Objective: Although the intraocular pressure (IOP) is the most important factor related to the onset and progression of glaucoma, there is little evidence on long-term aging effects on IOP. This article examines the changes of IOP over 10 years in normal eyes to assess physiologic changes related to aging.
Design: Population-based long-term longitudinal study. STUDY POPULATION AND OBSERVATION PROCEDURE: Two thousand nine hundred eighty-seven Japanese male aircraft crew members underwent IOP measurement by Goldmann apparatus and received physical and complete ophthalmologic examinations every year for 10 years. A total of 2330 healthy persons (21-49 years; mean age, 35.9+/-6.8 [standard deviation]) who had no history of treatment for ophthalmic diseases, current illnesses, and no missing data for 10 consecutive years were analyzed.
Main outcome measures: For analysis of the longitudinal index (trend), the linear regression coefficients for 11 points of measurement were determined. Ophthalmologic and physiologic factors affecting the 10-year mean values and a trend of IOP were examined by multivariable linear regression analysis.
Results: Intraocular pressure tended to decrease with age in all age groups. The mean linear regression coefficient (right eye/left eye) = -0.076/-0.060 (95% confidence interval [CI]: (-0.094 to -0.057)/(-0.078 to -0.041), -0.073/-0.060 [95% CI: (-0.084 to -0.062)/(-0.071 to -0.049)], and -0.060/-0.050 [95%CI: (-0.075 to -0.046)/(-0.064 to -0.036)] (mmHg/year) in the 20s, 30s, and 40s, respectively). In investigating correlations between the 10-year mean values of IOP and factors examined in this study, multivariate analysis showed a significantly inverse correlation with spherical power (partial regression coefficient [B] = -0.155/-0.144) and positive correlation with esophoria (B = 0.536/0.521), systolic blood pressure (B = 0.021/0.022), heart rate (B = 0.024/0.024), and hematocrit (B = 0.041/0.043) with IOP. The trend of IOP was significantly positively associated with the trends of systemic factors: body mass index (BMI) (B = 0.117/0.119), blood pressure (systolic) (B = 0.020/0.020), and hematocrit (B = 0.057/0.045), but not with any ophthalmologic factor.
Conclusions: The long-term observation clearly demonstrated that, in normal eyes, the IOP decreased with aging. The IOP value was negatively associated with spherical power and positively with esophoria, blood pressure, heart rate, and hematocrit. The change of IOP could be affected mainly by the change of body mas index, blood pressure, and hematocrit.