What are the reasons for eye pressure

useful information

What is eye pressure?

Eye pressure or intraocular pressure (IOP) is the name given to the fluid pressure inside the eye caused by the aqueous humor. This aqueous humor is synthesized and secreted by the ciliary body - a special tissue that is located circularly behind the iris (iris) at the posterior chamber angle. It consists mainly of water. There are two different chambers of the eye in the eye: an anterior and a posterior chamber. This produced aqueous humor reaches the anterior chamber via diffusion past the lens from the posterior chamber. The flow through the eye chambers ends in the so-called Schlemm's Canal, which is located in the inner corner of the eye and represents the drainage for said fluid. In terms of the structure of the tissue, it is comparable to a lymphatic vessel. Both production and drainage of the aqueous humor are subject to constant control - with the aim of always keeping these two processes in a precise balance. Should the balance shift in one direction or the other, this can - depending on the extent - have serious consequences.
The intraocular pressure is the pressure that weighs on the inner wall of the eye and thus fulfills various functions. Normal intraocular pressure is around 15.5 mmHg. The respective lower and upper limits for a potentially pathological intraocular pressure are 10 mmHg for a greatly reduced pressure and 21 mmHg for a greatly increased pressure.
In this context, special attention is paid to the increased eye pressure - a so-called ocular hypertension. If the increased pressure also leads to a pinching of the optic nerve with corresponding visual field defects, one speaks of a glaucoma.

Causes of increased eye pressure

Increased eye pressure - that is, a pressure of over 21 mmHg - does not always have to be of a pathological nature. There are many causes that can produce such symptoms, especially in the elderly. If increased intraocular pressure is found, a detailed examination should be carried out by an ophthalmologist in order to determine one or more possible causes. Sometimes increased intraocular pressure is also an indication or symptom of an underlying systemic disease that requires appropriate treatment. Basically, too high a pressure arises either with excessive production or a disturbed drainage of the aqueous humor. Both can be caused by anatomical changes in the structure of the eye or the vascular system. And such a change, in turn, can be caused by various risk factors in addition to certain underlying diseases (e.g. diabetes mellitus). The most common risk factors include:

  • Age (older people are affected much more often)
  • Genetic disposition (family history of increased eye pressure) or ethnic factors (e.g. dark skin color)
  • Acute inflammation of the eye or previous trauma
  • migraine
  • A severe ametropia with corresponding changes in the eye tissue
  • Certain drugs

Due to the wide range of possibilities, it is advisable to seek advice from a specialist - also in order to identify and treat possible, hidden causes. Especially people to whom one or more of the risk factors listed here apply should have their eye pressure measured regularly.

Risks of increased eye pressure

As already mentioned, the body is careful to always maintain a stable environment in the eye with pressure conditions that are as constant as possible. And for good reason: Large fluctuations in pressure can have a dramatic impact on our eyesight. In the case of ocular hypertension (increased eye pressure), the optic nerve (nervus opticus) can be partially clamped, which has a direct effect on the ability to see - the consequences are visual field defects, impaired vision or even blindness. The more acute such symptoms are, the sooner an ophthalmologist should be consulted and a corresponding check-up should be carried out. Because depending on the severity and course of the problem, time can be a decisive factor in terms of the chances of recovery and the regeneration process. Particular caution is required if it is a possible acute glaucoma attack, which is manifested by a spontaneous deterioration in vision, accompanied by pain and possibly nausea and vomiting.


The first thing that is usually done is an ophthalmoscopy, which offers the opportunity to take a closer look at the fundus. This makes it possible to identify any degenerative changes or an optic nerve problem.
Of course, if there is a specific suspicion of increased intraocular pressure, this is also measured. This is done using tonometry, whereby the small measuring head of the tonometer determines the intraocular pressure by applying pressure to the cornea. In addition to determining the actual intraocular pressure, this examination also allows conclusions to be drawn about any different forms of glaucoma. The chamber angle - and thus the Schlemm's canal (drainage of the aqueous humor) - can be viewed more closely with a gonioscopy.
If potential restrictions or an affliction of the optic nerve have already been discovered, the size of the visual field can be determined using perimetry. This enables visual field defects to be detected and determined.

If you have any further questions about the exact procedure or if you would like an examination and measurement of the eye pressure, the specialists at the Wetzikon Eye Clinic will be happy to assist you.

This article corresponds to the current state of science

Causes and risks of increased intraocular pressureOphthalmologists Wetzikon2018-12-08Ophthalmologists Wetzikon - Leue Center