Synonyms in a broader sense
Medical: Glaucoma
Definition
Glaucoma (but should not be used any more, as it can easily be confused with “cataract” (cataract). Glaucoma is a generic term for a number of diseases that are associated with typical damage to the optic nerve papilla and the visual field. The optic nerve papilla is the point in the eye where nerve fibers exit or enter the brain.
Typical changes in the eye are characteristic for glaucoma: A distinction is made between primary glaucoma and secondary glaucoma. Primary glaucomas (glaucoma) occur spontaneously, while secondary glaucomas are the result of other diseases.
- Individually increased intraocular pressure
- Scotoma (see also our topic “Examination of the visual field”)
- Funnel-shaped depression of the optic nerve papilla with degradation of the nerve fibers (papilla excavation)
Emergence of glaucoma
There is a permanent internal pressure in the eye. On the one hand, this pressure must not be too low, because otherwise the eye would collapse, on the other hand, it must not be too high, because otherwise the optic nerve and the retina would be damaged. The normal pressure is in the range of 10 mmHg to 21 mmHg.
The pressure is regulated by the aqueous humor. The aqueous humor is produced in the posterior chamber of the eye at the ciliary body, an important structure behind the iris. From there, it flows into the anterior chamber of the eye, in front of the iris, and then flows off in the chamber angle through the so-called trabecular meshwork (trabecular drainage) into the Schlemm canal.
A small portion of the aqueous humor is also absorbed by the vessels of the choroid (uvea) (uveoscleral outflow). If this outflow is disturbed, glaucoma occurs. Since glaucoma is characterized by different forms and different types of glaucoma, a distinction is made between the following types of glaucoma Primary open-angle glaucoma is the most common form of glaucoma (about 90 percent of all glaucomatous diseases).
Important risk factors that influence the development of open-angle glaucoma are
- Open angle glaucoma: Cartilage-related substance deposits in the trabecular meshwork Special forms: ocular hypertension and normal pressure glaucoma
- Special forms: ocular hypertension and normal pressure glaucoma
- Angular block glaucoma: relocation of the chamber angle due to a too narrow chamber angle or adhesions (goniosynechia)
- Subtypes of angle block glaucoma: Acute angle block glaucoma: Either a narrow chamber angle, farsightedness or a relatively large lens, e.g. the age lens. But also the dilatation of the pupil, as is the case in darkness, or pupil dilating eye drops are frequent triggers Intermittent angle-block glaucoma: Preliminary stage of acute angle-block glaucoma Chronic angle-block glaucoma: Adhesions of the chamber angle, e.g. due to untimely treatment of acute glaucoma Congenital glaucoma: Maldevelopment of the trabecular meshwork
- Acute angle block glaucoma: Either a narrow chamber angle, farsightedness or a relatively large lens, e.g. the age lens.
But also the dilation of the pupil, as is the case in darkness, or pupil dilating eye drops are frequent triggers
- Intermittent angular block glaucoma: Preliminary stage of acute angular block glaucoma
- Chronic angle block glaucoma: adhesions of the chamber angle, e.g. due to untimely treatment of acute glaucoma
- Congenital glaucoma: maldevelopment of the trabecular meshwork
- Special forms: ocular hypertension and normal pressure glaucoma
- Acute angle block glaucoma: Either a narrow chamber angle, farsightedness or a relatively large lens, e.g. the age lens. But also the dilation of the pupil, as is the case in darkness, or pupil dilating eye drops are frequent triggers
- Intermittent angular block glaucoma: Preliminary stage of acute angular block glaucoma
- Chronic angle block glaucoma: adhesions of the chamber angle, e.g.
