Published on March 12, 2014
MANAGING THE FAILING BLEB • RECOGNISE FAILURE • IDENTIFY THE CAUSE • DEAL WITH HIGH IOP • RESTORE BLEB FUNCTION
Risk factors for failing bleb • Young age • Males • Black race • Congenital and juvenile glaucoma • Subconjunctival hemorrhage • Excessive inflammation – Long-term topical glaucoma therapy – Traumatic glaucoma – NVG • Reaction to sutures
HISTOLOGY • EPITHELIUM – Similar in both functioning and failed blebs • SUBEPITHELIAL CONNECTIVE TISSUE – Loosely arranged tissue with clear spaces – Dense collagenous tissue with no spaces
Elevated IOP with a deep anterior chamber Typical failing bleb • Low to flat • Heavily vascularized • No microcysts • 6.9 to 36 % • Tight sutures • Internal block • Early, aggressive intervention required Tenon’s cyst • Highly elevated • Smooth-domed • Large vessels but intervening avascular spaces, no microcysts • Patent sclerostomy • 3.6% to 28% • Within the first 2 months • Most resolve on conservative management
Most important step : recognising its presence • Preceded by a gradual increase in IOP • Change in the bleb's appearance – Less diffuse – Avascular (large vessels but intervening avascular spaces) – Opalescent – Flat / very elevated, smooth-domed – Surrounding fibrotic vascular ring – Loss of microcysts (fluorescein) • Pressure does not decreases after massaging
SEEK OUT THE CAUSE • BLOCK OF INTERNAL OSTIUM • EXTERNAL BLOCK (most common)
• INTERNAL BLOCK – Iris – Ciliary body – Vitreous – Blood clot – Fibrin • Gonioscopic evaluation • EXTERNAL BLOCK – Tenon’s cyst – Episcleral scarring • Careful slit lamp evaluation
RAISED IOP • Digital ocular pressure – steady pressure over the inferior sclera, through the eyelids for 10 to 15 seconds – intermittent – taught to the patient • Medical – Topical (avoid PG anlogues, Brimonidine) – Systemic
• Frequent anti-inflammatory therapy • Laser suture lysis – first 3 wks without antimetabolites; 8 wks with antimetabolites – argon or green light laser – Nd YAG laser. Ruptures conjunctival and episcleral blood vessels – 400 mW, 0.01 seconds and 50 μm – one suture at a time, if no effect within 1 hour, second suture lysis or removal may be considered RESTORING BLEB FUNCTION
• Without magnification – Edge of a four-mirror gonioprism – Hoskins laser suture lens • High-magnification suture lysis contact lenses – Mandlekorn lens – Blumenthal lens – Ritch lens
• Releasable sutures • Topical mitomycin C (0.02% QID for 2 weeks) • Bleb revision BLOCKED INTERNAL OSTIUM • Intracameral tissue plasminogen activator (blocked internal ostium; blood or fibrin clot ) – 6 to 12.5 µg – Frozen (TPA) - 25 g/ 0.1ml is diluted with 0.9 % NaCl • Low-energy argon laser therapy / Nd:YAG laser disruption (retract the tissue) – Iris – Vitreous • Internal bleb revision
EXTERNAL BLEB REVISION • Tenon’s cyst / episcleral scarring unresponsive to conservative management • First described by Ferrer1 in 1941 – conjunctival dialysis – incising the scar tissue – conjunctiva from the sclera with a spatula • Pederson and Smith2 – needling encapsulated blebs – 69% success 1.Ferrer H. Conjunctival dialysis in the treatment of glaucoma recurrent after sclerectomy. Am J Ophthalmol. 1941;24:788- 790. 2.Pederson JE, Smith SG. Surgical management of encapsulated filtering blebs. Ophthalmology. 1985;92:955-958.
