Frequency of asymmetric intraocular pressure fluctuations among patients with and without glaucoma

Abstract

Purpose To describe the frequency and magnitude of asymmetric fluctuations of intraocular pressure (IOP) between fellow eyes of glaucoma patients and normal subjects. Design Observational case series. Participants Forty-two subjects without glaucoma and 38 glaucoma patients. Methods By means of retrospective chart review, bilateral IOP measurements were examined over time for subjects without glaucoma and for glaucoma patients whose drug regimens remained unchanged during the period included in the study (at least five readings over at least 1 year). Asymmetric IOP fluctuations of at least 3 mmHg and representing at least a 15% change from baseline were identified. Main outcome measure Occurrence of spontaneous asymmetric IOP fluctuations. Results Twenty-one of 42 subjects without glaucoma exhibited an asymmetric IOP fluctuation between two consecutive visits compared with 24 of 38 glaucoma patients (50% vs. 63.2%, respectively, P = 0.24). Compared with normal subjects, asymmetric IOP fluctuations were observed in 13 of 16 glaucoma patients with prior symmetrical bilateral ocular surgery (50% vs. 81.2%, respectively, P = 0.031), and 11 of 22 ocular surgery-naive glaucoma patients (50% vs. 50%, respectively, P = 1.0). No differences in the magnitudes of the asymmetric IOP fluctuations were noted between groups. Overall, asymmetric IOP fluctuations were observed in 13.7% of follow-up visits among normal subjects versus 16.3% of follow-up visits among glaucoma patients ( P = 0.4). Conclusions Spontaneous asymmetric fluctuations of intraocular pressure between fellow eyes occur commonly in normal subjects and glaucoma patients. The frequency and magnitude of observed spontaneous asymmetric IOP fluctuations between consecutive clinical visits in glaucoma patients are sufficiently large to potentially confound the interpretation of monocular therapeutic drug trials.