due to untimely treatment of acute glaucoma
- Congenital glaucoma: maldevelopment of the trabecular meshwork
- Neovascularization glaucoma (neovascularization = formation of new blood vessels): New blood vessel formation and fibrovascular membranes in the area of the chamber angle lead to occlusion (often in diabetes mellitus or occlusion of central veins of the eye)
- Pigment dispersion glaucoma: deposits of pigment in the chamber angle
- Pseudoexfoliation glaucoma: Fine fibrillar deposits (mainly from the cialial body)
- Cortisone glaucoma: accumulation of mucus components (mucopolysaccharides) in the chamber angle, caused by high and prolonged corticosteroid medication (cortisone treatment)
- Inflammatory glaucoma: fluid congestion (edema) or deposits of inflammatory proteins in the chamber angle
- Glaucoma caused by injuries: Torn or scarred chamber angle
- Rieger syndrome, Axenfeld anomaly, Peter’s malformation: developmental disorders and malformations of the chamber angle
- An age over 65 years
- Diabetes mellitus
- Certain cardiovascular diseases (condition after heart attack, heart failure)
- Nearsightedness and farsightedness (myopia)
- Long lasting (chronic) inflammation of the eye
- Chronic cortisone – Intake
- Increased occurrence in the family (e.g. with parents, grandparents, etc. )
Suddenly strong pain appears in the diseased eye, as well as in the equilateral half of the face. They are described as dull, oppressive or deep-seated and are initially often confused with a headache attack.
They may radiate into the entire face, the teeth or even into the abdomen. Sometimes patients suffer from dizziness through the eye
- Glaucoma attack/acute angle block
The diagnosis of glaucoma includes the examination of intraocular pressure (tonometry), visual field (perimetry) and the ocular fundus (ophthalmoscopy), with special interest in the optic nerve disc. First indications of glaucoma result in an intraocular pressure > 21 mmHg.
But even intraocular pressures in the normal range (10-21 mmHg) can cause glaucoma (see normal pressure glaucoma)! The visual field examination is used to determine the extent of the damage. In primary open-angle glaucoma, the visual field loss (scotoma) often develops very slowly, so that limitations are only perceived subjectively at a very late stage.
Finally, ophthalmoscopy allows the optic nerve papilla to be assessed. This is the point in the eye where the nerve fibers exit or enter the brain. Due to the increased intraocular pressure, or in the case of normal pressure glaucoma even if the intraocular pressure is statistically normal, the papilla can be dented (papilla excavation).
The extent of the indentation is closely related to the degree of damage. The greater the depression, the greater the damage. In further glaucoma examinations, the angle at which the aqueous humor drains can also be examined.
For this purpose, the physician uses a slit lamp and so-called gonioscopy lenses, which are placed on the anesthetized cornea and by means of which it is possible to examine the chamber angle. In this way, possible adhesions (goniosynechia) that obstruct the outflow can be detected. The symptoms of glaucoma indicate an acute glaucoma attack.
Since the cause is an “angle block”, angle assessment (gonioscopy) is particularly important. The diagnosis of secondary glaucoma is based on the results of the eye examination and the underlying disease that caused the glaucoma. In the case of a glaucoma attack, the increased intraocular pressure must first of all be reduced by the usual medication (see above).
Then an operation is performed, even if the intraocular pressure has been successfully lowered! Doctors speak of an ‘iridectomy’: During the procedure, a small piece of the iris, usually in the upper part of the eye, is removed. This creates an artificial connection between the anterior and posterior chamber of the eye.
The aqueous humor can flow directly into the anterior chamber and the angle block is bypassed. In addition to this surgical procedure, there is also the possibility of laser treatment. A high-power Nd:YAG laser is used to shoot a hole into the iris, thus creating an immediate outflow into the anterior chamber of the eye.
Laser iridectomy is particularly suitable for patients whose intraocular pressure has been reduced very successfully with medication, but also as a precautionary measure in the second eye. In addition, the laser method can be a real alternative for patients whose poor general condition no longer permits conventional operations. As a rule, the laser intervention is performed under local anesthesia of the eye.The classic surgery for glaucoma can be performed under local or general anesthesia.
In case of congenital glaucoma, medication is not sufficient and the newborn has to be operated (filtration surgery, trabeculectomy). If glaucoma develops due to another eye disease, the therapy of this eye disease is the main focus. Of course, the intraocular pressure has to be lowered by known methods first.
Unfortunately, glaucoma is not curable according to current research. However, modern medicine offers numerous possibilities to strongly influence the progression of the disease. In the first place, the early detection of glaucoma is the most important.
Because if the disease is detected early, the chances of largely stable, lifelong vision are very good. So far, there are no studies on whether a nationwide glaucoma early detection makes sense and whether it is covered by health insurance companies. However, if there is an initial suspicion of glaucoma, as is the case with family history of glaucoma, personal risks (diabetes mellitus, long-term treatment with steroids such as cortisone, etc.)
or even typical symptoms, the health insurance company will of course pay for the necessary examinations. In case of doubt, consult your ophthalmologist for a possible glaucoma screening! Those affected must be aware, however, that they suffer from a chronic disease and must therefore seek ophthalmological treatment throughout their lives.
