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Editors Selection IGR 11-2

Filtering Blebs: Bleb revisions

Comment by Malik Kahook on:

24192 Outcomes of surgical bleb revision for complications of trabeculectomy, Radhakrishnan S; Quigley HA; Jampel HD et al., Ophthalmology, 2009; 116: 1713-1718

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Trabeculectomy remains the gold standard surgical procedure for glaucoma refractory to medical therapy and/or laser trabeculoplasty. While very effective at lowering intraocular pressure, post-trabeculectomy complications such as hypotony, wound leaks and bleb-associated dysesthesia are not uncommon. Radhakrishnan et al. (1316) recently performed a retrospective review to report outcomes in patients undergoing surgical intervention for bleb related complications. Success was defined as eliminating the primary indication for surgery without need for further IOP lowering surgery or development of complications. The mean time between trabeculectomy and surgical revision was 3.5 ± 3.7 years. The reported success rate was 63% (112/177 Eyes). Successful outcomes in eyes with bleb leaks (65%, n = 98) and hypotony (63%; n = 51) were slightly higher than for those with dysesthesia (57%, n = 28). Overall cumulative success rates after bleb revision, by Kaplan-Meier analysis, were 80% at one year, decreasing to 41% at ten years. IOP and visual acuity improved significantly in eyes with hypotony and bleb leaks. The authors conclude, 'Surgical bleb revision often provides successful resolution of bleb-related complications.' Limitations of this report are present largely due to the retrospective nature of the study design. In many instances, critical definitions were not concrete and left up to the treating physician to decide (definition of hypotony for example). Eighty-three eyes were excluded from the analysis including those having various issues with data collection, short follow-up and patients undergoing 'nonsurgical' management of bleb related issues. It is unclear how data from these patients might have influenced final analysis. A major variable, which was not accounted for in this study, is that different surgeons did the procedures with inherent differences in surgical technique and postoperative follow-up.

Revision of blebs is generally successful with good outcomes

While the authors state that this makes their findings 'more generalizable' this fact also makes subsequent data analysis difficult to implement to any given practice or to influence surgeons with any given surgical techniques.

While retrospective studies have inherent limitations due to their design, there are many important points that can be gleaned from this report. It does appear that, overall, revision of blebs in patients similar to those reported by the authors is generally successful with good outcomes. An interesting finding that requires further study is that patients with glaucoma other than primary open-angle glaucoma were twice as likely to have failed bleb revision. This fact might influence how these patients are approached and can potentially affect clinical decision-making. Finally, it is encouraging to note that patients with hypotony and decreased vision did have improvement in vision after intervention. This fact was qualified by the authors' own admission that strict data on pre and postoperative vision was lacking including data on refractive status. A prospective study with long-term follow up and defined surgical interventions would be desirable at this point and can build upon the data published by Radhakrishnan et al. and others.

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