In Vivo Confocal Microscopy and Biomicroscopy of Filtering Blebs After Trabeculectomy

The aim of this study is to analyze filtering blebs (FBs) after trabeculectomy with in vivo confocal microscopy (IVCM) and slit-lamp biomicroscopy.

IVCM using the Heidelberg Retina Tomograph/Rostock Cornea Module and biomicroscopic examination were performed in 67 FBs in 55 patients 3 months to 30 years postoperatively (mean, 3.2 ± 2.1 y). Although the blebs were evaluated by slit-lamp biomicroscopy, standardized FB classification was used.

Of the patients, 9 were female (16.3%) and 46 were male (83.7%), ranging in age from 32 to 81 (51.5 ± 13.2) years. The absence of vascularization and tortuous vessels and the presence of epithelial microcysts on the bleb were significantly correlated with good bleb function (P=0.001). IVCM findings significantly correlated with good bleb function, including the number of epithelial microcysts (P=0.002), the stromal cysts without capsule (P<0.001), minimal vascularization (P=0.002), and the absence of tortuous conjunctival vessels (P=0.003) and reticular and trabecular bleb patterns (P=0.01 and <0.01, respectively). In contrast, a hyperreflective condensed bleb stroma was significantly associated with bleb failure (P<0.001).

IVCM supports biomicroscopic evaluation as the mainstay for FB analysis and permits diagnostic imaging of FBs to evaluate and follow-up the bleb, differentiation between good and insufficient bleb function, and a microscopic analysis at a cellular level including the structural pattern of the bleb.