Ultrasound biomicroscopy after canaloplasty: clinical study with two different units

Canaloplasty is a recent non penetrating glaucoma surgical procedure where Schlemm's canal is dilated and trabecular meshwork distended by tensioning polypropylene suture. The aim of this study was to visualize the iridocorneal angle after the canaloplasty procedure by means of two different ultrasound biomicroscopy (UBM) units. Ten eyes of nine patients with primary open angle glaucoma (average age 62 years) underwent canaloplasty (six eyes) or canaloplasty combined with phacoemulsification and in-the-bag intraocular lens implantation (4 eyes). Both 50 MHz (Paradigm P45) and 80 MHz (i-UltraSound) systems were used. All procedures were performed by the same surgeon. UBM examination was performed 3 to 12 (mean 7 +/- 3.1) months after surgery. No, mild and good trabecular meshwork distension by suture tensioning was graded as 0, 1 and 2 according to the higher resolution 80 MHz images. Both ultrasound systems could show intrascleral lake and trabecular meshwork distension, which was graded as 0, 1 and 2 in 10%, 30% and 60% of eyes, respectively. Schlemm's canal could be imaged with the 80 MHz transducer only. The overall qualified success of canaloplasty (80%) was apparently correlated with suture tensioning (r=0.64). In our experience, after canaloplasty the 80 MHz but also 50 MHz technology can show trabecular meshwork distension. A greater number of eyes are needed to assess the correlation between intraocular pressure decrease and suture tensioning.