In vivo confocal microscopy and ultrasound biomicroscopy study of filtering blebs after trabeculectomy: limbus-based versus fornix-based conjunctival flaps.

Purpose

To evaluate morphological features of filtering blebs after trabeculectomy with limbus-based versus fornix-based conjunctival flaps (LBCF and FBCF, respectively) using in vivo confocal microscopy (IVCM) and ultrasound biomicroscopy (UBM).

Patients and methods: Seventy-five eyes of 62 patients with glaucoma were recruited. Thirty-eight eyes of 31 patients received trabeculectomy with LBCF and 37 eyes of 34 patients received trabeculectomy with FBCF. Successful bleb was defined as postoperative intraocular pressure (IOP) ≤15 mm Hg and IOP reduction ≥20% without antiglaucoma medication. Microcyst number, density of subepithelial connective tissue, and vascularity of subepithelial tissue were evaluated by IVCM. Bleb reflectivity, the route under the scleral flap, bleb height, and height of fluid-filled space were examined by UBM.

Results

On the basis of IOP criteria, 79% (30 of 38 blebs) of the LBCF group and 70% (26 of 37 blebs) of the FBCF group were defined as successful blebs (P=0.28). Compared with the successful FBCF group, the successful LBCF group had a larger microcyst number (P<0.001), lower density of subepithelial connective tissue (P=0.046), greater avascularity of subepithelial tissue (P=0.024), and higher height of fluid-filled space (P=0.017). No morphological differences between LBCF and FBCF groups were found in failed blebs.

Conclusions

Morphological features of successful blebs in IVCM and UBM were different between blebs with LBCF and FBCF. Type of conjunctival flaps should be considered when estimating the bleb function based on bleb morphology examined with these imaging devices.