Intraocular Pressure Fluctuation Before and After Phacoemulsification in Eyes With Open-Angle Glaucoma

Précis: Although phacoemulsification lowered mean intraocular pressure (IOP) for this entire cohort of open-angle glaucoma eyes, sub-group analysis showed eyes without any medication changes during follow-up period had no change in mean IOP nor fluctuation. Purpose: To examine long-term intraocular pressure (IOP) fluctuation in open-angle glaucoma (OAG) patients pre- and post-phacoemulsification. Patients and Methods: Review of OAG patients who had uncomplicated phacoemulsification. Demographic data, IOP, IOP fluctuation [SD and coefficient of variation (CoV)] and glaucoma medication changes pre and post-phacoemulsification were collected. Analysis included investigation of 4 subgroups based on medication change status. Results: Among 115 eyes meeting inclusion criteria (mean ± SD age 72.5± 9.0 y, pre-operative IOP 15.4±2.8 mmHg, number of medications 2.1±1.1, and visual field mean deviation –5.0±5.1 dB), IOP mean, SD, range, maximum, and minimum were lower after surgery (p≤0.002), while CoV was not different ( P =0.095). Eyes with medication changes pre- but not post-operative (N=27) had improved IOP mean, SD and CoV ( P ≤0.037) while eyes with medication changes post- but not pre-operative (N=33) and changes both pre- and post-operative (N=25) had improved IOP mean but not SD or CoV ( P ≥0.201). Eyes without medication changes had no change in IOP fluctuation ( P ≥0.101). Risk factors associated with an increase in postoperative IOP SD of at least 0.5 mmHg included lower preoperative IOP mean and SD, higher pre-operative IOP maximum, thinner corneal central thickness, postoperative medication changes, and pseudoexfoliation glaucoma ( P ≤0.046). Conclusion: Phacoemulsification decreased mean IOP and SD in the entire cohort, but medication changes before and after surgery significantly influenced IOP SD and CoV. This should be considered in future studies of long-term IOP fluctuation in glaucoma patients.