What is glaucoma?
Glaucoma is a chronic progressive eye disease characterized by a degeneration of the optic nerve. This can lead to serious vision loss if not detected and treated early. The optic nerve takes all of the information the eye sees and transmits that information to the brain. Glaucoma is one of the leading causes of blindness in Canada.
What causes glaucoma?
The exact cause and mechanism of glaucoma is not fully understood. There seems to be some level of mechanical compression and/or decreased blood flow to the optic nerve. Although high pressure inside the eye is associated with glaucoma, some people can also develop glaucoma with “normal” eye pressure.
An injury, infection or tumour in or around the eye can cause the pressure inside the eye to rise, leading to a form of glaucoma. These situations are referred to as secondary glaucoma, because their cause is a result of another condition.
There are two types of adult glaucoma which are not due to these other causes. Primary open angle glaucoma is the most common type and results in slow loss of vision with no symptoms. Acute angle-closure glaucoma is less common and results in a sudden elevation of pressure and symptoms of pain, redness and nausea.
Who gets glaucoma?
Glaucoma most frequently occurs in individuals over the age of 40, and there is a hereditary tendency for the development of the disease in some families. There is also a greater risk of developing glaucoma when you have diabetes, high blood pressure or a history of eye injuries. Regular eye examinations by an optometrist are important for people of all ages to assess the presence of, or your risk for, glaucoma. Glaucoma cannot be detected without an eye exam.
Why is glaucoma harmful to vision?
The optic nerve, at the back of the eye, carries visual information to the brain. When the fibers that make up the optic nerve are damaged due to increased pressure and/or reduced blood flow to the nerve, the amount and quality of information sent to the brain decreases and a loss of vision occurs. Usually peripheral vision is affected first, followed by central vision during the later stages of the disease. Glaucoma is sometimes called a “silent disease” as it usually does not cause symptoms and the loss of vision is not noticed by the patient until the loss is quite advanced.
Will I go blind from glaucoma?
If diagnosed at an early stage, eye drops and laser treatment can control glaucoma and little or no further vision loss should occur. Note that if eye drops are prescribed, they have to be used always to control the eye pressure. If left untreated, peripheral vision is affected first, followed by central vision loss during late stages of the disease. Complete blindness may occur.
How can I tell if I have glaucoma?
Primary open angle glaucoma, which is the most common type of glaucoma, develops painlessly and gradually. There are no early warning signs and it can gradually destroy your vision without you knowing it. Regular eye exams are the only way to assess glaucoma risk and detect the presence of this form of the disease.
Acute angle-closure glaucoma is a more sudden onset type of glaucoma and may have warning signs and symptoms such as:
• Eye pain
• Red eyes
• Blurred vision
• Haloes around lights
How is glaucoma detected?
A comprehensive eye examination is the first step to detecting glaucoma. Your optometrist will perform a simple and painless procedure called tonometry during your routine eye exam, which measures the internal pressure of your eye.
They will also inspect the drainage angle inside the eye and look into your eye to observe the health of the optic nerve and measure your peripheral vision. Your optometrist will often take a detailed look at your optic nerve through a dilated pupil using a series of hand held lenses. They may also use advanced imaging devices when assessing your optic nerve.
How is glaucoma treated?
Treatment of glaucoma will depend on the type, severity and progress of the disease. It cannot be cured, but it can be controlled, often with daily eye drops. Laser surgery is also an effective way to control glaucoma and maintain your remaining vision.
In more complicated cases, surgery may be needed to completely bypass the eye’s natural drainage system. Once vision is lost due to glaucoma, it cannot be restored. This is why regular preventive eye exams with your optometrist are important.
“Glaucoma” Ontario Association of Optometrists, Retrieved 13 June 2019. <https://www.optom.on.ca/OAO/Patients/Library/Glaucoma.aspx>