This is the third in a series by the Lion’s Club to promote eyesight and White Cane Week.
What is glaucoma?
Glaucoma is the diagnosis given to a group of ocular conditions that contribute to the loss of retinal nerve fibers with a corresponding loss of vision. Glaucoma therefore is a disease of the optic nerve, the nerve bundle that carries images from the eyes retina to the brain.
The eyeball is basically a rigid sphere filled with fluid. As the total amount of fluid within the eye increases, so does the pressure, similar to over inflating a tire.
Many people know that glaucoma has something to do with increased pressure inside the eye, the higher the pressure inside the eye, the greater the chance of damage to the optic nerve.
Glaucoma is said to be one of the leading causes of blindness in people over the age of 40. It affects about two per cent of that population. Loss of peripheral (vision off to the side) is the earliest symptom.
Left untreated, the field of vision will continue to narrow leading to tunnel vision. If detected early, loss of vision can most often be prevented
Who is at risk for glaucoma?
High pressure alone does not mean that you have glaucoma. Your eye care provider puts together many kinds of information to determine your risk for developing this disease. The most important risk factors include:
Age, near-sightedness, African ancestry, a family history of glaucoma, past injuries to the eyes; a history of severe anemia or shock. Your eye care provider will weight all of these factors before deciding whether you need treatment for glaucoma, or whether you should be monitored closely as a glaucoma suspect.
This means your risk of developing glaucoma is higher than normal, and you need to have regular examinations to detect the early signs of damage to the optic nerve.
How is glaucoma treated?
As a rule, damage caused by glaucoma cannot be reversed. Therefore, the goal in the management of glaucoma is to reduce the intraocular pressure to the point whereby the remaining healthy nerve fibers are able to receive proper nourishment and therefore maintain function.
Common types of glaucoma
Open Angle Glaucoma– The most common type of glaucoma, known as chronic open angle or primary open angle, occurs when the canals draining the eye of aqueous humor become clogged. This blockage can gradually increase pressure within the eye to damaging levels. No pain occurs so individuals are usually unaware these changes are occurring. There are no early sings or symptoms but over the years vision will be lost starting in the periphery and moving toward the central vision.
With early treatment, you can often protect your eyes against serious vision loss and or blindness. Periodic eye examinations from your eye care provider are the best method for early detection of glaucoma. Over 90 per cent of adult glaucoma patients have this type of glaucoma. This affects about 3 million Americans-half of who don’t know they have it.
Closed Angle Glaucoma- When eye pressure builds up rapidly, it is called acute angle-closure glaucoma. This type of glaucoma commonly occurs in individuals who have narrow anterior chamber angles. In these cases, aqueous fluid behind the iris cannot pass through the pupil thus pushing the iris forward, preventing aqueous drainage through the angle. It is as though a sheet of paper floating near a drain suddenly drops over the opening and blocks the flow out of the sink. In cases of acute angle closure glaucoma, one may experience blurred vision, halos around lights, deep pain behind an eye, nausea, and vomiting. If you have any combination of these symptoms, call your eye care provider immediately. If pressure within the eye is not immediately relieved, blindness may result in a matter of days
Eye Drops
Glaucoma is usually controlled with eye drops taken several times a day; proper eye drop, sometimes in combination with pills.
These medications are used to prevent damage to the optic nerve by decrease eye pressure, either by slowing the production of aqueous fluid within the eye or by improving the flow leaving the eye.
Recently there have been a few brand new medications, which show great promise for more effectively and it is important to tell all of your doctors about the eye medications that you are using for glaucoma control.
In order for these medications to work, you must take them regularly and continuously as they were prescribed. Quite simply, the key to the success of medication therapy is patient compliance
How is glaucoma detected?
Most people think that they have glaucoma if the pressure in their eye is high, this is not always true.
High pressure only puts you at risk for glaucoma. It may not mean that you have the disease. Whether you get glaucoma depends on the level of pressure that your optic nerve can tolerate without being damaged.
This level is different for each person. Although normal pressure is usually between 12-21 mm Hg, a person might have glaucoma even if the pressure is in this range. That is why regular eye examinations are so important.
There are several tests your eye care provider may perform to confirm a diagnosis of glaucoma.
Since a large percentage of glaucoma sufferers do indeed have elevated intraocular pressure, careful measurement of the eye pressure on a regular basis (for high risk people) is a crucial step in early detection. This pressure is measured using an instrument called a tonometer.
This standard test determines the fluid pressure inside the eye. There are many types of tonometry. The most common type called application tonometry uses a blue light to measure pressure.
Another type is the air puff tonometer, which measures the resistance of the eye to a puff of air to determine pressure.
Ophthalmoscopy – The back of the eye can also be observed directly through an eye microscope or ophthalmoscope. This is to insure that the optic nerve is healthy.
Perimeter – This test measures your side (peripheral) vision. It helps your eye care professional find out if you have lost side vision, an early sign of glaucoma.
Patient responsibility – Treatment for glaucoma requires a team made up of both you and your provider can prescribe treatment for glaucoma, but only you can make sure you take your eye drops or pills.
Never stop taking or change your medications without first consulting your eye care provider.
Periodic eye examinations and tests are critical to monitor your eyes for any changes because glaucoma can worsen without your being aware of it.
Your eye care provider will schedule frequent short exams in which they will monitor the pressure within the eye.
Remember, regular eye exams may help prevent unnecessary vision loss.
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