Trabeculectomy is an eye operation in which a drainage fistula is created in the wall of the eye to reduce intraocular pressure, which is the goal of treating glaucoma. The fluid drained from the eye forms a blister-like reservoir called "filtering bleb" where the fluid from the eye is then absorbed. Extensive scarring of the subconjunctival tissue leads to failure of the operation, therefore, drugs that inhibit cell growth and scar formation are used. Sometimes these drugs lead to thin walled and avascular filtering blebs, which are prone to leaks and infections. Such late-onset filtering blebs and associated infections are a dangerous and common complication after filtering glaucoma surgery. For late-onset bleb leaks, various treatments ranging from antibiotic eye drops to surgical closure of the leak have been suggested. The aim of this review was to compare any interventions to treat bleb leaks with conservative treatment and different interventions with each other. The literature search for this review identified only one randomised controlled trial (RCT) that compared two surgical techniques covering the leaking filtering bleb with different types of tissue. The two surgical techniques were (1) conjunctival advancement whereby the conjunctiva (tissue covering the sclera) is dissected and mobilised forward to cover the leaking area, and (2) amniotic membrane transplant. The amniotic membrane is a thin, transparent tissue covering the foetus in the womb that is obtained after birth.

Based on these findings it cannot be decided which intervention for filtering bleb leaks is the best, and whether an intervention is necessary at all. The authors' opinion is that in persistent bleb leaks, and those associated with sight threatening conditions such as hypotony (i.e. very low pressure in the eye), conjunctival advancement is the most promising procedure.