Abstract
Purpose:
To investigate anterior segment parameters and biometric factors associated with intraocular pressure (IOP) lowering after uneventful phacoemulsification
Methods:
This prospective, single centre study conducted in University Malaya Medical Centre, Kuala Lumpur between July, 2013 and February, 2014. All participants underwent uneventful phacoemulsification with foldable intraocular lens implantation. Only the right eye was used for analysis if both eyes were eligible. IOP measurement, gonioscopy and anterior segment optical coherence tomography (ASOCT; Carl Zeiss, Meditec, Dublin, CA) measurements were performed preoperatively and postoperatively at 1 week and 1 month. Customised software (Zhongshan Angle Assesment Programme -ZAAP) was used to measure various anterior chamber parameters including central corneal thickness (CCT), anterior chamber depth (ACD), anterior chamber width (ACW), angle opening distance at 500 microns(AOD 500) anterior to the scleral spur and lens vault (LV). A-scan biometry (US800, Nidek Co Ltd, Tokyo, Japan) was used to measure axial length (AL) and lens thickness (LT) and and calculate lens position(LP) and relative lens position (RLP). Univariate and multivariate analysis were performed to determine the predictive factors of IOP lowering after phacoemulsification.
Results:
Eighty-six eyes from 86 patients were included in the study. The mean IOP reduced significantly (16.24 ± 2.4 mmHg to 14.1 ± 2.6 mmHg at 1 week and 14.4 ± 2.3 mmHg at 1 month) (p < 0.001 for both) after phacoemulsification. The AOD500 increased significantly (0.46 ± 0.25 mm to 0.69 ± 0.17 mm at 1 week and 0.72 ± 0.18 mm at 1 month) after surgery(p<0.001 for both). Anterior chamber depth increased significantly (2.89 ± 0.3 mm to 4.05 ± 0.35 mm at i week and 4.11 ± 0.30 mm) also (p<0.001). Reduction in IOP correlated with the increase in AOD500 (r = 0.24, p = 0.035) at 1 month after surgery. In the multiple regression model, axial length was the only factor which correlated with percentage change in IOP (standardised beta=0.232, p=0.01) after adjusting for age and CCT.
Conclusions:
This hospital based study shows that a higher axial length is independent predictor of intraocular pressure lowering post uncomplicated phacoemusification.