Evaluation of Diurnal Variations of Intraocular Pressure in a Normal Iranian Population

To evaluate diurnal variations in intraocular pressure (IOP) in normal adult residents of Yazd city. This cross-sectional study was performed on 800 eyes of 400 subjects aged between 20-80 years selected by cluster random sampling from residents of Yazd city during 2004-2005. IOP was measured by Goldman applanation tonometer in the morning (8-9 AM) and evening (8-9 PM). The difference between the two measurements was considered as diurnal variation of IOP. Mean IOP was 14.80±1.83 mmHg in the morning and 11.58±2.0 mmHg in the evening in right eyes and 14.79±1.89 mmHg in the morning and 11.33±2.0 mmHg in the evening in left eyes (P< 0.001). Mean diurnal variation of IOP was 3.23±1.23 mmHg in females, 3.46±1.23 mmHg in males and 3.34±1.05 mmHg, overall (P< 0.001). Morning IOP was higher in 84%, the same in 13.6% and lower in 2.4% compared to evening values. IOP increased with aging. There was no significant difference in mean IOP between males and females. This study revealed that IOP is usually higher in the morning in both eyes and increases with ageing in both sexes.