The effects of phacoemulsification on intraocular pressure and ultrasound biomicroscopic image of filtering bleb in eyes with cataract and functioning filtering blebs

Abstract

To evaluate the effects of phacoemulsification on intraocular pressure (IOP) and ultrasound biomicroscope (UBM) images of filtering bleb in eyes with cataract and a previous functioning filtering bleb. The IOPs and UBM images of filtering bleb of 24 patients (27 eyes) who underwent phacoemulsification after successful trabeculectomy were recorded at each follow-up examination and at the 12 months after phacoemulsification, respectively. Preoperative IOP and two parameters of the UBM images, including visibility of a route under the scleral flap and reflectivity inside the bleb were evaluated for an association with postoperative success rate using Kaplan-Meier survival analysis. The mean IOP increased 5.50, 3.85, 3.11, 3.05, 2.79, and 2.58 mmHg after 1 day, 1 week, 1, 3, 6, and 12 months, and it was significantly higher than the preoperative IOP (P=0.000, 0.000, 0.000, 0.000, 0.000, and 0.000 respectively). There was no statistically significant difference in visibility of the route under the scleral flap and reflectivity inside the bleb before and after phacoemulsification (P=0.398, 0.096). An IOP greater than 10 mmHg, a bleb with an invisible route under the scleral flap and stronger intrableb reflectivity before phacoemulsification were associated with postoperative antiglaucomatous failure (P=0.025, 0.000, and 0.000 respectively). Phacoemulsification significantly increased IOP, but had less effect on intrableb features in UBM image. Eyes with higher IOP, invisible route under scleral flap and stronger intrableb reflectivity in UBM image before phacoemulsification had greater postoperative antiglaucomatous failure.