The What, Why, and How of Eye Pressure

Eye pressure, also known as intraocular pressure (IOP) measures the fluid pressure inside the eye. Vitreous humor is a jelly-like substance that fills most of the back part of the eye. Aqueous humor is also there, mostly in front of the eye behind the cornea and in front of the iris. Aqueous humor is more watery, and in healthy eyes it into the eye while the same amount drains out. When the amount flowing in and out are equal, it creates a stable eye pressure. If the drainage angle becomes blocked and more fluid flows in than what can flow it, this leads to high fluid pressure.

Generally, IOP between 10 and 20 is considered normal. If someone has elevated pressure but no symptoms, it is considered ocular hypertension. With glaucoma, elevated pressure causes damage to the optic nerve. Damage from glaucoma cannot be reversed, so it is important to catch it early. It is possible to have high pressure with no damage and vision loss with normal pressures.

At our office, we do not use the puff test to measure IOP. Our test is fast, simple, and painless.