Season, weather and intraocular pressure: a monocentric retrospective analysis from 2016 - 2021

Abstract

Background We herein investigate the relationship between intraocular pressure (IOP) and environmental factors such as daily mean temperature, daily sunshine duration and daily mean atmospheric pressure.Methods We reviewed all IOP measurements of out-patients by non-contact tonometry that had been recorded between 2016 and 2021 (N = 199,804) in the Eye Center, University Hospital Freiburg, Germany. IOP values below 5 and above 30 mm Hg were excluded. No other exclusion criteria applied. Analysis of variance was performed to assess seasonal variations in IOP. We fitted a linear regression model to analyze the respective influences of age at time of measurement, daily mean temperature, daily sunshine duration and daily mean atmospheric pressure on IOP. We also performed cross-correlations to check for periodicity and time lag between IOP and the aforementioned environmental factors.Results IOP was highest in January (15.0 ± 3.8 mm Hg) and lowest in July (14.6 ± 3.6 mm Hg). Cross-correlation and Fourier analysis support annual periodicity and a seasonal pattern of IOP. Multiple linear regression revealed a significant negative correlation of daily mean temperature with IOP. Sunshine duration at the day of measurement did not correlate with IOP, but the total sunshine duration of the preceding ten days before measurement revealed a significant negative correlation. Atmospheric pressure missed statistical significance at multifactorial level.Conclusions We observed an annual periodic IOP variation with an amplitude of ≈ 0.4 mm Hg. The variation is most likely attributable to a direct effect of environmental temperature and secondly to biological factors triggered by sunshine exposure over the preceding ten days.