Video report - April 2002

Surgical revision of leaking filtering blebs with an autologous conjunctival graft

K Taherian, A Azuara-Blanco

Aberdeen Royal Infirmary, Foresterhill, Aberdeen, United Kingdom

Correspondence to: Dr. A.A. Blanco, Consultant Ophthalmologist, Eye Clinic, Aberdeen Royal Infirmary, Foresterhill, Aberdeen AB25 2ZN

Accepted for publication: 1 December 2001

Surgical revision of a leaking filtering bleb, by removal of conjunctival epithelium, and placement of an autologous conjunctival graft by suturing it over the bleb wall with 10-0 nylon suture.

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Introduction

Bleb leak developing years after filtration surgery is one of its most challenging complications. Bleb leak may be associated with severe hypotony and increases the risk of endophthalmitis. Spontaneous late bleb leaks are more frequent in avascular, thin blebs, which occur more frequently when antimetabolites are used in the filtering procedure and after full thickness filtering procedures.

In the case demonstrated in this video, a 75-year-old female was referred with persistent bleb leak of eight months duration in her left eye. She had undergone a full thickness filtering procedure in 1970. On presentation, there was a mildly elevated, thin-walled avascular bleb. The intraocular pressure was 5 mmHg and best-corrected visual acuity was 6/36. Treatment with a large (18 mm) bandage contact lens and autologous blood injection failed to seal the leak. The patient underwent surgical revision of the leaking bleb.

Surgical Technique

Fluorescein drops are used to confirm the exact location of the bleb leak. A 7-0 silk corneal traction suture is used. A conjunctival incision is made surrounding the ischaemic and thin-walled bleb, making the incision in healthy, vascularised conjunctiva. The bleb and superior limbus are denuded of conjunctival and corneal epithelium by blade debridement and mild wet-field cautery to allow short- and long-term adherence of the flap tissue.

Posterior dissection of the conjunctiva is done with Wescott scissors. Fresh conjunctiva posterior to the bleb is mobilized anteriorly to cover the previous filtration site.¹ However, this option may not be technically possible, and a free conjunctival graft may need to be used.^1-3

The size of the area to be covered is measured with calipers. An inferior corneal traction suture is placed. The diameter of the graft is oversized by 2 mm to facilitate the surgical closure, and a marking pen is used to facilitate the location of the incision. Superficial conjunctival dissection is done, excluding the Tenon�s capsule from the graft. Pre-placed conjunctival sutures (10-0 nylon) help to displace the conjunctival tissue maintaining the epithelial surface up.

The conjunctival graft is sutured watertight with 10-0 nylon over the peripheral cornea and surrounding conjunctiva. A bandage contact lens is then used.

In this case no leak was noted after surgery. Six months later, the IOP was 11 mmHg, and her visual acuity was 6/9.

Comment

Therapeutic modalities to treat leaking blebs include the use of pressure patching, bandage contact lens, Simmons� shell, symblepharon ring, fibrin tissue glue injection of autologous blood, cryopexy, argon laser, thermal Nd:YAG laser and surgical revision.¹

When other simpler methods have failed, and the bleb leak is persistent and complicated with hypotony, surgical intervention is indicated. Due to the friable nature of the conjunctiva in long-established filtering blebs, it is not possible to close the defect directly with sutures. Therefore conjunctival flaps or grafts are utilized, as in this case. It is important to attempt to save the established initial filtration site. The current surgical technique, removing the conjunctival epithelium and placing a free conjunctival graft conjunctiva over it, was helpful to treat the bleb leak and maintain the function of the filtering bleb. This technique should be considered when conjunctival advancement is not technically possible.

References

1. Azuara-Blanco A, Katz LJ. Dysfunctional filtering blebs. Surv Ophthalmol 1998;43:93-126.
2. Harris LD, Yang G, Feldman RM, et al. Autologous conjunctival resurfacing of leaking filtering blebs. Ophthalmology 2000;107:1675-1680.
3. Wadhwani RA, Bellows AR, Hutchinson BT. Surgical repair of leaking filtering blebs. Ophthalmology 2000;107:1681-1687.