• Ewing and Stamper3 – 5-fluorouracil (5-FU) in bleb needle revisions – Postop subconjunctival injections – 91.6% success rate – 63.6% : adjunctive medications • Shin et al4 – single injections of 5-FU during needling – 80% success rate – 79% : adjunctive medications 3.Ewing RH, Stamper RL. Needle revision with and without 5-FU for the treatment of failed filtering blebs.Am J Ophthalmol. 1990;110:254-259. 4. Shin DH, Juzych MS, Khatana AK, et al. Needling revision of failed filtering blebs with adjunctive 5-fluorouracil. Ophthalmic Surg. 1993;24:242-248.
• Mardelli et al.5 in 1996, – Slit-lamp procedure – Mitomycin C (MMC) injections – 92% success rate 5.Mardelli PG, Lederer CM Jr, Murray PL, et al. Slit-lamp needle revision of failed filtering blebs using mitomycin C. Ophthalmology. 1996;103:1946-1955.
• Risk factors for failed needling – Pre procedure IOP > 30 mm Hg – Trabeculectomy without MMC – Immediate post procedure IOP >10 mm Hg – After 4 months of trabeculectomy6 6.Gutierrez-Ortiz C, Cabarga C, Teus MA. Prospective evaluation of preoperative factors associated with successful mitomycin C needling of failed filtration blebs. J Glaucoma. 2006;15:98-102.
TECHNIQUE FOR NEEDLING • Goal : – Increase the permeability of the bleb's wall – Produce a more diffuse, better functioning bleb. • Slit lamp / Operation theatre – Informed consent – Antibiotic drops – Clean-drape if in OT – Topical anaesthetic – Lid speculum
• 25G needle (sturdier) • 5 to 10 mm temporal from the bleb site • Posteriorly directed, bevel up, tangential to sclera • Advanced in the bleb with a twisting motion • Subconjunctival fibrosis cut with firm back & forth , side to side motions till eye softens • Can enter AC (pseudophakes; flat bleb) • Avoid conjunctival buttonhole
• Can be accompanied with – Subconjunctival injection of MMC (0.1 mL 0.04 mg/mL) – 5-FU (5mg in 0.1 mL lignocaine) given • 180 degrees away from the bleb • 15 to 50 mg in 3-10 injection over 3 weeks • Antibiotic/steroid drops for 2-3 weeks • Digital massage
COMPLICATIONS • HYPOTONY – Buttonhole – Aggressive neeedling • BLEBITIS • ENDOPHTHALMITIS • EPITHELIAL TOXICITY (5-FU) • ENDOTHELIAL TOXICITY (MMC)
• MMC drops comparable to 5-FU injections in terms of – IOP, bleb appearance, – success rate, (68.4% MMC, 77.8% 5-FU) – number of glaucoma medications, – visual outcome, – overall complications Pakravan M, Miraftabi A, Yazdani S.Topical Mitomycin-C versus Subconjunctival 5- Fluorouracil for Management of Bleb Failure. J Ophthalmic Vis Res. 2011 Apr;6(2):78-86.
TOPICAL MMC • SIDE EFFECTS – Local irritation, hyperaemia, – Epiphora (Punctal stenosis), – Allergy, – Keratoconjunctivitis – Corneal abrasion (superficial punctate keratitis) – Cataract, – Persisting keratoconjunctivitis, – Limbal stem cell deficiency Shields CL, Naseripour M, Shields JA. Topical mitomycin C for extensive, recurrent conjunctival-corneal squamous cell carcinoma. Am J Ophthalmol 2002;133:601–6. Fucht-Pery J, Rozenman Y. Mitomycin C therapy for corneal intraepithelial neoplasia. Am J Ophthalmol1994;117:164–8. Song JS, Kim JH, Yang M, et al. Mitomycin-C concentration in cornea and aqueous humor and apoptosis in the stroma after mitomycin-C application. Cornea 2007;26:461–
• Subconjunctival 5-FU application more effective therapy than bevacizumab for needling procedures in failed trabeculectomy blebs. Simsek T1, Cankaya AB, Elgin U. Comparison of needle revision with subconjunctival bevacizumab and 5-fluorouracil injection of failed trabeculectomy blebs. J Ocul Pharmacol Ther. 2012 Oct;28(5):542-6.
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