What is Glaucoma?
Glaucoma is the name given to a group of eye diseases in which the optic nerve at the back of the eye is slowly destroyed. The exact cause of the majority of glaucoma is not known. However, in most people this damage is associated with an increased pressure inside the eye – a result of blockage of the circulation of aqueous, or its drainage. In other patients the damage may be caused by poor blood supply to the vital optic nerve fibres, a weakness in the structural support of the optic nerve, and/or a problem in the health of the nerve fibres themselves.
Glaucoma has been nicknamed the “sneak thief of sight” because the loss of vision normally occurs gradually over a long period of time and is often only recognized when the disease is quite advanced. Once lost, this vision can not usually be recovered.
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. Worldwide, it is the second leading cause of blindness. Glaucoma affects 1 in 200 people aged fifty and younger, and 1 in 8 over the age of eighty. If the condition is detected early enough it is possible to arrest the development or slow the progression with medical and surgical means.
What are the symptoms of glaucoma?
Primary (Chronic) open-angle glaucoma is the commonest type. It has no symptoms initially but eyesight may be lost at a later stage in the disease. Damage progresses very slowly and destroys vision gradually, starting with the side vision. One eye covers for the other, and the person remains unaware of any problem until many of the optic 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 as early treatment will minimize visual loss.
Acute closed angle glaucoma is a medical emergency. If the high pressure is not reduced within hours, it can permanently damage vision. It produces sudden symptoms such as eye pain, headaches, haloes around lights, dilated pupils, blurred vision or vision loss, difficulty adapting to darkness, red eyes, nausea and vomiting. These signs may last for a few hours, then return again for another round. Each attack takes with it part of the field of vision.
How is Glaucoma diagnosed?
A careful examination of the eye, supplemented with specific testing of both the optic nerve function and assessment of optic nerve structure may be used to diagnose glaucoma.
A work up for glaucoma may include:
- Visual acuity
- Slit lamp examination
- Retinal examination (stereoscopic optic nerve examination)
- Intraocular pressure measurement by tonometry
- Central corneal thickness measurement
- Visual field measurement
- Optic nerve scan (OCT, GDx, HRT)
How can Glaucoma be treated?
Currently, there is no cure for glaucoma, but treatment can control the progression of the disease. The primary goal of treatment is to prevent further damage to the eye by lowering intraocular pressure and to ultimately prevent blindness. Treatment of glaucoma may include medications, surgery, or a combination of both.
For open angle glaucoma, topical eye medications (eye drops and gels) are often used early in the disease followed by oral medications or surgery. Surgery is usually reserved for individuals who do not experience adequate lowering of intraocular pressure with medications or in individuals who experience unwanted side effects from using medications.
For closed-angle glaucoma, laser surgery is an option to add to the effect of prescribed medications, especially where intraocular pressure is not adequately lowered. But glaucoma medications may also be given after surgery.
There are several types of topical medications that are used for the treatment of glaucoma. These medications work to lower intraocular pressure by either decreasing the amount of aqueous fluid the eye makes or by helping the aqueous fluid drain from the eye. The topical eye drops or gels may cause burning, stinging, or redness when instilled into the eye, although these side effects are usually tolerable. If you have problems using one topical eye medication, tell your eye doctor because using a different drug or dosage may be possible. Medications can be taken by mouth when topical eye medications are not effective at controlling or reducing intraocular pressure in some instances, but are not commonly prescribed.