Effects of Climatic Factors on the Intraocular Pressure in Normal Eyes under Everyday Conditions

Abstract

Abstract Background/Objectives:Little is known about effects of climatic factors on intraocular pressure (IOP) in normal eyes. The purpose of this study is to investigate correlation between climatic factors and Goldmann applanation tonometer-measured IOP (GAT-IOP) in normal eyes under everyday conditions. Subjects/Methods: Data from 2,341 normal eyes 2,341 subjects; mean age, 56.9 years) who participated in a population-based glaucoma survey in Japan were analyzed using the multivariable regression analysis, in which the GAT-IOP was the response variable; explanatory variables were the hourly time of day and day of the week/month when each subject was examined, ocular and systemic factors reportedly correlated with GAT-IOP and ambient atmospheric pressure (AP), relative humidity (RH), temperature, wind speed, amount of precipitation, and weather. Results: The AP of the outside air when each subject was examined and the average AP and RH of the outside air over 24 hours before each subject’s examination were positively (P=0.0001, P=0.0056, P=0.0112, respectively) correlated with the GAT-IOP. The central corneal thickness, body mass index, and systolic blood pressure were positively (P<0.0001, P=0.0001, P=0.0007, respectively), corneal curvature radius and age were negatively (P=0.0168, P=0.0056, respectively) correlated with the GAT-IOP. The GAT-IOP measured on various days of the week and months fluctuated significantly (P<0.0001). Conclusions:After adjusting for the effects of other possibly confounding factors, the GAT-IOP was significantly positively correlated with ambient AP and RH in normal eyes under everyday conditions. The effects of systemic, ocular factors and month on the GAT-IOP obtained were compatible with those previously reported.