Anterior Chamber Biometric Parameters Associated With Intraocular Pressure Reduction After Phacoemulsification in Non-Glaucomatous Eyes With Open Angles.

Background: Decreased intra-ocular pressure after cataract surgery has been reported in eyes with and without glaucoma with variable magnitude. It is influenced by the anatomical structure of the anterior chamber. Preoperative evaluation of anterior chamber parameters can help to predict the change in intra-ocular pressure postoperatively.

Objective: The objective of the study is to evaluate intraocular pressure (IOP) change after uneventful phacoemulsification in non-glaucomatous eyes with open angles and its correlation with preoperative anterior chamber parameters measured by anterior segment optical coherence tomography (AS-OCT).

Methods: In this hospital-based prospective observational study, we included consecutive patients without glaucoma and open angles on gonioscopy who had undergone uncomplicated phacoemulsification with intraocular lens implantation (IOL). IOP and anterior chamber biometric parameters were measured preoperatively and compared with parameters obtained three months post-operatively by AS-OCT. The change in IOP and its relation to the parameters, including anterior chamber angle (ACA), anterior chamber depth (ACD), angle opening distance 500 μm anterior to the scleral spur (AOD500), anterior chamber width (ACW), lens vault (LV), and trabecular iris space area (TISA500) were evaluated. The main outcome measure was a change in IOP after phacoemulsification in normal eyes.

Results: Sixty-four eyes of 64 patients were enrolled. The mean patient age was 58.5 ± 9.4 years. The average IOP reduction was 2.43±1.64 mm of Hg from a preoperative mean of 16.77±2.54 mmHg three months after phacoemulsification surgery. The mean AOD500 increased significantly (0.440 ± 0.07 to 0.522 ±0.092) from preoperatively to three months postoperatively (p < 0.001). Preoperative lens vault and preoperative IOP had a strong positive correlation with the change in IOP at three months (r-value = 0.606; p-value <0.001) and (r-value = 0.73; p-value <0.001). There was a significant negative correlation between pre-operative TISA and AOD with change in IOP at three months (r-value = -0.545; p-value <0.001) and (r-value = -0.69; p-value <0.01).

Conclusion:  Phacoemulsification surgery results in IOP reduction in non-glaucomatous eyes. Pre-operative IOP, lens vault, AOD, and TISA were significant predictors for IOP reduction.