Purpose: To evaluate the long term outcome of 5-Fluorouracil (5-FU) augmented bleb needling revision of failed and failing filtration blebs based on survival analysis and to identify risk factors for failure, indicators for success and complications.
Methods: This was a prospective, interventional case series with survival analysis. 32 eyes of 32 patients underwent bleb needling augmented with 5-FU and were then followed up. Statistical analysis was done to assess the association between study factors and time to failure. Main outcome measures were reduction in IOP (<21 mm of Hg), number of antiglaucoma medications (AGM’s), complications and factors associated with outcome including indicators for success. 
Results: At one year followup 9 (28. 13%) eyes had IOP <21 mmHg without the use of any antiglaucoma medications. 13 eyes (40. 63%) had qualified success with mean IOP <21 mm Hg after 1 or multiple needlings but with the help of one or more AGM’s (1. 2±0. 4). 10 cases (31. 25%) failed and had to undergo repeat Trabeculectomy or shunt surgery. In the cases which achieved overall success, complete and qualified together (n = 22) the baseline IOP pre needling was 26. 7±8. 2 mmHg which was reduced to 13. 6±4. 6 mmHg at the end of the minimum follow up period of 1 year. The median interval between the “index” filtration surgery and the first (or only) needling procedure was 7. 5 months (Range 3 months to 4 years). Overall reduction in mean number of topical AGM’s was from 2. 68±0. 82 to 0. 82±0. 34. Overall cross sectional success rate at 1 year follow up (complete and qualified) was 68. 76%(n=32) and the overall cross-sectional success rate (complete and qualified) at the 3 year follow up period was 66. 91%(n=24) and 65. 82%(n=16) at 5 year follow up. Strong evidence was found for association between pre needling IOP >28 mm of Hg and failure and immediate attainment of low IOP <11 mmHg and longer survival. None of the other proposed factors were identified as having statistically significant effect. 
Conclusions: This long term study shows that bleb needling augmented with 5-FU is a safe and effective method by which a significant number of failed or failing filtration blebs can be rescued. Attaining an immediate reduction in IOP <11 mmHg seems to be a favorable factor with respect to reasonably long-term efficacy.