Intraocular Pressure Changes after Cataract Surgery in Patients with and without Glaucoma: An Informatics-Based Approach

Abstract

To evaluate changes in intraocular pressure (IOP) after cataract surgery among patients with or without glaucoma using automated extraction of data from electronic health records (EHRs). Retrospective cohort study. Adults who underwent standalone cataract surgery at a single academic center from 2009-2018. Patient information was identified from procedure and billing codes, demographic tables, medication orders, clinical notes, and eye examination fields in the EHR. A previously validated natural language processing pipeline was used to identify laterality of cataract surgery from operative notes and laterality of eye medications from medication orders. Cox proportional hazards modeling evaluated factors associated with the main outcome of sustained postoperative IOP reduction. Sustained post-cataract surgery IOP reduction, measured at 14 months or the last follow-up while using equal or fewer glaucoma medications compared with baseline and without additional glaucoma laser or surgery on the operative eye. The median follow-up for 7574 eyes of 4883 patients who underwent cataract surgery was 244 days. The mean preoperative IOP for all patients was 15.2 mmHg (standard deviation [SD], 3.4 mmHg), which decreased to 14.2 mmHg (SD, 3.0 mmHg) at 12 months after surgery. Patients with IOP of 21.0 mmHg or more showed mean postoperative IOP reduction ranging from -6.2 to -6.9 mmHg. Cataract surgery was more likely to yield sustained IOP reduction for patients with primary open-angle glaucoma (hazard ratio [HR], 1.19; 95% confidence interval, 1.05-1.36) or narrow angles or angle closure (HR, 1.21; 95% confidence interval, 1.08-1.34) compared with patients without glaucoma. Those with a higher baseline IOP were more likely to achieve postoperative IOP reduction (HR, 1.06 per 1-mmHg increase in baseline IOP; 95% confidence interval, 1.05-1.07). Our results suggest that patients with primary open-angle glaucoma or with narrow angles or chronic angle closure were more likely to achieve sustained IOP reduction after cataract surgery. Patients with higher baseline IOP had increasingly higher odds of achieving reduction in IOP. This evidence demonstrates the potential usefulness of a pipeline for automated extraction of ophthalmic surgical outcomes from EHR to answer key clinical questions on a large scale.