Therefore it is all the more important to have a trustworthy ophthalmologist at your side. In addition to following the medication plan exactly, it is important to observe the strict rules of conduct after eye surgery. In addition, the intraocular pressure must be measured at close intervals by the ophthalmologist.
An untreated glaucoma always leads to blindness. In the treatment of glaucoma, these different therapies are applied depending on the severity of the condition: The therapy of open angle glaucoma also aims to reduce the intraocular pressure. Usually, drug therapy is the first line of treatment.
For this purpose, the treating ophthalmologist determines a patient-specific ‘target pressure’: How high may the intraocular pressure be so that glaucoma damage can be prevented in the future? Personal risk factors, existing eye damage, life expectancy and the level of intraocular pressure at the time of the glaucoma attack must be taken into account in the calculation. To lower the intraocular pressure, eye drops with different active ingredients are suitable.
These include the five conventional groups of active ingredients: Prostaglandin derivatives, beta-blockers, carboanhydrase inhibitors, sympathomimetics and parasympathomimetics. In order to check the success of a drug therapy, the intraocular pressure is controlled very precisely. The nurses in the eye clinic create a so-called ‘daily pressure profile’, where hourly changes are recorded.
Often even a night measurement is taken! If the effect of the eye drops is not sufficient, glaucoma must be operated or treated with a laser. During laser treatment, tiny points of light are shot very specifically at the trabecular meshwork of the chamber angle.
This causes the tissue to scar and shrink. This allows the narrow meshes of the trabecular meshwork to widen and the aqueous humor to drain better. Unfortunately, the duration of the effect of this method is not always long lasting.
Another possibility is the so-called ‘cyclofotocoagulation’. There is a simple principle behind this complicated expression. The aqueous humour is formed by a special cell layer in the eye, the ciliary epithelium.
This cell layer is attacked and partially destroyed (‘sclerosed’) with an infrared laser. As a result, it produces less aqueous humor and the intraocular pressure decreases. If both the medication and the laser therapy fail or offer no option, surgery on the eye can be performed as the last step.
The following procedure may seem difficult to understand for the medical layman at first:The filtration surgery creates a new outflow path under the conjunctiva. Many veins and lymph vessels run there, which can easily drain the aqueous humor. First, a small cap is cut into the sclera of the eyeball in the area of the trabecular meshwork.
Then a further opening is created directly through the trabecular meshwork, so that a connection to the anterior chamber of the eye is available. The previously prepared lid of the sclera is now placed on this opening and fixed.Thus the flow of the anterior chamber water can be throttled. Finally, the conjunctiva is closed tightly above it.
The outflowing aqueous humor can slightly bulge the conjunctiva forward. The ophthalmologist then refers to this as an oozing cushion. Although the filtration method is very successful in lowering the intraocular pressure, it is not entirely without danger.
Wound healing often causes great problems, as germs can easily pass through the opened eyeball and thus cause scarring. Therefore, metabolic inhibiting drugs such as Mitomycin C are already applied to the wound during the operation. The latest surgical techniques can lower the intraocular pressure without opening the eyeball.
The causes of glaucoma are manifold, but the common factor is an individually too high intraocular pressure. As already mentioned above, this is caused exclusively by a reduced outflow of the aqueous humor. However, even a pressure in the normal range can, under certain circumstances, lead to a glaucoma form (normal pressure glaucoma).
The cause of glaucoma has not been researched in detail, therefore the former definition of “too high intraocular pressure” was changed to “individually too high intraocular pressure”. There are many different subtypes of glaucoma (see classification), but they all have in common the obstruction of the aqueous humor outflow. If treated in time, glaucoma can be stopped or at least slowed down.
The visual field damage is irreparable (irreversible damage). The type of glaucoma is also important. While primary open angle glaucoma develops insidiously over years, an acute glaucoma attack can lead to blindness within a very short time.
Unfortunately, in congenital glaucoma, despite timely treatment, a small amount of damage is often left behind, which impairs visual acuity. In secondary glaucoma, the prognosis depends on the underlying disease and its optimal treatment. In particular, it can lead to damage of the optic nerve (optic atrophy). You can find more information on this topic under Optic atrophy.
