Einstein International Journal Organization(EIJO)

Abstract

Background: Intraocular pressure (IOP) is the most important modifiable risk factor for glaucoma and is influenced by multiple physiological and environmental factors. While diurnal variation of IOP is well documented, seasonal variation remains less explored, particularly in young healthy populations from subtropical regions.

Aim: To evaluate seasonal variation of intraocular pressure in young healthy volunteers and assess its association with ambient temperature and humidity.

Materials and Methods: This prospective longitudinal observational study was conducted over 12 months in a tertiary care teaching hospital. Forty healthy volunteers (80 eyes) aged 18–30 years were included. IOP was measured once in each season (Winter, Summer, Monsoon, and Autumn) using Goldmann applanation tonometry between 9:00 AM and 11:00 AM to minimize diurnal variation. Three consecutive readings were averaged for analysis. Ambient temperature and relative humidity were recorded on examination days. Repeated measures ANOVA was used to compare mean IOP across seasons, followed by Bonferroni post-hoc testing. Pearson correlation and linear regression analyses were performed to evaluate associations with environmental parameters.

Results:  Mean IOP was highest in Winter (16.41 ± 1.72 mmHg) and lowest in Summer (14.85 ± 1.54 mmHg), with intermediate values in Monsoon and Autumn. Repeated measures ANOVA demonstrated significant seasonal variation (F = 7.481, p = 0.00013). Post-hoc analysis revealed significant differences between Winter and Summer (p = 0.0021). Linear regression showed a significant inverse relationship between temperature and IOP (β = –0.077 mmHg/°C, p < 0.001).

Conclusion: Significant seasonal variation in IOP exists among young healthy individuals, with higher values in winter and lower values in summer. Recognition of this physiological fluctuation is important for accurate interpretation of IOP measurements in clinical practice.

Keywords: Intraocular Pressure, Seasonal Variation, Young Adults, Ambient Temperature Goldmann Applanation Tonometry, Aqueous Humor Dynamics, Ocular Physiology, Environmental Influence.

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