Ayub Qassim1, Mark J Walland2, John Landers1, Mona Awadalla1, Thi Nguyen1, Jason Loh1, Angela M Schulz3, Bronwyn Ridge1, Anna Galanopoulos4, Ashish Agar5, Alex W Hewitt6, Stuart L Graham3, Paul R Healey7, Robert J Casson8, Jamie E Craig1. 1. Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, South Australia, Australia. 2. Glaucoma Investigation and Research Unit, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia. 3. Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia. 4. South Australian Institute of Ophthalmology, Royal Adelaide Hospital, Adelaide, New South Wales, Australia. 5. Department of Ophthalmology, Prince of Wales Hospital, Sydney, New South Wales, Australia. 6. Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia. 7. Centre for Vision Research, Westmead Institute for Medical Research, University of Sydney, Sydney, New South Wales, Australia. 8. South Australian Institute of Ophthalmology, University of Adelaide, Adelaide, South Australia, Australia.
Abstract
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 < .001) with 59 eyes (34%) achieving at least 3 mmHg reduction. Compared to matched controls, the mean reduction in IOP was 1.75 mmHg (95% confidence interval 1.15-2.33 mmHg; P < .001). Higher preoperative IOP and being on fewer topical glaucoma medications preoperatively were strongly predictive of a larger IOP reduction in a multivariable model. Anterior chamber depth was not associated with IOP reduction. Eyes with preoperative IOP ≥24 mmHg had a mean IOP reduction of 4.03 mmHg with 81% experiencing at least 3 mmHg reduction. Sub-analysis of medication naïve 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.
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 < .001) with 59 eyes (34%) achieving at least 3 mmHg reduction. Compared to matched controls, the mean reduction in IOP was 1.75 mmHg (95% confidence interval 1.15-2.33 mmHg; P < .001). Higher preoperative IOP and being on fewer topical glaucoma medications preoperatively were strongly predictive of a larger IOP reduction in a multivariable model. Anterior chamber depth was not associated with IOP reduction. Eyes with preoperative IOP ≥24 mmHg had a mean IOP reduction of 4.03 mmHg with 81% experiencing at least 3 mmHg reduction. Sub-analysis of medication naïve 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.