Ultrasound biomicroscopy of intrascleral lake after viscocanalostomy and cataract surgery

Purpose: To assess anatomic changes at the sclerectomy site after combined viscocanalostomy and cataract surgery associated with POAG or OH and cataract. Methods: In a prospective, noncomparative, longitudinal study, we performed ultrasound biomicroscopy (UBM) of the sclerectomy site in 84 eyes at 3, 6, and 12 months after the surgery. Four parameters in UBM findings (area, radial longitudinal length, height of intrascleral space, and meridional length of window) were measured and the IOP level, the number of antiglaucoma medications, and bleb formation were observed for 12 months. Results: Intraocular pressure decreased from 19.8 +/- 3.5 (+/- SD) mm Hg preoperatively to 15.5 +/- 3.0 mm Hg 12 months postoperatively (P < 0.0001). Blebs were formed in 2 of 84 eyes (2.4%) at 1 month, and 1 of 84 eyes (1.2%) after 3 months. The IOP decreased at 3, 6, and 12 months postoperatively by 5.8, 4.8, and 4.3 mm Hg, respectively (P = 0.0016). A significant difference was observed between 3 months and 12 months in area (0.17 and 0.13 mm 2, respectively, P = 0.0127 using the Bonferroni/Dunn test), longitudinal length (0.89 and 0.72 mm, P = 0.0059), and height (0.21 and 0.15 mm, P < 0.0001), but not in meridional length (0.41 and 0.33 mm). The lake was present in 66.7% of cases at 12 months. Conclusion: Combined viscocanalostomy and cataract surgery lowered IOP without bleb formation. Postoperatively, the size of the lake and IOP decreased, suggesting parallel reduction of the two. The lake was undetected ultrasonographically in one third of the cases 1 year postoperatively.