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Intraocular pressure - normal values, symptoms and causes

Intraocular pressure - normal values, symptoms and causes


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Increased and too low intraocular pressure

The right pressure conditions in the eye are essential for trouble-free vision. It can be all the more dangerous if the intraocular pressure (tensio) is impaired by health problems. This is usually due to pathological changes in the eye that prevent the proper drainage of the eye's own aqueous humor.

Definition

The internal pressure in the eye (Oculus) is crucial for numerous factors that determine the eye functionality as well as its anatomy. For example, the intraocular pressure ensures a constant distance between

  • Cornea (Cornea)
  • Eye lens (Phaco)
  • and Retina (Retina),

On the one hand, this ensures optimal ventilation of the skin's own layers of skin and, on the other hand, it also prevents these layers from interfering with each other in their visual function by sticking together.

The function of these skin layers is also influenced by the intraocular pressure. For example, it ensures that the Visual cells (Facet receptors), which are located in the retina and are responsible for the absorption of light in the eye. Without adequate pressure conditions in the eye, people have problems with light-dark vision.

In addition, the intraocular pressure is also responsible for an adequate curvature of the inner wall of the eye, which is necessary to ensure perfect vision and to be able to perceive visual impressions to the left and right of the central field of vision.

The natural intraocular pressure is between 10 and 21 mmHg. This comes about through the so-called Aqueous humor (Humor aquosus). As the name suggests, this eye fluid is in the Eye chamber (Camerae bulbi), which can be divided into a front and a rear eye chamber. The anterior chamber forms the hollow vault of the eye directly behind the cornea, while the posterior chamber surrounds the lens between the Rainbow skin (Iris) and the vitreum in the skull.

The aqueous humor is formed in the Ciliary processes (Corpus ciliare). They are located on the side behind the pupil and generate the eye fluid from components that, with the exception of the red blood pigment, are very similar to those of the blood serum and are composed as follows:

  • water
  • amino acids
  • antibody
  • Ascorbic acid
  • Electrolytes
  • Lactic acid
  • Proteins

Every day, between 3 and 9 ml of aqueous humor are produced in the ciliary bodies, which initially pour into the eye chamber and regulate the intraocular pressure and adequately moisturize the eye. Then the eye fluid flows over the Chamber angle (Angulus iridocornealis) in the Schlemm Canal (Plexus venosus sclerae) off again. Named after the German doctor and anatomist Friedrich Schlemm, this channel transfers the aqueous humor back into the bloodstream via a fine network of veins in the eyes.

And this is exactly where the most common cause of increased intraocular pressure lies. Because when the aqueous humor can no longer drain completely, for example due to blockages in the chamber angle or Schlemm's canal, the pressure in the eye chambers increases.

Likewise, there can be a low intraocular pressure if the aqueous humor drains away too quickly. In both cases, the patient's eyesight is extremely at risk. Irreparable damage to the eyes can also occur, which is why timely treatment of a disturbed intraocular pressure is very important.

Causes of increased intraocular pressure

As already shown, the intraocular pressure is caused by the amount of aqueous humor that is in the anterior chamber of the eye in the eye chamber. A constant intraocular pressure is therefore essential for the eyesight, since only then can all eye structures involved in the vision adequately fulfill their tasks. On the other hand, if there is too much pressure inside the eye, the functionality of the fine and sensitive eye elements is impaired enormously. Corresponding pressure increases usually result from one of two influencing factors:

  • Either because of a pathological change in the eye, more aqueous humor is produced than can drain,
  • or because of a pathological change in the eye, less aqueous humor is removed than is produced.

In both cases, the imbalance from increased production and / or reduced discharge results in an increased one IOP (intraocular pressure)as the intraocular pressure is called in specialist circles.

The reason for this is, for example Narrowing (Stenoses) in the chamber angle, or in the Schlemm Canal in question. This may be the case, for example, due to changes in the vessels or malformation. Other diseases that cannot be ruled out as the cause of increased eye pressure due to disturbed aqueous humor drainage are cysts, tumors and inflammation in the area of ​​the chamber angle.

In addition, injury to the eye, foreign bodies, adhesions in the eye tissue (e.g. through surgical scars) and a longstanding diabetes disease able to constrict the vessels of the drainage system in the eye in such a way that aqueous humor accumulates and the intraocular pressure rises.

Often underestimated as the cause of increased intraocular pressure stress and Medication. For the eye, stress influences arise not only from hectic everyday situations. Environmental pollutants, the persistent tremors of heavy loads can also be (due to increased pressure load) and diseases such as high blood pressure increase eye stress.

In the area of ​​active pharmaceutical ingredients, numerous drugs can also increase IOP as a side effect. This happens very often, for example, during treatment with cortisone. For this reason, it is recommended to have the eyes checked by a doctor before and during a long-lasting cortisone therapy.

Medications used to treat cancer are also known to increase intraocular pressure. In addition, decongestant nasal sprays are currently at least suspected of provoking increased pressure values.

