Interobserver variability of the Würzburg bleb classification score

The Würzburg bleb classification score (WBCS) serves to assess filtering blebs in a standardized fashion. The purpose of this prospective masked agreement study was to evaluate the WBCS interobserver variability.

The WBCS provides a scheme to grade clinical bleb morphology. It evaluates the following parameters: vascularity, corkscrew vessels, encapsulation, microcysts and bleb height. Thus, 113 eyes of 104 consecutive patients at various times after surgery were examined (slit lamp biomicroscopy) by 3 ophthalmologists with each observer being unaware of the findings reported by the others. To calculate the interobserver variability of the WBCS, the interobserver consistency and absolute agreement were determined with an intraclass correlation coefficient (ICC) using a 2-way random model.

The ICC values of a single rater's judgment were: vascularity +0.62, corkscrew vessels +0.67, encapsulation +0.63, bleb height +0.53, microcysts +0.52 and total score +0.74. The ICC values of the mean of all 3 raters were: +0.83 vascularity, +0.86 corkscrew vessels, +0.84 encapsulation, +0.77 bleb height, +0.76 microcysts and +0.90 total score.

The WBCS is a bleb morphology score with high levels of interobserver consistency and absolute agreement in clinical practice.