Glaucoma Drainage Devices Fixed

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Glaucoma Drainage Devices : 

Glaucoma Drainage Devices Group 10: Justin Galloway Christine Marusich Richard Pace Submitted to Dr. Thomas Boland Clemson University

Glaucoma : 

Glaucoma Second leading cause of blindness in the world Affects over 66.8 million people worldwide Condition of the eye, where the ocular fluid pressure rises to a level that is above 22mmHg [12]

Risk Factors : 

Risk Factors Mutagens Substances known to cause cancer Other Conditions High Blood Pressure Diabetes Steroid Use Race African descendents are three times more likely to develop glaucoma than Caucasians Asians Inuit descendents are forty times more likely to develop closed angle glaucoma than Caucasians

Treatment Options [13] : 

Treatment Options [13] Laser Trabeculoplasty — A laser light is used to open the channels in the Trabecular meshwork Trabeculotomy — A small instrument is inserted into the drainage canal to create an opening through the Trabecular meshwork Trabeculectomy — An opening is made in the channels of the Trabelular meshwork by surgerySeton Insertion — If all other methods fail, an implant is inserted into the eye with a valve, that allows the pressure to be relieved

Trabeculectomy : 

Trabeculectomy Most common surgery used to lower the IOP. Hole is made in the eye. Fluid flows out. Conjunctiva is pulled back. Incision is made in the sclera and part of the trabecular meshwork is removed. Procedure done under local anesthesia. Fluid collects under the conjunctiva where it reabsorbed.

Purpose of Drainage Devices : 

Purpose of Drainage Devices Intended for use in patients who have exhausted all other treatment methods Medication Trabeculectomy Decrease IOP of the eye Draws aqueous humor buildup caused by glaucoma through a drainage tube and away from eye

History of Drainage Devices : 

History of Drainage Devices 1912: The first translimbal glaucoma drainage device is implanted by Zorab ; device used silk thread to drain fluid 1969: Molteno announced that a large surface area is needed to disperse the aqueous beneath the conjunctiva. To this extent, he inserted a short acrylic tube attached to a thin acrylic plate. Most of the operations failed after the first 3-6 months because of plate exposure, tube erosion, and scar formation. 1976: First Molteno implant was introduced consisting of a long silicone tube attached to a large end plate placed 9-10 mm posterior to the limbus . The implant, which offered no resistance to the outflow, often resulted in hypotony , flat ACs , and choroidal effusions. 1992: It was discovered that increasing the surface area of the end plate(s) results in lower IOPs . Baerveldt shunt introduced by George Baerveldt nonvalved silicone tube attached to a large silicone plate with a surface area of 250 mm 2 , 350 mm 2 , or 500 mm 2 1993: Ahmed glaucoma valve (AGV) introduced by Mateen Ahmed 1997: Introduction of the Helies drainage device which uses an artificial meshwork of PTFE fibers 1998: Glaucoma Drainage Devices have been implanted in 2,980 patients 2001: FDA approved the AquaFlow ™ Collagen Glaucoma Drainage Device as an alternative treatment for open-angle glaucoma

Procedure : 

Procedure An incision is made in the conjunctiva and a pocket is created below the iris The implant is placed between the conjunctiva and the sclera and attached to the sclera The drainage tube is trimmed and inserted into the front chamber of the eye, just in below and parallel to the iris

Classifications : 

Classifications Two main classifications of implants Valved Only drains fluid at a certain IOP Valve opens and fluid is drained into a reservoir where it is absorbed by surrounding tissues Non-valved Rely on resistance formed by fibrous capsule or bleb Bleb grows around the implant and creates a space for fluid to drain and be absorbed by surrounding tissue

Materials : 

Materials Medical grade silicone Biocompatable Low tissue response to implantation Odorless Tasteless Resistant to bacterial growth Does not stain or corrode other materials Complies with FDA, ISO, and Tripartite biocompatibility guidelines for medical products High tensile strength (1500psi), good elongation (to 1250%) and flexibiliby Temperature Resistant Stable at a temperature range of -75-500oC Chemical Resistant Resists water, oxidizing chemicals, ammonia, and isopropyl alcohol Picture from:

Materials : 

Materials Polypropylene High flexibility and dimensional stability Low thrombogenicity Poor abrasion resistance Non-toxic High tensile and compression strength Chemically resistant to most alkalis and acids, organic solvents, degreasing agents, and electrolytic attack Degrades in presence of UV light Picture from:

Materials : 

Materials Polytetrafluoroethylene or PTFE Chemically inert to most chemicals including nitric, sulfuric, and phosphoric acids Hydrophobic Highly crystalline and stable Low friction Low wear resistance Inflammation caused by PTFE wear particles Picture from:

Molteno Implants : 

Molteno Implants Developed by Dr. Anthony Molteno in the 1960’s. Increase the surface area of the plate portion. Original device was made out of PMMA. Consisted of a short tube attached to a large plate. Susceptible to erosion. Picture from:

