Interobserver Variability of the Wuerzburg Bleb Classification Score

Abstract

Abstract: : Purpose: The Wuerzburg bleb classification score (Picht and Grehn, Curr Opin Ophthalmol 9:2–8, 1998) aims for an objective assessment of the development of filtering blebs after trabeculectomy. Purpose of this prospective masked study was to evaluate the interobserver variability in score determination. Methods: The Wuerzburg bleb score is a grading scheme for clinical bleb morphology. It evaluates the following parameters: vascularity, corkscrew vessels and encapsulation are each scored from 0–3 as compared to standard photographs. The presence of microcysts is scored 0 to 3 according to thirds of bleb area bearing cysts and bleb height is estimated as multiple of corneal thickness. The total score can be used to guide treatment decisions in postoperative follow–up. 51 eyes of 49 patients were consecutively examined by three ophthalmologists at different clinical training levels with each observer being unaware of the findings reported by the others. Analysis was performed to determine the variability and agreement between the observers concerning bleb morphology and subsequent therapeutic decisions. Results: Data analysis showed high levels of agreement (defined as complete agreement of all observers or one observer with a difference of +/– 1) for vascularity 94,1%, encapsulation 90,2% and bleb height 90,2%. Slightly lower agreement levels were found for cork screw vessels 76,5% and microcysts 74,5%. The assessment of therapeutical decisions after bleb grading showed a complete agreement of all three observers in 82,4%, in all other cases at least two observers decided for the same therapy. Conclusions: The Wuerzburg bleb classification score allows for standardized filtration bleb analysis with a favourable interobserver variability and consistent therapeutic decision making.

Keywords: wound healing • conjunctiva