Evaluation of early anatomical changes following canaloplasty with anterior segment spectral-domain optical coherence tomography and ultrasound biomicroscopy.

Abstract

To analyse structural changes in conjunctiva, sclera and Schlemm's canal (SC) following canaloplasty with optical coherence tomography (AS-OCT) and ultrasound biomicroscopy (UBM). Fifteen patients undergoing canaloplasty were included in this prospective study. AS-OCT images were acquired pre- and 1, 7, 30 and 90days postoperatively. UBM was performed 3months postoperatively. The surgical site was evaluated for the presence of SC, transscleral filtration, a scleral lake and the visibility of intra-Schlemm-sutures. The height and width of SC were measured at the 3 and 9 o'clock limbus position. After canaloplasty, SC was detectable with AS-OCT in 93% of the patients on day 1. The increase in height was higher than that in width (height: +369%, p=0.0004, width: +152%, p=0.002). IOP was negatively correlated to SC's width 1week postoperatively (r=-0.63, p=0.04) and to SC's height until 3 months (r=-0.66, p=0.02) postoperatively. Using UBM, a reflection of the traction sutures indicated SC's position in all patients. Transscleral filtration was found in all patients using AS-OCT, demonstrating a peak 1week postoperatively. At 3months, a scleral lake could be visualized in 50% and 83% of patients using AS-OCT and UBM, respectively. AS-OCT offers a high resolution for imaging superficial conjunctival areas and SC after canaloplasty, whereas UBM is capable of detecting deeper structures such as scleral lakes or intra-canal-sutures. The results imply a correlation of the dilation of SC with the IOP-lowering effect and an early pronounced transscleral filtration following canaloplasty.