In the name of God

Glaucoma Drainage Devices S.M.Shahshahan M.D Feb 2010

History Early 20 th Century Use of foreign material Setons or stents in the true sense Silk thread, horse hair, gold, platinum, tantalum, glass, PMMA, silicone, gelfilm and acrylic The outcomes were generally poor

Glaucoma Drainage Devices, GDDs The pioneering work by Molteno is the basis of all modern tube shunt implants. Molteno revised his early tube design for a larger and more posteriorly fixated device.

Glaucoma Drainage Devices, GDDs A silicone tube and posterior encapsulation are common to all procedures. Differences include use of flow restricting mechanisms, composition, shape and size. Provide a free channel for aqueous outflow

Indications NVG Uveitis ICE syndrome Epithelial ingrowth

Indications (coun..) Severe anterior segment abnormalities Failed Trabx High risk for Trabx complications Hx of bleb infections

Indications (coun...) Severe conj scarring Aphakic and Pseudophakic Intractable developmental glaucomas With V-R procedures Contact lens use

Filtration in GDDs The filtration site is placed posteriorly near the equator The episcleral explant stimulates fibrovascular proliferation (several weeks) Silicone induces less inflammation than polypropylene

Filtration in GDDs Larger and thinner-walled capsules yield lower IOP However there is an upper limit for bleb surface area Very large blebs have great surface tension in the wall Very large areas may be detrimental for bleb function and ocular motility

Glaucoma drainage devices Non-restricted Molteno Baerveldt Schocket Restricted Ahmed Krupin Joseph White Optimed ExPRESS

Valve mechanism properties Opening and closing pressures for valved shunts: 10 and 8 mmHg for AGV 11 and 9 mmHg for Krupin The AGV was the only valve shunt with variable resistance according to flow rate Highest resistance with Optimed

Surgical technique

ANESTHESIA GA or local The choice depends on patient ’ s general and ocular conditions Also dependent on surgeon ’ s experience and preference

Basic surgical steps Peritomy (fornix or limbus based) MMC application ? Valve priming or tube ligature Plate fixation (nonabsorbable material) #23 needle through limbus (1 to 2-mm intrascleral tunnel), parallel to iris Tube shortened obliquely About 2-3 mm is in the anterior chamber, bevel facing anteriorly Tube fixation with suture and coverage with patch graft Conj closure

Choice of quadrant Site and quadrant of the operation depends on conj quality, implant size design and type, previous ocular procedures. The S-N is best left avoided Other quadrants each have their pros and cons Beware of cosmesis in I-T shunts

Distance from optic nerve Greatest: Molteno Closest: AGV Generally: 8-10mm posterior to limbus

Tube implantation site Anterior chamber (routine) Pars plana (PK, complete vitx, disorganized anterior segment) Ciliary sulcus (extensive PAS, ACIOL)

Patch graft Sclera, fascia lata, or pericardium. Risk of HIV transmission with sclera ? Pericardium is commercially prepared and packaged, sterility is superior to sclera. Other potentially acceptable tissues are amniotic membrane or dura. Cornea allows laser manipulation of sutures; may be superior cosmetically. All materials are comparable in terms of durability and melting.

Valved versus nonvalved GDDs All valved shunts should be primed by irrigation of fluid through the tube. Nonvalved devices need extra steps to prevent excessive filtration and hypotony

ADJUSTING TUBE FLOW 4-0 nylon suture is inserted into the tube A 6-0 Vicryl suture is tied externally around the tube to allow controlled filtration. An alternative approach is total occlusion of flow with the external ligature. Venting foots are made in the tube proximal to the external ligature. These vents are created with a sharp microblade and allow fluid flow at high intraocular pressures until the external ligature dissolves or is cut.

Two-stage approach The plate is placed in the subconjunctival region and the tube is left in the subconjunctival space. Anterior chamber entry is deferred until a later date. After subconjunctival healing occurs, the tube is placed in the anterior chamber.

Postoperative medications Topical steroids Cycloplegics Antibiotic

Early Postoperative Complications

EARLY COMPLICATIONS Elevated Intraocular Pressure valve malfunction tube occlusion suprachoroidal hemorrhage tube retraction

TUBE OCCLUSION Iris incarceration (cycloplegia, laser peripheral iridectomy or iridoplasty, surgical intervention) Intraluminal fibrin or blood clot (observation, laser, tPA, irrigation) Vitreous plugging (Nd:YAG laser vitreolysis or vitrectomy)

AQUEOUS MISDIRECTION Management as in other scenarios with malignant glaucoma Redirection of the tube from the anterior chamber into the vitreal cavity through the pars plana

SUPRACHOROIDAL HEMORRHAGE A grave complication in high risk eyes Risk factors and management as in other conditions

RETRACTED TUBE confirm with gonioscopy. If the tube is too short, move the plate closer to the limbus or place an extender sleeve tube with a larger diameter over the preexisting tube to lengthen it. (tube extender commercially available for AGV)

ضمن عرض پوزش بدلیل حجم بالای LECTUER ادامه اسلایدها امکان پذیر نمیباشد در صورت نیاز به ادامه لطفا به واحد سمعی و بصری مرکز آموزشی درمانی فیض مراجعه و یا با شماره تلفن داخلی 392 تماس حاصل نمائید با تشکر