Green Star

Green Star: Description

A glaucoma (glaucoma) refers to a group of eye diseases that, in an advanced stage, damage the nerve cells of the light-sensitive retina (retina) and the optic nerve (optic nerve). The name of the disease has nothing to do with the avifauna. The old term “green star” describes on the one hand the frequently observed (blue) greenish shimmering of the iris in advanced glaucoma, on the other hand the “rigid look” when the eye is blind.

This is how Green Star is made

In the majority of cases, Green Star is associated with increased pressure in the eyeball. This arises when in the anterior chamber, where the eye lens is located, more aqueous humor is formed than can be derived via the drainage system in the chamber angle. The constant exchange of aqueous humor is important for the function of the eye. The aqueous humor carries nutrients and oxygen to the lens and the cornea, which do not have their own blood vessels. In addition, the aqueous humor serves as an optical medium. If it accumulates in the anterior chamber, the pressure in the eye increases.

The intraocular pressure is measured with a so-called applanation tonometer. The device determines how much pressure is needed to deform a specific area of ​​the arched cornea of ​​the eye (the clear skin layer in front of the pupil). The higher the intraocular pressure, the higher the force that must be expended. The unit of measurement for the pressure in the eyeball is “millimeters of mercury” (mmHg), the same unit that is also used, for example, for blood pressure. Normal values ​​for intraocular pressure are between 10 and 21 mmHg and can fluctuate by about five mmHg during the day – the highest values ​​occur at night and early in the morning. In glaucoma, the pressure in the eyeball can increase to values ​​of 40 to 60 mmHg.

Due to the increased pressure in glaucoma the blood supply and nutrition of the sensitive nerve cells are disturbed. Visual disturbances, so-called visual field defects, are therefore among the typical signs of glaucoma. If a green star goes unnoticed or is not treated medically enough, the affected person can even lose sight.

Green cataracts can lead to blindness

Green cataract is one of the most common causes of blindness. In the industrial nations, the diagnosis “Green Star” ranks third among the causes of blindness. The Initiative for early detection of glaucoma estimates that around 800,000 people in Germany suffer from glaucoma. But only about two-thirds of the diagnosis is known – in many cases, those affected know nothing about the disease. If the affected person perceives the visual disturbances themselves, the damage to the retina and / or optic nerve is often already well advanced. If damage has already been caused by glaucoma, it usually can not be reversed.

Green cataracts are more common with increasing age. On the other side of the age of 75, seven to eight percent of people are affected; after the age of 80, a green star even hits between 10 and 15 percent.

Four basic forms of glaucoma

Green Star can occur in different forms. Ophthalmologists (ophthalmologists) divide the variants according to anatomy and glaucoma causes into four major groups:

The primary open-angle glaucoma (sometimes referred to as “wide-angle glaucoma”) arises when the outflow of aqueous humor is disturbed by plaques. Open-angle glaucoma is the most common form of cataract in the elderly. The Normal tension glaucoma is a subtype of open-angle glaucoma in which, however, the outflow of aqueous humor is not disturbed and thus the pressure in the eyeball is not increased abnormally.

In narrow-angle glaucoma, the anterior chamber of the eye – usually due to the condition – is so shallow that the iris’s iris deepens or even blocks the angle of the chamber. This happens especially when the pupil is dilated by darkness or by the action of drugs (or drugs) and the iris in the chamber angle “unfolds”. The outflow of aqueous humor is thus impeded or even completely prevented (Angle closure glaucoma), If this outflow disorder occurs by accident, it manifests itself as Glaukomanfall – an ophthalmological emergency. The pressure in the eye can rise so much that the retina and nerves are immediately and permanently damaged.

If a green star occurs in the newborn or toddler, it is usually one primary congenital glaucoma – An incorrect development of the chamber angle, which therefore can not sufficiently dissipate the aqueous humor formed in the eye.

Secondary (“acquired”) glaucoma is called a green star, if other diseases, inflammations or injuries are responsible for the outflow disorder of the aqueous humor. For example, altered blood vessels, scarring or inflammatory cells may partially or completely block the angle of the chamber.

