The layman’s term for glaucoma is “tunnel vision”, as the loss of peripheral vision is a common symptom of glaucoma. Glaucoma damages the eye’s optic nerve and destroys the nerves within the retina. Untreated, glaucoma can result in vision loss and blindness. Predominant therapies are treatments with medical eye drops.
What Is Glaucoma?
Up to 4 % of people in Germany are affected by glaucoma in the course of their lives. However, the number of unreported or undiagnosed cases is suspected to be much higher. Worldwide, up to 70 million people suffer from glaucoma.
Glaucoma is defined as a loss of retinal nerve cells along with the nerve fibres, resulting in a loss of the field of vision. The development of the damage is caused by several factors:
In most cases, fluid drains too slowly from the anterior chamber of the eye, resulting in a fluid buildup. This leads to an increase of pressure inside the eye, which slowly damages the nerve fibres of the optic nerve. As a result, the patient slowly goes blind.
An increased intraocular pressure (that is, the pressure inside the eye) does not necessarily spell glaucoma. Likewise, even a very slight increase in intraocular pressure which would still be considered normal (up to 22 mm Hg) could cause minor damage in certain circumstances. Glaucoma can even develop without increased eye pressure. The so called normal-tension glaucoma (also called low-tension glaucoma) is a condition in which damage occurs despite absolutely normal intraocular pressure. Here, the perfusion of the eyeground is disrupted to such an extent that the optic nerve perishes over a period of time.
Congenital glaucoma is a very rare form of hereditary glaucoma affecting very young children.
Types of Glaucoma
There are several types of glaucoma, distinguished by the cause of the disease:
The most common type of glaucoma is the so-called primary open-angle glaucoma, also known as wide-angle glaucoma. The eye pressure is increased (usually between 25 and 40 mm Hg), even though the angle where the cornea and iris meet is open which ought to allow drainage of the eye fluid.
Normal-tension glaucoma (or low-tension glaucoma) is characterized by a disturbed blood flow in the smallest blood vessels of the eye (microcirculation) despite normal eye pressure, causing damage to the optic nerve.
If the angle between iris and the cornea is too narrow or compromised by adhesion or intergrowths, fluid drainage is compromised, which can cause a buildup of pressure in the eye in chronic angle-closure or narrow-angle glaucoma.
In acute cases of angle-closure or narrow-angle glaucoma, a sudden buildup of pressure in the eye to very elevated levels usually causes strong pain, blurred vision and other visual disturbances. The affected eye may also be reddened. Such an acute attack of glaucoma is an emergency which has to be treated immediately by an ophthalmologist to avert damage to the eye.
Primary congenital glaucoma is often caused by a lack of proper development before birth of the network of tissue which is responsible for the draining of fluid from the eye (or trabecular meshwork). Again, early diagnosis and treatment are very important to avoid further damage to the eyes.
Secondary glaucoma refers to any form auf glaucoma with an identifiable cause (e.g. injury, infection, tumours, certain drugs).
Which Signs Might Herald Glaucoma?
Glaucoma is hardly noticed ahead of time, as there are no initial symptoms. Most forms of glaucoma do not cause any pain. Glaucoma can destroy vision before any signs or symptoms are apparent. In any case, headaches or a slight visual disturbance should be a reason for a checkup by an ophthalmologist.
Checkups Are Important!
You should make use of voluntary checkups at the ophthalmologist. Glaucoma does not exclusively develop from the age of 40 years, but can also occur in younger people.
Risk factors for glaucoma are
Family history of glaucoma
Cardiovascular disease (e.g. high blood pressure)
Moreover, people suffering from migraines or sleep apnoea are disproportionately affected by glaucoma.
How Is Glaucoma Diagnosed?
The ophthalmologist carries out various examinations to diagnose glaucoma. The eye pressure will be measured, but the key to detection is an examination of the optic nerve head.
An ophthalmological examination includes eye pressure measurement and a visual acuity test. An examination of the interior surface of the eye (the ocular fundus) with an assessment of the optic nerve head is essential. The field of vision can also be tested if previous examinations provided an indication of glaucoma.
It is typical for glaucoma that the central vision is conserved for a long time despite considerable losses of the field of vision near the visual centre. These field losses can be compensated for by the vision field of the unaffected eye. For this reason, glaucoma is initially hardly noticed in everyday life, which makes it all the more dangerous.
Further specialized examinations can follow, such as the measurement of eye blood vessel width and the photographic documentation of the optic nerve head.
Glaucoma Treatment Options
The treatment of glaucoma aims to lower the eye pressure. However, an improvement of the microcirculation (and therefore, the perfusion of the eye) is equally as important.
The major focus in the treatment of the various forms of glaucoma is usually a drug therapy. Several active compounds are used. These include:
Eye drops which constrict the pupils, thereby allowing the aqueous fluid to drain
Drugs such as beta blockers which reduce formation of aqueous fluid, hereby lowering eye pressure
Further drugs such as prostaglandins and carbonic anhydrase inhibitors and various combination drugs expand the therapy range. Glaucoma drug therapy
Surgery or laser treatment might be the therapy of choice in some cases. However, the best treatment for each individual patient can only be identified in consultation with an ophthalmologist.
It is important to note that the treatment has to be applied regularly and without fail. Only regularly applied eye drops can protect against blindness. Adhere to the treatment recommendations of your medical practitioner and immediately consult an ophthalmologist should problems or questions arise.
What You Can Do
A healthy lifestyle along with regular physical exercise and a balanced diet (including as often as possible radical scavengers contained in vegetables such as broccoli, spinach, tomatoes, tofu and lettuce) benefit not only your eyes.