Green Star

2023 Author: Wallace Forman | [email protected]. Last modified: 2023-08-25 11:04

Glaucoma (green star)

Glaucoma is a group of different diseases that often have high intraocular pressure. There is damage to the optic nerve of the papilla, a point where the optic nerve emerges from the eye, as well as a restriction of the field of vision - in the worst case, blindness.

There are different forms of glaucoma, with different causes. The relatively common primary open-angle glaucoma is one of the different forms of glaucoma.

In the case of glaucoma, for example, the so-called chamber angle can be misplaced, narrow or blocked. Certain diseases can be involved in the development of glaucoma - such as diabetes mellitus. In addition, there are injuries associated with the development of glaucoma and the use and intake of certain medications (e.g. cortisone), heredity, age, etc. Not all factors for the development of glaucoma are known so far.

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Glaucoma & intraocular pressure

The eye needs a certain amount of pressure in order not to collapse and to keep the almost round shape that is necessary for optimal vision. The intraocular pressure is decisive for the stable shape of the eye. The intraocular pressure is maintained to a large extent by the aqueous humor of the anterior and posterior chambers of the eye. The aqueous humor is constantly being formed and is also important for supplying the cornea and lens with nutrients. As much aqueous humor is constantly being formed as it drains, so that there is equilibrium. If the outflow of aqueous humor does not work properly, the fluid builds up and the intraocular pressure increases. The high pressure can seriously damage the eye (e.g. the optic nerve), so that in the worst case scenario, blindness can occur.

Graphic glaucoma © Henrie

A large part of the outflow of aqueous humor is regulated by the outflow resistance in the trabecular system of the chamber angle (trabecular outflow). A smaller part is transported away in various other ways. An increase in pressure is often caused by an obstruction of the aqueous humor outflow in the trabecular system, which is usually caused by pathological changes. There may also be a narrow chamber angle and a rare congenital developmental disorder of the chamber angle (congenital glaucoma).

The statistical norm of intraocular pressure is between ten and 21 mmHg. The intraocular pressure changes - for example, during the day and with age. Values above or below the norm and large fluctuations in the values can, however, indicate diseases of the eye. The intraocular pressure values measured by applanation tonometry also depend on the thickness of the cornea to be applanated during the measurement.

Glaucoma - forms

The types of glaucoma include:

• primary open-angle glaucoma - a particularly common form. It is chronic and affects both eyes. It often goes unnoticed for a long time by those affected because there is no pain. In addition, impairing visual disturbances are often only perceived when the damage has already progressed. Prevention is therefore particularly important!
• so-called normal pressure glaucoma - a glaucoma without high pressure. The intraocular pressure is within the normal range (below 21 mmHg). In those affected, however, this pressure shows damage typical of glaucoma, such as the optic nerve, and visual field defects. It is assumed that this pressure, even if it is within the statistical norm, is too high for the individual concerned. The cause is believed to be a combination of blood flow components and relatively high intraocular pressure. Therefore, factors such as a pronounced drop in blood pressure at night, circulatory disorders in the carotid arteries, etc. are examined in these patients.
• Angular block glaucoma, in which the angle of the chamber is misplaced. The acute angular block ("glaucoma attack") develops through a sudden displacement of the chamber angle, so that the intraocular pressure increases sharply within a few hours. The consequences: severe pain and visual disturbances (visual field defects) as well as the risk of severe damage to the optic nerve (blindness!). Often there is a congenital narrow chamber angle, farsightedness and a relatively large lens. In older people, acute angular blockages usually occur spontaneously as a result of drug-induced pupillary dilation during eye examinations. If the anterior chamber is flattened, these are therefore not administered.
• congenital glaucoma. This rare congenital form can - if not recognized in time - lead to blindness relatively quickly. It usually shows up in the first year of life. This is one of the reasons why eye examinations should be carried out on babies and toddlers, and suspicions, problems and abnormalities should be clarified quickly.

Glaucoma & Risk

Not all factors for the development of glaucoma are known so far. In general, the risk of primary open-angle glaucoma increases with age (over 70 years of age); ophthalmologically, screening is recommended from the age of 40 (!). Because the ophthalmologist can recognize damage early on and initiate treatment at an early stage. The plant can be inherited. If parents and / or siblings have glaucoma, the risk of glaucoma is increased. In addition to high intraocular pressure, other risk factors for glaucoma include:

• greater farsightedness,
• stronger myopia (from -5dpt),
• Diseases (diabetes mellitus), eye diseases, injuries to the eye, inflammation of the inside of the eye,
• Using or taking certain medications (cortisone),
• low corneal thickness (thin central corneal thickness),
• severe cardiovascular disease.