Background: The aim of this study was to provide data, on the distribution or intraocular pressure (IOP) in Tehran population.

Materials and Methods: Through a population-based, cross-sectional study, a total of 4565 Tehran citizens were studied in the Tehran Eye Study. The findings of the participants (n=3834) 10 years and older free of glaucoma diagnosis or suspicion who had undergone applanation tonometry examination are presented. All participants received a standardized protocol included applanation tonometry, and some other ocular measurements, fundus examination, demographic data and an interview. IOP measurement was used to evaluate its distribution by age, sex, and some eye parameters.   ‎

Results: Mean ± SO IOP was 14.5±2.6 in the total population, 14.4±2.7 in men, and 14.5±2.5 in women. Normal range (mean±2SD) of IOP was determined to be 9.3 - 19.7 mmHg. IOP increased significantly with age and cup-disc ratio except for a fall in old ages. This relationship was also observed when we analyzed individuals without diabetes or hypertension history. IOP increased with darker eye pigmentation except for blue/gray eyes. There was a non-linear ‎increase of IOP from emmetropic to high myopic eyes. ‎

Conclusion: Mean and/or normal range of IOP and their associations have been reported with wide differences in various studies. It is wise that studies evaluate IOP distribution or associations in healthy people and glaucoma people separately and also report the prevalence of IOP risk factors in their population to allow for a logical comparison of studies.