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

MANAGEMENT

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

HOSKINS 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 deficiencyShields 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.