At what time of the day is the intraocular pressure highest?

Intraocular pressure (IOP) often exhibits diurnal variation, meaning it fluctuates throughout the day. Typically, IOP is highest in the early morning hours, soon after waking. This increase can be attributed to various physiological changes during sleep, including reduced aqueous humor outflow. During the night, the body is in a supine position, which can lead to a change in drainage dynamics of the aqueous humor.

Morning pressure is particularly important to consider in the context of conditions such as glaucoma, as elevated morning IOP can increase the risk of optic nerve damage. Monitoring IOP at different times of the day can aid in diagnosing and managing conditions affecting the eye.

In contrast, IOP tends to decrease gradually throughout the day, reaching its lowest levels in the late afternoon or evening. Thus, while fluctuations occur at various times, the highest point of intraocular pressure is consistently recorded in the morning.