Attention: In all the cases mentioned, a so-called “untreated” can result from the permanently increased intraocular pressure glaucoma arise. Better known as "the glaucoma", this disease hides irreparable damage to the optic nerve. The risk of developing glaucoma is not exactly low. In Germany alone, around 5 million people are at increased risk of glaucoma and around 800,000 people have glaucoma. In fact, this disease is often preceded by increased intraocular pressure.

Causes of low intraocular pressure

A too low intraocular pressure, which is caused by too little aqueous humor in the eye chamber, can lead to serious health consequences for the eyesight. The underlying mechanism here is the exact opposite of the mechanism for increased intraocular pressure. This means that there is reduced pressure in the eye

  • either by a reduced production of aqueous humor,
  • or caused by increased drainage of the aqueous humor.

A reduced production of aqueous humor can occur, among other things, due to a pathological change in the ciliary body. Again there are stenoses in the area of ​​the ciliary body, (e.g. due to cysts, injuries or inflammation) to name as conceivable causes.

Excessive outflow of aqueous humor, on the other hand, can also occur unintentionally after interventions in the eye, for example in glaucoma patients. In this case, an operation to improve the outflow of eye fluid leads to an undesired lowering of the intraocular pressure beyond the desired standard value.

Warning: A permanent or long-lasting reduction in IOP can lead to detachment of the retina from the choroid below. In the worst case, this retinal detachment provokes complete vision loss and thus blindness!

Diagnosis

Changes in intraocular pressure are often gradual processes, the consequences of which are not apparent until very late in the advanced stage of the disease. However, since the glaucoma mainly manifests itself from the second half of life and disturbances in the outflow or the production of aqueous humor are often due to age-related eye remodeling processes, it is recommended that from the age of 40 about every one to two years Have your eyes checked for eyesight and intraocular pressure as a precaution.

Important: However, it should be pointed out that these are not examinations, the costs of which are generally borne by the health insurance companies, but rather so-called individual health services (iGeL), which have to be self-financed or only subsidized. The benefits are only taken over by the health insurance if there is an increased risk profile or if there is a follow-up check for existing diseases.

The family doctor often makes a first suspected diagnosis of an intraocular pressure that falls outside the normal range simply because of the presence of characteristic symptoms and risk factors. As soon as these come up within a medical history and a suspicion arises, family doctors usually refer the person concerned to a local ophthalmologist or a hospital with an ophthalmological examination (affecting the eye) Department. The appropriate equipment for the diagnosis of eye diseases is available here and can reliably detect even the smallest inconsistencies.

Regardless of how the patient comes to the ophthalmologist, the diagnosis of changes in intraocular pressure comprises several examination steps. Which includes:

  • Measurement of intraocular pressure (Tonometry)
  • Mirroring (Ophthalmoscopy)
  • Eyesight testing (Visual test)

Measurement of intraocular pressure

The ophthalmologist has several measurement methods available for measuring IOP. In healthy people, the normal value is between 10 and 21 mmHG, whereby the age, body constitution, blood pressure, pulse and even the time of day can generate a wide range of fluctuation, which the examining doctor must take into account. In order to measure as accurately as possible, there are various approaches that are constantly being developed:

1. Goldmann applanation tonometry: With Goldmann applanation tonometry, the ophthalmologist briefly presses the previously anesthetized cornea into a certain depth using a 3 mm wide pressure sensor. The more force is required to flatten the cornea to the desired depth (to be applied), the higher the existing intraocular pressure.

2. Non-Contact Tanometry: A somewhat newer method does not require direct contact with the cornea and is therefore also called non-contact tonometry. Here, a device blows an air jet onto the cornea of ​​the open eye and determines the pressure inside the eye from the measured time it takes for the air pulse to flatten the cornea to a certain depth.

3. Measurement with contact lens microsensor: Research is very intensively concerned with the development of better measurement techniques. Among other things, contact lenses with microsensors are currently being developed, which should be able to measure IOP continuously over a longer period of time.

Mirroring

In the case of eye mirroring, the ophthalmologist uses an ophthalmoscope to examine the fundus that is normally not visible from the outside. He can check several structures for pathological changes. For example, the optic nerve located in the back of the eye and the yellow spot can be inspected more precisely by the incidence of light from the ophthalmoscope. Even fine layers of tissue such as the retina and choroid together with their fine blood vessels for the care of the eye can be seen thanks to the mirror reflection.

Using this approach, the ophthalmologist can assess whether there are signs of damage to the optic nerve as a result of pathological changes in the IOP (with increased intraocular pressure) or on the retina (with low intraocular pressure) have set and check their course exactly.

The examination method itself is painless, but it must be noted that the eye is treated beforehand with atropine drops, which cause the pupil to widen to allow a better view of the fundus. Because of their effect, the eye drops are also called “wide drops”. This process affects the eyesight for several hours and the affected person must therefore neither operate machines nor use a vehicle or bicycle on the day of the examination. It is therefore common practice to take time off for the day of the exam.