Green Star: symptoms

Everything important to the typical signs of glaucoma read in the article Green Star â € “Symptoms.

Green Star: causes and risk factors

A glaucoma means that the visual cells of the retina and / or the optic nerve in the eyeball have been damaged. The damage is caused by a disturbed blood supply to the sensitive cells, which leads to a lack of oxygen and nutrients.

Decisive for the development of glaucoma is not the absolute pressure inside the eye, but the difference between intraocular pressure and the pressure in the blood vessels of the retina and the optic nerve, the so-called perfusion pressure. If the pressure in the interior of the eye rises to near the perfusion pressure or even exceeds it, the fine blood vessels are literally clamped off – blood can no longer flow.

Recent studies have shown that only about half of people with glaucoma actually have an abnormally high intraocular pressure. In about 50 percent of those affected, the intraocular pressure is thus below the critical limit of 25 mmHg. Nevertheless, the circulation in these patients is already disturbed. Reasons for the mismatch between intraocular pressure and perfusion pressure are therefore not always flow obstruction for the aqueous humor, but possibly also changes in the blood vessels or disorders of the general circulatory function.

The most important glaucoma causes at a glance:

• deposits, so-called plaques, the outflow of aqueous humor in the fine mesh of connective tissue trabeculae (Trabecula) and the “Schlemm’s channel” in the chamber angle (primary open-angle glaucoma) prevent. The most important “risk factor” for this is a high age.
• At the Normal tension glaucoma The perfusion pressure in the blood vessels of the retina is not sufficient to overcome the normal pressure inside the eye. This creates a supply shortage in the visual and nerve cells. Triggers or risk factors are:
• Cardiovascular diseases such as coronary heart disease (CHD), heart failure, arteriosclerosis or peripheral arterial occlusive disease (PAOD) of the cerebral or cerebral veins
• generally low blood pressure or a very low second blood pressure (diastolic blood pressure), such as may occur in heart valve defects or certain disorders of vascular function (especially in the case of an additional fall in blood pressure at night)
• chronically high blood pressure (Hypertension), which damages the blood vessel wall
• chronically elevated blood lipid levels (Hypercholesterolemia), which leads to deposits in the vessels (arteriosclerosis)
• Diabetes mellitus and other metabolic diseaseswhich alter the inner wall of blood vessels and impede blood flow
• Autoimmune diseases involving blood vessels
• Smoking, as nicotine narrows the blood vessels – even those in the eye. In addition, tobacco consumption is considered an important risk factor of arteriosclerosis
• (Temporary) spasmodic constrictions of the blood vessels Raynaud syndrome, migraine or tinnitus
• severe inflammation on or in the eye, as a result of which scarring or deposits in the chamber angle (inflammatory cells, protein) may arise (secondary glaucoma)
• many years cortisone treatment
• drugs, which dilate the pupil, since the iris of the iris can block the angle of the ventricle in the case of an already flat chamber of the eye (angle-closure glaucoma)
• Strength Short or long-sightedness beyond four diopters, in which the shape of the eyeball and the anterior chamber of the eye is altered
• familial accumulation: Cases of glaucoma in the family are considered one of the most important risk factors
• black skin color: People with dark skin have a multiple increased disease risk

Green Star: examinations and diagnosis

Green cataract is damage to the optic-sensory cells in the eye or the optic nerve head located in the back of the eye. It arises when the blood flow to the cells is limited or collapses because the pressure difference between the blood vessels and the eyeball is not large enough. Therefore, studies of blood supply and pressure conditions in the eye are among the most important diagnostic measures in glaucoma. In addition, the condition of the retina and optic nerve head and the outflow conditions for the aqueous humor are of importance for the diagnosis of “cataracts”. The most important glaucoma examinations:

Intraocular pressure measurement (tonometry)

The pressure in the eyeball can be measured quickly with the so-called applanation tonometer. The measuring plate of the device presses on the cornea of ​​the eye (in the area of ​​the pupil) from the front and determines the pressure necessary to deform a defined area (applanation = flattening, flattening, tone = tension, pressure). Since the cornea of ​​the eye is very sensitive to touch, it is anesthetized for examination with a local anesthetic. The unit of measurement for the intraocular pressure is “mmHg” (millimeters of mercury), the upper limit for a normal pressure in the eye is 21 mmHg. In glaucoma, the majority of those affected are above this value, in extreme cases (glaucoma) sometimes even more than twice as high. In older people, the pressure in the eye is often higher, without this necessarily means that a green cat is present. The measurement result is also influenced by the thickness of the cornea, which should therefore be determined by further examination.

