Late Failure of Filtering Bleb

Late failure of filtration has several causes that range from blockage of the internal ostium to remodeling of the filtering bleb to frank scarring of the bleb. Identifying the cause makes management clear and likely to be successful. Bleb remodeling occurs within the first 3-4 months following filtration surgery and can often be managed conservatively as it may be transient. Scarring of the episclera with loss of bleb function may occur anytime from weeks to months or even years after the initial surgery. Needling using loupes or at the slit lamp is often successful in this situation and is a worthwhile in-office treatment to try. Sometimes, operative revision of the filtration bleb or repeat filtration at an alternate site is necessary if needling fails.