Glaucoma derives from the Greek word glaukós, meaning “clear”
Glaucoma is a group of diseases. It commonly develops slowly, over several years, without giving any symptoms. In the beginning, you may not even notice something is wrong, as the condition usually starts with unnoticeable blind spots on the outer (peripheral) field of vision - typical for the most common form, open-angle glaucoma. Glaucoma has already advanced quite far by the time you notice any defects, with vision gradually failing. If this happens, please consult an ophthalmologist as soon as possible, as this condition can lead to blindness.
Although glaucoma usually affects both eyes, it may not affect them equally. The better eye may compensate for a while, if the other one starts to lose patches of visual field.
Glaucoma is the most common cause of irreversible loss of vision in the world. It affects the optic nerve connecting the eye to the brain (back portion of the interior of the eyeball). Damage very often occurs when the intraocular pressure (IOP) – the main risk factor for glaucoma – is too high. This happens, when the drainage of the aqueous humour, a watery fluid that fills the space between the cornea and lens and maintains the normal pressure in the eye, is blocked. There are at least 50 different types of glaucoma.
Eye pressure can vary hourly, daily and weekly and is dependent on many factors. A statistically normal pressure varies between 10 and 21 mm Hg (millimeters of mercury, a scale for recording the internal eye pressure). A slightly elevated eye pressure (22-30 mmHg) does not necessarily cause any defects in the visual field. But if your IOP is over 30 mmHg, the risk of glaucoma is 40-fold. In general: the higher the pressure, the more risk to the optic nerve. However, the eye pressure of some glaucoma patients is below 21 mmHg. In other words, tolerance of an individual to the changes in pressure varies individually.
Age: every decade of your life doubles the risk of glaucoma (glaucoma is most common in elderly people over 60 years and it rarely occurs in people who are younger than 40)
Family history: if glaucoma occurs in your family, you are 3 to 9 times more likely to get glaucoma
The so called exfoliation syndrome, which is common in the Nordic Countries (grayish flakes on the surface of the lens, which can be detected by an ophthalmologist with a microscope)
Near or short-sightedness (myopia): if you have myopia of over -3 diopters the risk of glaucoma is two-to three-fold
Race: If you are of African or Afro-Caribbean origin you are about 5 to 6 times more likely to get glaucoma than Caucasians
Certain other diseases: diabetes, artherosclerosis (hardening of the arteries), and hypertension (high blood pressure) may impair your blood flow in the eye and exposure to glaucomatous defects.
when you reach 40 years old
when you are 40 to 60 years old, every 5 years
when you are over 60 years old, every 2 to 3 years
To detect glaucoma, your doctor will examine your eyes with a special microscope, the so called slit lamp, providing a magnified, three-dimensional view of the structures within the eye. When used in combination with special lenses the back of your eye, where the optic nerve head is located, can be viewed. In someone with glaucoma, there are specific changes that can be seen in this area.
Your ophthalmologist will also measure the eye pressure as well as the thickness of your cornea, as this can affect your intraocular pressure reading. He will also test the angle where your iris meets the cornea via gonioscopy. In addition your field of vision may also be examined using a test called perimetry.
If the diagnosis is glaucoma, a pressure-lowering treatment is usually started.
If the pressure is high, but there are no signs of glaucoma, it is either possible to observe the situation without starting treatment or start prophylactic treatment. In any case, the decision should always be taken individually by the ophthalmologist.
Treating glaucoma is based on lowering the intraocular pressure. The aim is to slow the progression of your disease. Unfortunately vision already lost cannot be restored. The choices of treatment are usually in the following order:
Medicines (eye drops)
The medicinal treatment of glaucoma normally lasts for the rest of your life. For long-term treatment you should consider preservative free eye drops to ensure optimal tolerability of the medication. Medications work either to reduce the amount of aqueous humour (e.g. beta-blockers) or increase the drainage of aqueous humour (e.g. prostaglandin analogue drops). It is essential that you use the medicine as advised by your doctor, because it helps, if only used properly.
As an alternative, laser treatment (laser trabeculoplasty) of the chamber angle aims at improving the outflow of the aqueous humor, in order to decrease the pressure - at least for a few years. If despite medical or laser therapy glaucoma progresses, surgical treatment may be used.
The most common form of glaucoma surgery is trabeculectomy. This is a procedure to relieve intraocular pressure by removing part of the eye's trabecular meshwork and adjacent structures. It allows drainage of aqueous humor from within the eye to underneath the conjunctiva, where it is absorbed.