Trabeculectomy, Trabeculotomy, Goniotomy and their complications

Trabeculectomy, Trabeculotomy, Goniotomy and their complicationsDR. NAMRATA GUPTA

Incisional Surgery Frequently used for chronic forms of glaucoma in adults Filtering procedure External filtration:Full thickness(Scheie) procedures: Thermal sclerostomy, sclerectomy, Elliotts trephinationGuarded procedures: TrabeculectomyInternal filtration:CyclodialysisTrabecular meshwork disruption:Trabeculotomy ab externoGoniotomy

Open angle glaucoma-No internal flow block and IOP remains too high despite medical therapy, surgery is needed to relieve outflow block2

Trabeculectomy

IntroductionTrabeculectomy, a guarded filteration procedure remains the gold standard for long lasting intraocular pressure reduction in uncontrolled glaucomaPopularized by Cairns (1968)

Mechanism of actionCreation of a fistula at the limbus which allows a direct communication between anterior chamber and subconjunctival space bypassing the trabecular meshwork, schlemm canal and collecting channels

Theories of mechanism

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1, Aqueous flow into cut ends of Schlemm canal (rare); 2, cyclodialysis (if tissue is dissected posterior to scleral spur); 3, filtration through outlet channels in scleral flap; 4, filtration through connective tissue substance of scleral flap; 5, filtration around the margins of the scleral flap.6

Pre-operative evaluation

Indications Intraocular pressure too high to prevent future glaucoma damage and functional visual lossDocumented progression of glaucoma damage at current level of intraocular pressure with treatmentPresumed rapid rate of progression of glaucoma damage without interventionPoor compliance with medical therapy : cost , inconvenience, understanding of diseaseIntolerance to medical therapy due to side effects

Assessment of filtration risk factorsThorough slit lamp evaluation, gonioscopy, record review of past surgeryBest site for filtration determined: PAS, IOL and haptic orientation, aberrant vessels, wound dehiscence, limbal scarring, vitreous prolapseRisk factors for filtration failure: African race, uveitis, aphakia, neovascular glaucoma, prior failed filtration, prolonged anti-glaucoma medicationOcular surface disease: ocular rosacea, blepheritis

Prolonged anti-glaucoma-proliferation of lymphocytes and fibroblasts9

Surgical Technique Perioperative preparations:Intravenous sedation : pediatric, adults unable to co-operateLocal anesthesia: Retro-bulbar injection, peribulbar injection, subtenon, subconjunctival or topical anesthesiaPositioning to maximize exposure to superior globe: protection by lid, no diplopia after PI

Modified small incision trabeculectomy, microtrabeculectomy10

Traction sutures

Superior rectus traction (or bridle) suture

Complications: subconjunctival hemorrhage, conjunctival defects, scleral perforation postoperative ptosis

Globe rotated down and SR grasped with forcep thru conjunctiva 10-15 mm behind limbus11

Traction suturesClear Corneal traction sutures: A 7-0 polyglactin (vicryl) suture is passed through approx. th thickness of superior peripheral cornea(4-5 mm width) 1mm form limbusMay distort the cornea and anterior chamber during surgery

Conjunctival flapGeneral principles: Gentle handling- buttonholing (antifibrotics)Removal of portion of Tenon capsule : source of fibroblast (controversial)

Conjunctival flapTwo types of conjunctival flap:Limbal based conjunctiva flap (LBCF) incision deep in fornix with base at limbus

Fornix based conjunctival flap (FBCF) incision at limbus with base at fornix

Limbal based versus fornix based flap

Anti-metabolite decisionAdjunctive antimetabolites inhibit the natural healing response that may preclude successful filtration surgeryStratified according to patient risk factors

5-FluorouracilPyrimidine analogue antimetaboliteInhibition of thymidylate synthesis, blocks DNA synthesisInhibit fibroblastic proliferationConcentration: Cellulose sponge soaked in 50mg/ml for 5 mins

Edges of conjunctival incision free of 5-fu17

Mitomycin CMore potent than 5-FUAntineoplastic antibiotic isolated from Streptomyces caespitosusSelectively inhibits DNA replication, mitosis and protein synthesis-inhibits proliferation of fibroblast, suppresses vascular ingrowthConcentration: 0.2-0.5 mg/ml for 1-5 mins depending on magnitude of risk factors

Delivering the anti-fibrotic agentCellulose sponge 5 3 mm soaked in antimetabolite is placed under dissected tenons capsule for 5 mins before paracentesis of AC followed by thorough irrigation with BSS

Ring of steelCover largest area possible for more diffuse noncystic bleb and prevent posterior limiting scar (ring of steel)

Moorfields Eye Hospital (More Flow) intra-operative Single Dose Anti- Scarring Regimen 2006 Low Risk Patients (Nothing or intra-operative 5-FU 50mg/ml)No risk factorsTopical medications (beta-blockers/pilocarpine)Afro-CaribeanYouth