Molteno Implants : 

Molteno Implants Originally placed adjacent to the limbus, intersection of cornea and sclera, and attached to the sclera. Moved to a position a few millimeters away from limbus to allow for better drainage. New design: made of a silicone tube attached to a polypropylene plate. 175mm2 and 230mm2 Double plate. A vicryl tie is often used to prevent hypotony. The tie closes off the drainage tube, preventing an excessive amount of fluid flow. Dissolve in 4-5 weeks

Molteno Implants : 

Molteno Implants Case Study 1 Use in patient with Sturge-Weber syndrome. Initial IOP was 32mmHg in right eye and 37 mmHg in left eye. Normal is 10-20mmHg. Molteno implant placed into both eyes; vicryl tie used. IOP checked 15 years later. Lowered IOP to 15mmHg in both eyes. Needed no post-op treatment. Case Study 2 Young man suffered a trauma to his right eye. Received a trabeculectomy initially. Failed after 5 years. Had an IOP of 45-50mmHg. Received a double plate Molteno implant. IOP lowered to 13-17mmHg. Implant has remained stable after 22 years. No post-op treatment.

Baerveldt Shunt : 

Baerveldt Shunt Created by George Baerveldt in 1992 Abbott Medical Optics Made of medical silicone BG 103-250 BG 101-350 BG 102-350 Pars Plana Non-valved Relies on growth of bleb Increased surface areas allow for better IOP control Patented Bleb Control Mechanism Fenestrations allow tissue to grow through them Control size and height of bleb Minimizes motility disturbances Pictures from:

Ahmed Glaucoma Valve : 

Ahmed Glaucoma Valve Created by Mateen Ahmed in 1993 New World Medical Valved Materials Silicone FP7 FP8 FX1 Extra plate to provide increased drainage Polypropylene S2 S3 B1 Extra plate to provide increased drainage Picture from: Picture from:

Case Study : 

Case Study Patients with Ahmed S2 Glaucoma Valve or Baerveldt 250 mm2 were selected Devices were compared Found that patients with Ahmed S2 had a higher IOP than those with Baerveldt 250mm2 and were also on more medication at the last follow up visit Ahmed S2 also had a higher failure rate but the Baerveldt implant had more complications

[1] : 

[1] Oculieve was created by Dr. Michael Wilcox of Aqueous Biomedical. Lack of Reservoir No Valve Should Eliminate Major complications of most implants Medical Grade Silicone Oculieve [1]

Problems : 

Problems Bleb fails after 2-4 years Fibrous capsule gets too thick Micromovement of implant on the scleral surface initiates the wound healing response Build up of scar tissue increases capsule thickness Interferes with eye motility Prevents aqueous humor from filtering through Hypotony When IOP is too low Usually occurs shortly after surgery because the bleb has not had time to form yet Clogging of the tube with blood or tissue Severe hemorrhaging Extrusion of the shunt Results in removal of implant and reimplantation elsewhere

Works Cited : 

Works Cited Wilcox, Micheal J.. Aqueous Biomedical: products.html (accessed April 16, 2009) Estronaut. GenneX Healthcare Technologies,Inc.: Breast Implants: Health Complications. (accessed April 16, 2009) Jacob, J. T, Burgoyne C. F et Al. Biocompatibility Response to Modified Baerveldt Glaucoma Drains PubMed [online],1998, 42 Anthony C. B. Molteno Ophthalmic Limited: information/glaucoma-drainage-devices/case-studies (accessed April 20, 2009) Shetty, Rajesh. Glaucoma, Drainage Devices. Emedicine [Online] 2008 Burt, Katherine et al. Glaucoma Valves: 2006-108websites/group02glaucoma/history.html (accessed April 22, 2009) Abbott Laboratories: (accessed April 24, 2009) Quigley H. A. Number of people with glaucoma worldwide. British Journal of Ophthalmology, 1996 ;80 Curtis, J. WebMd, Trabeculectomy for glaucoma. filtration-surgery-for-glaucoma (accessed April 16, 2009) Glaucoma Associates of Texas, Trabeculectomy http://www.glaucomaassociates. com/trabeculectomy.html (accessed April 20,2009) Haddrill, M. All about Vision. conditions/glaucoma-surgery.htm (accessed April 20, 2009) Kirkman ,J. Diabetes and Health Issues http://www.diabetesandrelated (accessed April 20, 2009) Gimbel Eye Centre. cataractsandother/glaucoma.html (accessed April 21,2009) Silicone Rubber for Medical Device Applications. Medical Device & Diagnostic Industry Magazine. (accessed April 21, 2009) Polypropylene. Lenntech. (accessed April 21, 2009) Goulet, Robert J. III, et al. Efficacy of the Ahmed S2 Glaucoma Valve Compared with the Baerveldt 250-mm2 Glaucoma Implant. American Academy of Opthalmology. Elsiver, Inc. 2008; 1141-47.

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