More information about glaucoma
The spherical shape of the eye is also maintained due to that within the eye fluid is produced, which is called chamber water. This eye fluid has nothing to do with the external tear fluid. The amount of the eye pressure is dependent on the balance between production and drainage of the chamber water. Too high eye pressure may arise when the outflow of chamber water is obstructed.
The mechanism, which is caused due to glaucoma leads to damage of the optic nerve, is still not known in detail. However there are many factors known to significantly increase the probability of the occurrence of glaucoma .
- Increased eye pressure: this is by far the most important risk factor. A statistically normal eye pressure is situated between 11 and 21 mmHg. The higher the intraocular pressure, the greater the likelihood of glaucoma. However, the majority of people with an intraocular pressure above 21 mm Hg will not have glaucoma.
- Glaucoma in the family: if glaucoma occurs in one's family (1st or 2nd tier), the risk of glaucoma is nearly 10 times higher than for someone without glaucoma in the family.
- Old age: with age glaucoma becomes more common (4% of people aged over 80 have glaucoma).
- Strong myopia or farsightedness.
- Colored people are more likely to get glaucoma.
- Deviations from the blood vessels around or in the eye.
Types of glaucoma
Glaucoma is common; 1.5% of the Dutch population over age 40 has glaucoma. Glaucoma is classified into primary and secondary glaucoma. Primary glaucoma means that it is a self-contained glaucoma disease. Secondary glaucoma arises as a phenomenon due to a different (eye) disease or as a result of certain medication or eye drops. Primary glaucoma is divided into open-angle glaucoma, closed angle glaucoma and congenital (inborn) glaucoma. The most common considering primary glaucoma is open angle glaucoma. We hereby know the high-tension glaucoma and normal tension glaucoma
When suffering from high-pressure glaucoma, the drainage system of the eye gets clogged. This increases eye pressure and ultimately affects the optic nerve damaging it and causing visual field defects. In normal tension glaucoma other risk factors play a role such as blood flow in the vessels probably being more important than the eye pressure that isn’t increased. Also, this kind of glaucoma leads to damage of the optic nerve and visual field loss. When closed-angle glaucoma is the construction of the eye is in such a way that due to the iris, the drainage system of the eye can become blocked, causing the fluid in the anterior chamber not being able to escape and causing the eye pressure to increase. This form of glaucoma may be acute or chronic. The acute form is usually associated with blurred vision, red eye, headache, nausea and vomiting. The eye pressure being very high causes these symptoms and a prompt treatment is required to prevent damage to the optic nerve. The chronic form is more common and is in early stage treatable. People, who are farsighted, with strong plus glasses, have a greater risk of this type of glaucoma.
Diagnostics to glaucoma
It would be ideal if everyone older than 40 years could be screened for glaucoma. However, only the eye pressure is measured, not all glaucoma patients discovered in this investigation. As the list of risk factors makes clear, in glaucoma many more factors play a part than just the eye pressure. So, in addition to the measurement of the eye pressure it should include checking the optic nerve, and, if necessary, a visual field examination is carried out. Oogziekenhuis Eindhoven also has more sophisticated measurement equipment, such as the Optical Coherence Tomography. This instrument scans in a few seconds, the optic nerve, and provides information on the existence or non-existence of 'glaucomatous' damage to the optic nerve. If after this diagnostics is suspected glaucoma, our ophthalmologist determines together with the patient whether and how it is treated. A glaucoma patient should be monitored for life.
Treatment of glaucoma
At this time, the only proven therapy for glaucoma is to reduce eye pressure. If the eye pressure is reduced sufficiently, a further increase in visual field defects can be prevented. However, existing visual field defects cannot be undone. Therefore it is important that glaucoma is detected in its earliest stage. However, not all people are treated with an elevated eye pressure. There are people with a (moderately) increased eye pressure only. These people do not have glaucoma but ocular hypertension. A treatment is then unnecessary, good control is, however, necessary. Depending on the presence of other risk factors for glaucoma, the ophthalmologist will discuss with you how often check up for the eye pressure is needed. On the other hand there are also people with normal eye pressure (<22 mmHg), which do have optic nerve damage. These people have glaucoma and should be treated (normal pressure glaucoma). As with the therapy usually there is a first choice for treatment with eye drops. There are many different types of eye pressure reducing drops. The ophthalmologist will chose the eye drops which cause a maximum eye pressure lowering effect with minimal side effects.
It is important that the patient applying the drops (one or more times per day) makes a habit of it so that no droplets are forgotten. The technique of the drops can cause problems in the beginning. The patient should continue dripping until he feels a drop in the eye. If applying the drops remains difficult than the patient could possibly use a tool, which is available at the pharmacy. If eye drops do not achieve a sufficient reduction in eye pressure, laser treatment may be carried out with some patients. Here, the drainage of the eye fluid by means of laser light is made wider. Lastly, also an eye tension lowering operation can be carried out. One speaks of a filtering surgery or trabeculectomy. In this operation, a hole in the wall of the eye is made. The inner eye fluid then receives an additional outflow.. Finally, when eye drops, tablets, optionally, a laser treatment and a trabeculectomy there is not enough in order to succeed in lowering the pressure in such a way that the visual field defects remains stable, there also can be chosen for a glaucoma implant. An extra drainage system is also surgically created where also to some extent the size of the drainage can be determined in advance.