Effect of phacoemulsification cataract surgery on intraocular pressure in early glaucoma: A prospective multi‐site study

IMPORTANCE: Cataract and primary open-angle glaucoma (POAG) commonly co-exist, and cataract surgery is thought to reduce intraocular pressure (IOP), the major modifiable risk factor of POAG. BACKGROUND: Previous studies exploring the effect of cataract surgery on IOP are limited by retrospective design, lack of a control group, medication use and washout and loss to follow up. DESIGN: Prospective, multicentre, matched case-control Australian study. PARTICIPANTS: 171 eyes of 108 POAG patients who underwent cataract surgery, matched to 171 control eyes. METHODS: Serial longitudinal IOP measurements were compared before and after cataract surgery, and relative to the controls. A mixed-effect model was used for the longitudinal data. MAIN OUTCOME MEASURES: Change in IOP. RESULTS: The mean follow-up time was 4.8 (1.4) years. Cataract surgery reduced mean IOP by 2.22 mmHg (95% confidence interval: 1.93-2.52 mmHg, P /=24 mmHg had a mean IOP reduction of 4.03 mmHg with 81% experiencing at least 3 mmHg reduction. Sub-analysis of medication naive and pseudoexfoliation patients showed similar results. CONCLUSIONS AND RELEVANCE: Cataract surgery has a confirmed effect in reducing IOP in a "real world" setting of early glaucoma patients.