Abstract

FR.11.05

A new instrument for failed filtering bleb revision surgery ab interno as an alternative to the needling procedure

Schmitz K., Niederdräing N., Meller D., Steuhl K. P.
University Eye Hospital Essen

Objective: In 20-50% of all cases of glaucoma filtering procedures, bleb failure occurs during the postoperative course due to scarring of subconjunctival or scleral tissue. The established procedure for revision of this situation is needling of the scar tissue with a subconjunctivally advanced cannula, which may also be used for lifting the scleral flap. This procedure may cause substantial trauma to the conjunctiva with the risk of intraoperative hemorrhage and postoperative re-scarring. Lifting of the scleral flap is a poorly controlled measure. Some eyes may require repeated needlings to achieve the desired pressure lowering filtration flow.
Methods: We have developed a new surgical instrument with an outer shape similar to that of a cyclodialysis spatula. The instrument is introduced into the anterior chamber via a paracentesis opposite to the trephination site. After passage through the anterior chamber the tip of the instrument is introduced into the trephination site and under the scleral flap. An advancable knife at the tip of the instrument can be used to dissect scleral and subconjunctival scars. The new instrument was used on 15 patients with failed filtering bleb for bleb revision surgery ab interno.
Results: A free passage of aqueous from the anterior chamber to the reopened subconjunctival space could be achieved without additional needling from the outside in 14 of 15 patients. In 3 of 15 patients postoperative conjunctival hemorrhage and in 2 of 15 patients postoperative hyphema were observed. An adequate pressure lowering effect without any further measures during a postoperative follow-up of at least 3 months could be observed in 13 of 15 cases.
Conclusions: The new instrument is a useful tool for bleb revision ab interno with high efficacy and a low rate of complications. Further studies on a larger number of patients need to be carried out to compare the results of the described bleb revision ab interno with conventional needling procedures by puncture of the subconjunctival space from the outside.

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