Eyesight testing

Conducting eye tests during the diagnosis is not directly related to the intraocular pressure, but it can be used to assess whether pathological changes in the eye have already impaired the eyesight or whether there are other visual impairments. To carry out the test, the ophthalmologist has various measuring and comparative methods at his disposal, with which the visual acuity as well as the contrast, color and 3D vision can be assessed and assessed.

Danger: In contrast to the routine check-up or the diagnosis of existing risk factors, an acute glaucoma attack always represents an emergency situation that requires an immediate ophthalmological examination and therapy!

Treatment for changes in intraocular pressure

Which treatment measures are necessary to correct the internal pressure changes in the eye must be decided on a case-by-case basis by the responsible ophthalmologist. However, drug therapy for underlying diseases is usually common. There are also some herbs and home remedies that offer support for increased or reduced intraocular pressure. Nevertheless, eye surgery can never be completely ruled out if the course is unfavorable.

Medication

In the case of changes in intraocular pressure, drug therapy primarily consists of a combination therapy of different eye drops with different active ingredients and therapeutic approaches. Eye drops that contain prostaglandins as an active ingredient are suitable, for example, for improving the outflow of aqueous humor. Eye drops with beta-blockers are used to reduce the production of aqueous humor.

On the other hand, eye drops containing carbonic anhydrase inhibitors are suitable for regulating the production of aqueous humor by promoting blood circulation. A mere regulation of aqueous humor production without a background that promotes blood circulation can be achieved with alpha agonists as an active ingredient in eye drops.

The doctor decides which eye drops should be used in which combination depending on the underlying cause and progress of the disease process. However, it should be noted that therapy with eye drops for pathologically altered intraocular pressure often has to be carried out for a lifetime unless surgical therapy is considered.

Surgical therapy

If retinal detachment has arisen as a result of a low IOP or is in danger of developing, the detached retina can be fused with the underlying choroid using various surgical and laser techniques. If drug therapy is high in the case of increased IOP, there is often only the way here via surgical measures to avoid blindness due to the resulting glaucoma. The surgical approaches depend entirely on the causative mechanism.

If the cause is an overproduction of aqueous humor in the ciliary body, this can be treated with cyclophotocoagualtion. The term describes a special laser technology that ensures that the parts of the ciliary body stop their work and as a result less aqueous humor is produced.

If a drainage disorder is the cause of the change in intraocular pressure, this can be treated using surgical methods such as a viscocanalostomy or a drainage implant. In both cases, the operation is aimed at an additional drainage device.

Naturopathy

Pathological changes in intraocular pressure can rarely be completely treated by the medicinal plant and homeopathic approach alone. However, the affected person has a number of resources available that support the metabolic processes in the eye and thus also serve the conventional medical therapeutic measures.

In homeopathy, for example, the use of the ordinary pasque-band (Pulsatilla vulgaris), Eyebright and the Bach flowers Rock Rose, Rock Water and Walnut have had good success so far. Teas or mother tinctures with the components of horse chestnut are also considered to be helpful as a means of lowering intraocular pressure. Pansies and violets are also used successfully to support therapeutic reduction of IOP.

Self-help and home remedies for increased intraocular pressure

Since stress with increased intraocular pressure is discussed not only as a beneficial but also as a triggering factor, risk patients can also help themselves to keep their IOP in the normal range by avoiding stress, or to bring it back into the normal range.

It is important to learn and apply stress-reducing everyday behavior. This can consist, for example, of planning the daily workload correctly with sufficient rest periods and a regular sleeping rhythm. The latter is particularly important because the eyes can rest intensively during sleep. Targeted relaxation training, such as through yoga, meditation or progressive muscle relaxation, can also help reduce stress.

Another important point in the private support of therapy is a balanced diet. A diet rich in magnesium, carotene and vitamins is particularly important here, since these nutrients strengthen eye function to a special degree. This applies in particular to magnesium, which is found abundantly in cereals and legumes such as peas, beans, corn, sesame, linseed, amaranth, quinoa, sunflower and pumpkin seeds and in bananas. Furthermore, the consumption of green tea is said to promote blood circulation in the eyes.

Discontinue or at least reduce patients with unhealthy (especially too high) However, eye pressure is coffee and other caffeinated foods. Because caffeine raises blood pressure, which can worsen the symptoms in the case of excessive IOP. (ma)

Author and source information

This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.

Swell:

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  • Franz Grehn: Ophthalmology, Springer Verlag, 29th edition, 2005
  • Gerhard K. Lang, Gabriele E. Lang: Ophthalmology, Georg Thieme Verlag Stuttgart, 1st edition, 2015
  • Karl-Uwe Marx: Complementary Ophthalmology, Hippocrates Verlag, 1st edition 2005
  • Leila M. Khazaeni: Examination for eye diseases, MSD Manual, (accessed August 26, 2019), MSD
  • Cordula Dahlmann, Johannes Patzelt: Ophthalmology, Urban & Fischer Verlag, Elsevier GmbH, 4th edition, 2016


Video: Low Eye Pressure Causes u0026 Management - Dr. Elankumaran P (December 2022).