Slit lamp examination

The slit lamp is probably the most important diagnostic tool of the ophthalmologist. With it, he can direct a sharply limited beam of light to the eye. Depending on the bundling and direction of the light beam, different structures are visible or particularly highlighted. Microscopes can be used to detect even the finest changes – for example, the cornea, the anterior chamber of the eye and the angle of the chamber, the lens of the eye, but also the retina. The slit lamp examination takes place in a darkened room and is completely painless for the patient. When suspecting glaucoma, the ophthalmologist assesses, in particular, the space available for the anterior chamber angle and the depth of the anterior chamber of the eye. He also looks for changes in the iris or unusual corneal pigmentation.

Examination of the chamber angle

If the suspected diagnosis “Green Star”, with the so-called Gonioscopy the chamber angle examined. He is usually not visible from the outside because of its peripheral position in the anterior eyeball. With a special lens, the ophthalmologist can “see around the corner”. He places the gonioscope directly on the previously locally anesthetized cornea. A shallow angle of the chamber (narrow-angle glaucoma), drainage obstruction through the iris and possible age-related plaques (for example in open-angle glaucoma), adhesions and discolorations may indicate glaucoma.

Visual Fields

An important investigation to detect already existing retinal or nerve damage is the visual field measurement (perimetry). During this examination, the patient is successively presented with visual stimuli at different locations in the room without being allowed to direct his gaze directly to them. The perception of these stimuli, their location and their strength are recorded. The outline and possible failures in the visual field allow conclusions about possible disorders of the visual cells or nerve tracts. However, cataract is not the only cause of a restricted field of vision. In addition, visual field defects (scotoma) occur in glaucoma usually late when more than 30 percent of the nerve fibers are damaged.

Ophthalmoscopy

With a reflection of the ocular fundus (ophthalmoscopy), the ophthalmologist can assess the condition of the retina, its blood vessels and the optic nerve head. The ophthalmoscope is a mixture of magnifying glass and light source. In order for the doctor to be able to observe as large a section of the fundus as possible, the patient receives special pupil-dilating eye drops shortly before the examination. Ophthalmoscopy is particularly revealing for the diagnosis of “green star”, because with this examination, glaucoma damage and the stage of the disease are directly visible.

Measurement of blood flow

Various examinations can determine the blood flow to the retina and the optic nerve. Commonly used procedures are fluorescence angiography (X-ray contrast examination of the blood vessels in the eye), thermography (recording the heat output of the eyeball as a measure of blood flow) or capillary microscopy (viewing the finest retinal blood vessels in magnification). Since the relationship between intraocular pressure and the pressure in the blood vessels of the eye is not correct in glaucoma, also a blood pressure measurement is one of the routine examinations.

Regular checks

In people with pre-existing glaucoma or known risk factors for cataracts (for example, narrow angle, age over 40 years, family cataracts, black skin, diabetes mellitus, Raynaud’s syndrome or long-term use of certain medications), regular check-ups at the ophthalmologist are particularly important. Only then can the ophthalmologist recognize threatening eye damage early and promptly initiate appropriate treatment.

Green Star: treatment

How glaucoma is treated, read in the article Green Star â € “Treatment.

Green Star: Disease course and prognosis

Without treatment, green cataracts lead to blindness because it damages the visual cells of the retina and the optic nerve more and more. The disease accelerates the longer it persists. It is important to know that once incurred damages are irreversible.

It is therefore all the more important to recognize glaucoma at an early stage, to avoid risk factors and to consistently continue the treatment that has begun. The good news is that you can stop green star and maintain your vision with suitable medication or surgery. Often, medications can reduce the intraocular pressure in glaucoma sufficiently.