Glaucoma is a disease of the optic nerve. Each optic nerve is made up of a million fibres originating from the retina. In glaucoma, some of these nerves become damaged. The eye’s aqueous fluid is constantly produced and drained at a balanced rate to ensure the health of the lens and cornea. When the drainage becomes blocked, intraocular pressure can increase and open-angle glaucoma occurs.
This damage will initially cause blind spots in peripheral or side vision and if left untreated further nerve damage will occur and cause shrinkage of the field of vision, leading to tunnel vision, and eventually blindness. Fortunately blindness rarely occurs if glaucoma is treated early.
How does glaucoma occur what are the glaucoma causes?
In most patients the main glaucoma cause is due to an increased pressure inside the eye—a result of blockage of the circulation of aqueous, or its drainage.
In other patients the glaucoma cause may be due to poor blood supply to the vital optic nerve fibres, a weakness in the structure of the nerve, and/or a problem in the health of the nerve fibres themselves.
Types of glaucoma
Chronic, or primary open angle glaucoma, is by far the most common type of glaucoma, however other forms can occur:
Low-tension or normal tension glaucoma – Occasionally optic nerve damage can occur in people with apparently normal eye pressure. This form of glaucoma is treated in the same manner as open-angle glaucoma.
Acute (angle-closure) glaucoma –This occurs due to a sudden blockage of the drainage canals in the eye resulting in a rapid build up of pressure within the eye. This increased pressure can cause blurred vision, nausea, coloured halo’s around lights, headache and severe pain. This is an emergency situation as the rapid increase in pressure can severely damage the optic nerve in a matter of hours. Usually, YAG laser surgery performed promptly can clear the blockage and protect against visual impairment.
Congenital glaucoma – This is a rare form of glaucoma caused by an abnormal drainage system. It can exist at birth or develop later in life. Early signs might be sensitivity to light, enlarged and cloudy eyes, and excessive watering. Surgery is usually needed.
Secondary glaucoma’s – Secondary glaucoma’s can develop as a result of other disorders of the eye such as injuries, cataracts, eye inflammation. The use of steroids (cortisone) has a tendency to raise eye pressure and therefore pressures should be checked frequently when steroids are used.
Chronic (primary open-angle) glaucoma is the most common type. It has no symptoms until eye sight is lost at a later stage. Damage progresses very slowly and destroys vision gradually, starting with the side vision. One eye compensates for the other, and the person remains unaware of any problem until a majority of nerve fibres have been destroyed, and a large part of vision has been lost. This damage is irreversible. It is progressive and usually relentless. Treatment cannot recover what has been lost. But it can arrest, or at least, slow down the damage process. That is why it is so important to detect the problem as early as possible, to be able to start treatment with as little damage to the vision as possible.
How is glaucoma detected?
Your eye specialist will suspect glaucoma if the pressure in your eye is abnormally high or if the optic nerve appears abnormal. A glaucoma test usually includes:
- An optic nerve check with an ophthalmoscope
- An eye pressure check (tonometry)
- A visual field assessment if needed – this tests the sensitivity of the side or peripheral vision, where glaucoma strikes first.
Regular eye examinations are the best way to detect glaucoma early.
Glaucoma treatment options
Although there is no cure for glaucoma it can usually be controlled so that further damage is slowed or halted. This usually involves a life-long commitment to treatment and regular check-ups by your eye specialist.
Fortunately there is now a range of treatments options available to control glaucoma. The safest and most appropriate option will be determined by your eye specialist based on your individual needs and the type of glaucoma.
Glaucoma treatment options include:
- Eye drops – The most common form of treatment. To be effective eye drops must be used regularly and continually. There is a range of drops currently available which all function slightly differently, all with the aim of lowering the pressure in the eye thereby slowing the progression of the glaucoma. They will be prescribed by your eye specialist based on the type of glaucoma you have and your individual needs.
- SLT (Selective Laser Trabeculoplasty) – Laser trabeculoplasty is a relatively minor procedure in which some of the blockages to the drainage canals are opened. Laser trabeculoplasty is generally performed when eye drops have been unable to slow the deterioration in the field of vision. Laser trabeculoplasty is performed under local anaesthetic and does not require a hospital stay. Often eye drops may need to be continued after laser.
- Surgery – Glaucoma surgery involves the creation of a new channel for the fluid to drain out of the eye. It is usually effective in reducing pressure in the eye and in some cases no further medication is needed after surgery. Glaucoma surgery is generally only performed after eye drops and Laser trabeculoplasty have been unable to control the eye pressure.
Should I get checked for glaucoma?
Over 300,000 Australians have glaucoma. While it is more common as people age, it can occur at any age. As our population becomes older, the proportion of glaucoma patients is increasing.
Everyone over the age of 40 should be checked for glaucoma at least every five years, and those with a family history more frequently. If you have any of the above glaucoma symptoms it is advisable to get a check-up.
If you have a parent with glaucoma your chances of contracting glaucoma are increased significantly. Make an appointment with one of our experienced ophthalmologists for a check up now.
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