ◽  
Collagen Matrix ◽  
Ahmed Glaucoma Valve ◽  
Limited Data ◽  
Conventional Surgery ◽  
Glaucoma Drainage Devices ◽  
Hypertensive Phase

Abstract Background Limited data exists on the effectiveness of the collagen matrix, Ologen, on increasing Ahmed glaucoma valve (AGV) success in childhood glaucomas. Methods Ocular examination and surgical details of pediatric patients who underwent AGV placement ± Ologen augmentation between 2012 and 2020. Complete success was defined as intraocular pressure (IOP) between 5 and 20 mmHg without glaucoma medications and additional IOP-lowering surgeries. Qualified success was defined as above, except IOP control maintained with or without glaucoma medications. Results Twenty-two eyes of 16 patients underwent AGV placement of which 6 eyes had Ologen-augmentation (OAGV) and 16 eyes had conventional surgery (CAGV). Average age was 6.4 ± 5.1 years with 4.2 ± 2.5 follow-up years. There was no difference in age, number of previous surgeries, and preoperative IOP and glaucoma medications. At final follow-up, success rate was 100% (5 eyes complete, 6 eyes qualified) in the OAGV group compared to 31% (0 eyes complete, 5 eyes qualified) in the CAGV group. One and two-year survival rates were 100% for OAGV compared to 62 and 38% for CAGV. Postoperative IOP was significantly lower at 1-month and final follow-up (p = 0.02) as was the number of glaucoma medications at 3, 6, 12-months and final follow-up (p < 0.05) in the OAGV group. Conclusions Ologen-augmentation increased the success and survival rates of AGVs in childhood glaucomas. Further, Ologen mitigated the hypertensive phase and decreased medication dependency. Longer follow-up with a greater number of eyes is required to fully evaluate the effectiveness of OAGV.

A Three-Dimensional Analysis of Thermohydrodynamic Performance of Sector-Shaped, Tilting-Pad Thrust Bearings

1983 ◽  
Vol 105 (3) ◽  
pp. 406-412 ◽  
Author(s):  
Kyung Woong Kim ◽  
Masato Tanaka ◽  
Yukio Hori
Keyword(s):  
Dimensional Analysis ◽  
Environmental Conditions ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Thrust Bearings ◽  
Tilting Pad ◽  
Dimensional Variation ◽  
Lubricant Viscosity

The thermohydrodynamic performance of the bearing is analyzed, taking into account the three-dimensional variation of lubricant viscosity and density. The effect of pivot position and operating and environmental conditions on the performance is studied. The present analysis is compared with the isoviscous or the two-dimensional analysis, and is found to predict the bearing performance more accurately.

Variation Analysis for Compliant Assembly

2000 ◽  
Author(s):  
S. Jack Hu ◽  
Yufeng Long ◽  
Jaime Camelio
Keyword(s):  
Sheet Metal ◽  
Assembly Line ◽  
Assembly Process ◽  
Variation Analysis ◽  
Assembly Lines ◽  
Compliant Assembly ◽  
Single Station ◽  
Dimensional Variation ◽  
Sheet Metal Assembly

Abstract Assembly processes for compliant non-rigid parts are widely used in manufacturing automobiles, furniture, and electronic appliances. One of the major issues in the sheet metal assembly process is to control the dimensional variation of assemblies throughout the assembly line. This paper provides an overview of the recent development in variation analysis for compliant assembly. First, the unique characteristics of compliant assemblies are discussed. Then, various approaches to variation modeling for compliant assemblies are presented for single station and multi-station assembly lines. Finally, examples are given to demonstrate the applications of compliant assembly variation models.

Product-Oriented Sensitivity Analysis for Multistation Compliant Assemblies

2006 ◽  
Vol 129 (8) ◽  
pp. 844-851 ◽  
Author(s):  
Jianpeng Yue ◽  
Jaime A. Camelio ◽  
Melida Chin ◽  
Wayne Cai
Keyword(s):  
Product Performance ◽  
Sensitivity Index ◽  
Final Assembly ◽  
Sensitivity Indices ◽  
Dimensional Variation ◽  
Product And Process ◽  
Pattern Sensitivity ◽  
Sheet Metal Assembly

Dimensional variation in assembled products directly affects product performance. To reduce dimensional variation, it is necessary that an assembly be robust. A robust assembly is less sensitive to input variation from the product and process components, such as incoming parts, subassemblies, fixtures, and welding guns. In order to effectively understand the sensitivity of an assembly to input variation, an appropriate set of metrics must be defined. In this paper, three product-oriented indices, including pattern sensitivity index, component sensitivity index, and station sensitivity index, are defined. These indices can be utilized to measure the variation influence of a pattern, an individual part, and/or component, and components at a particular station to the dimensional quality of a final assembly. Additionally, the relationships among these sensitivity indices are established. Based on these relationships, the ranges of the sensitivity indices are derived. Finally, a case study of a sheet metal assembly is presented and discussed to illustrate the applicability of these metrics.

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