Comment on: Factors affecting the early and mid-term success of needling for early failure of filtering bleb.

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Dear Editor, We would like to congratulate Demirok and coworkers[1] for their article, “Factors affecting the early and mid-term success of needling for early failure of filtering bleb.” However, we would like to share our thoughts regarding this study. The authors have classified blebs as cystic, diffuse, flat, and encapsulated, but these terms lack quantification and being a subjective description can lead to wide variations among investigators. Multiple bleb grading systems like the Moorfields Bleb Grading System and Indiana bleb appearance grading scale offer a uniform consensus and good interindividual reproducibility.[2] Characterizing bleb morphology using imaging techniques like anterior segment optical coherence tomography[3] can help in assessment of internal bleb structures, such as bleb wall thickness, size of internal fluid-filled cavities, number of microcysts, scleral flap, subflap space, and the internal ostium, and thus help in deciding if subconjunctival fibrosis is the real cause of failed bleb. Ultrasound biomicroscopy characterization of failed blebs also helps in predicting the outcome of needle revision. In blebs with occluded scleral route, a full bleb revision would work better rather than needling alone.[4] Second, the authors performed the needling within 3 months after trabeculectomy. Since the process of wound modulation posttrabeculectomy involves intense episcleral inflammation, a late needling is likely to result in better pressure profile as shown by Shetty and coworkers.[5] Finally, the concentration and duration of mitomycin-C (MMC) used during trabeculectomy has not been mentioned. Nearly 25% of the subjects in the present study had uveitic glaucoma predisposing them to higher chances of subconjunctival fibrosis. Probably a customized MMC concentration for these cases intra- or postoperatively could have avoided the need for needling. Hence, a definitive conclusion as regard to success of needling in the background of these confounding factors cannot be drawn. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.