Effects of ambient temperature on intraocular pressure in patients with stable primary open-angle glaucoma under medical treatment

Aims To investigate the effects of ambient temperature on intraocular pressure (IOP) in patients with stable primary open-angle glaucoma (POAG) under medical treatment. Methods This retrospective study analysed longitudinal IOP data via Goldmann applanation tonometer of POAG patients treated at the Kyoto Prefectural University of Medicine Hospital from 2012 to 2023. Inclusion criteria were no history of ophthalmic surgeries, no change in medications, age ≥40 years and ≥3 visits/year for ≥3 years. Data were analysed using a linear mixed-effects model with individual eyes as the random effect. Fixed effects included age, mean deviation of Humphrey Visual Field Perimetry, corneal curvature radius, central corneal thickness (CCT), axial length, mean blood pressure (mBP), heart rate, ambient temperature, atmospheric pressure, relative humidity, wind speed, precipitation, sunshine duration, sex, glaucoma type, glaucoma stage, number of eye-drops used, season, time of day and weather. Results A total of 2655 IOP measurements from 154 eyes of 77 patients (mean age: 65.8 years; mean observation period: 5.2 years) were analysed. IOP was negatively correlated with ambient temperature (estimate=−0.029; p=0.003) and positively correlated with mBP (estimate=0.021; p<0.001). CCT tended to be associated with IOP. The number of eye-drops used, glaucoma type, and time of day had a significant effect, and season tended to have an effect, on IOP fluctuation. Conclusions In patients with stable POAG under medical treatment, ambient temperature showed a significant and negative correlation with IOP after correction for the effects of other confounding and possibly correlating factors.