Evaluation of the filtering bleb and its relation to an intrascleral aqueous drainage route after trabeculectomy using ultrasound biomicroscopy

Abstract

Purpose The aim of this study was to evaluate the relationship between filtering bleb parameters (height, extent) and the wideness of the aqueous drainage route beneath the scleral flap using ultrasound biomicroscopy (UBM) in patients who have undergone trabeculectomy with and without mitomycin-C (MMC). Design This was a prospective interventional observation uncontrolled study. Patients and methods A total of 30 patients undergoing 30 glaucoma filtering surgeries were assessed for at least 6 months using UBM to evaluate the bleb reflectivity, the visibility of the route under the scleral flap, the bleb height, and the extent in correlation with the mean intraocular pressure. Patients were divided into two groups: group A included 15 eyes in which trabeculectomy was performed without MMC and group B included 15 eyes in which trabeculectomy was performed with MMC (0.4%) applied for 2 min. Results The reflectivity inside the filtering bleb showed a significant correlation with the maximal width of the aqueous drainage route and the maximal height and the extent of the bleb. Furthermore, the bleb function was significantly associated with its UBM image in eyes trabeculectomized with adjunctive MMC. Conclusion The study concluded that the internal structure of the bleb can be a more sensitive predictor of the outcome of filtering surgery.

Keywords

• bleb dimension
• filtering bleb
• glaucoma
• intraocular pressure
• trabeculectomy
• ultrasound biomicroscopy