Glaucoma affects roughly 400,000 Canadians
January is National Glaucoma Awareness month.
Educating yourself about glaucoma and understanding the many risks associated with it is an important step to help protect and preserve your eye health.
What is Glaucoma
Glaucoma is a group of eye diseases that progressively degenerate the optic nerve, leading to loss of nerve tissue and potential blindness. The cause of these diseases is not entirely known, though some theories point to inadequate blood supply or poor perfusion. Resulting in fluid buildup and increased intraocular pressure (IOP) in the eyes.
The pressure damages the eye’s optic nerve function, which can result in visual field loss or blurry vision. The vision loss will usually first appear in the peripheral vision, a warning sign that Glaucoma may be present or on the horizon. A routine eye exam can usually determine if you are predisposed to Glaucoma, steps you can take to prevent and/or treat it.
Four types of glaucoma
Primary open-angle glaucoma:
The most common form of glaucoma, is when pressure is placed on the optic nerve. Aqueous fluid is produced inside the walls of the eye, but if too much of it is being produced within the eye or is not draining properly, it can create unwanted pressure.
Angle-closure glaucoma:
This type is caused when the drainage angle in the eye formed by the cornea and the iris closes or becomes completely blocked. As you age, the drainage angle between the cornea and the iris are shut off or blocked creating the buildup of eye pressure and fluid.
Secondary glaucoma:
This type of glaucoma can occur as the result of an injury, eye surgery, infection, or tumour growth in or around the eye, causing pressure to rise. It has also been linked to a variety of medical conditions, medications, and eye abnormalities.
Normal-tension glaucoma:
In normal-tension glaucoma, optic nerve damage occurs despite normal eye pressure.
Risk Factors
While glaucoma can happen to anyone, here are some common risk factors that can contribute to the diagnosis:
Being over 60 years old
A family history of glaucoma
Medical conditions, such as diabetes, heart disease, high blood
Pressure, or sickle cell anemia
Corneas that are thin in the centre
Eye injuries
Being extremely nearsighted or farsighted
Taking corticosteroid medications (like eye drops) for a prolonged period
Diagnosing Glaucoma
A routine eye exam can usually determine if you are predisposed to Glaucoma. At FYidoctors, our optometrists have advanced diagnostic imaging tools for Glaucoma testing and diagnosis, including:
Ophthalmoscopy: Eye drops are used to dilate the pupil. The doctor is then able to examine the optic nerve more clearly to determine if there is damage.
Retinal Imaging: Similar to ophthalmoscopy, the goal is to view the optic nerve. In this case, laser scanning is utilized to form a fuller picture of the back of the eye. At FYidoctors, we use the Optomap Retinal Scanner during eye exams, for comprehensive digital imaging.
Tonometry: This is a pressure test of the eye. Drops are used to numb the eye and a tool is carefully placed on the outside of the eye, which gives a pressure reading. Average pressure is 16 mm Hg, and although anything higher is not necessarily an indication of glaucoma, it is a possible sign, which optometrists will analyze. Non-contact tonometry (an air puff test) is also an option.
Perimetry: A computerized visual field test in which the patient stares straight ahead and must identify lights that appear in their periphery.
Gonioscopy: This test directly looks at the drainage system of the eye. Doctors will numb the eye and place a special lens on the exterior to examine the frontal area closely.
Optical Coherence Tomography (OCT): A special type of imaging of the optic nerve and macula. OCT gives doctors precise information about potential damage to the nerve fibre layer of the retina that concerns glaucoma.
Treating Glaucoma
Although there is no cure for glaucoma, treatment and prevention protocols do exist to prevent further damage and vision loss. Treatment typically is offered in one of two ways—medication or surgery.
Beta Blockers: The most common beta blocker used is timolol. These drugs reduce production of aqueous humor (fluid in the eye), which will lower pressure.
Alpha Agonists: Those who use alpha agonists will apply it to the eye to decrease aqueous humor productions and increase the outflow of liquid from the eye. Both activities lower IOP. An example of an alpha agonist is brimonidine.
Carbonic Anhydrase Inhibitors: Common CAIs are brinzolamide or dorzolamide. They are applied to the eye and will also decrease the production of aqueous humor.
Miotics: A common miotic is pilocarpine. This particular medication increases outflow of liquid and decreases IOP.
If medication is unsuccessful, doctors may recommend that a patient should consider having surgery. A routine eye exam is the best way to determine if you are predisposed to Glaucoma, steps you can take to prevent and/or treat it.