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J. A. Hall, D. WuDunn, L. B. Cantor, J. S. Hoop, L. S. Morgan; Correlation Between the Indiana Bleb Appearance Grading Scale (IBAGS) and Late Bleb Leaks. Invest. Ophthalmol. Vis. Sci. 2010;51(13):617.
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To determine whether the IBAGS bleb grading scale can be used to predict which blebs are at high risk for leak.
Bleb photos were taken at 6 and 12 months postoperatively, when under the care of the surgeon, for eyes taking part in a prospective trabeculectomy study1. Each bleb was graded according to morphological criteria as described previously2. Retrospective analysis of the grades and other clinical features including complications, interventions, and duration from date of surgery to detection of leakage was collected from patient medical records. Eyes which did not leak were used as a comparative group.
Eighteen of 115 eyes that underwent limbus-based trabeculectomy developed a bleb leak (>6 months postoperatively). Twelve eyes had bleb photos at 6 and/or 12 months postoperatively, prior to, or at the time of documented leakage (2 cases). Each of these eyes had a bleb vascularity score of V0 (avascular/white with no microcysts visible on slit lamp examination), or V1 (avascular/cystic with microcysts of the conjunctiva visible). Average time to leakage was 27.3 months. Three other eyes, which leaked but did not have photos, were described as avascular between 6 and 9 months postoperatively. Three eyes did not have any bleb descriptions. Cox proportional hazards regression analysis with the IBAGS variables (height, extent, vascularity) did not reveal any to be significant risk factors for bleb leak.
Bleb leak is recognized as the most common late complication of trabeculectomy. Standardized classification of filtering bleb morphology with the IBAGS has proven useful in making bleb evaluation more objective. Avascular blebs are suspected to be more prone to develop late leakage. All eyes in this study which leaked were noted to be avascular. However, among the 52 eyes whose bleb grades were used, only 4 had a score of V2 (mild vascularity) or greater (all in the non-leaking group). The sample size is too small to conclude that this was protective.1 WuDunn D, Cantor LB, Palanca-Capistrano AM, et al. A prospective randomized trial comparing intraoperative 5-fluorouracil vs mitomycin C in primary trabeculectomy. Am J Ophthalmol 2002;134(4):521-8.2 Cantor LB, Mantravadi A and WuDunn D, et al. Morphologic classification of filtering blebs after glaucoma filtration surgery: the Indiana Bleb Appearance Grading Scale, J Glaucoma 2003;12:266-271.
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