Glaucoma refers to a group of eye conditions where the pressure in the eyeball damages the nerve of sight (the optic nerve) at the back of the eye.
A small structure inside the eye makes fluid to maintain normal eye pressure.
The small amount of fluid made within the eye constantly drains out through tiny channels within the eye in the "drainage angle"and drains back along small blood vessels on the eye.
This is completely different to the tears that are made by structures around the eye and that may cause watery eyes.
The eye pressure is not normally something than can be felt.
Types of Glaucoma
There are two major types of glaucoma:
Primary open-angle glaucoma
The most common type of glaucoma is called primary open-angle glaucoma. The eye does not drain fluid as well as it should (like a clogged drain). As a result, eye pressure builds and starts to damage the optic nerve. This type of glaucoma is painless and causes no vision changes at first.
This is why glaucoma is sometimes called the "thief of sight"
Some people have optic nerves that are sensitive to normal eye pressure. This means they may develop glaucoma even with normal eye pressures.
Angle-closure glaucoma (also called "closed-angle glaucoma" or "narrow-angle glaucoma")
This type happens when someone's iris is very close to the drainage angle in their eye. The iris can end up blocking the drainage angle. When the drainage angle gets completely blocked, eyepressure rises very quickly. This is called an acute attack. During an acute attack a person may have some or all of the following symptoms Your vision is suddenly blurry;
severe eye pain
seeing rainbow-coloured rings or halos around lights
Many people with angle-closure glaucoma develop it slowly. This is called chronic angle-closure glaucoma. There are no symptoms at first, so they don't know they have it until the damage is severe or they have an attack.
Angle-closure glaucoma can cause blindness if not treated right away.
Major Risk Factors for Glaucoma
The main risk factors for glaucoma are:
an elevated eye pressure
All people over the age of 40 with a family history should see an optometrist or an ophthalmologist to be tested for glaucoma.
The only sure way to diagnose glaucoma is with a complete eye exam by an experienced optometrist or ophthalmologist.
A glaucoma screening that only checks the eye pressure is not enough to find glaucoma, because some people have glaucoma despite a normal pressure.
Examination of the optic nerve and drainage angle is critical to diagnose glaucoma.
Other tests such as special imaging of the optic nerve and visual field examinations are also important.
All forms of glaucoma are managed by lowering the eye pressure, even if the eye pressure is in the normal range. Lowering the eye pressure has been proven to reduce the progression of glaucoma.
Glaucoma is never cured, but in the vast majority of people, if carefully managed, it will not significantly impair vision. To achieve this requires ongoing follow-up with an ophthalmologist.
If diagnosed late or not treated effectively, then people do go blind from glaucoma. The vision loss from glaucoma is not reversible. In fact, glaucoma remains the world's leading cause of irreversible blindness.
There are 3 methods to lower the eye pressure:
Treatment with drops has been the traditional first-line therapy, but there is recent evidence that modern laser therapy called Selective Laser Trabeculoplasty (SLT) is preferable to drops.
SLT is a very safe procedure that only takes several minutes and is performed in the ophthalmologist's rooms. It may require 2 treatments and lasts several years. Retreatment is possible, and the majority of individuals will not require drops.
Surgery is generally reserved for situations when drops and/or laser are insufficient to control the glaucoma, but in some situations, especially when the glaucoma is severe, it may be the optimal option.
The traditional type of glaucoma surgery is called a trabeculectomy. It is a day-surgery procedure designed to increase the outflow of fluid from the eye and lower the eye pressure. It generally is very effective and often eliminates the need for drops. Over the past decade a number of newer glaucoma procedures have been developed using modern technology and biomaterials. These newer procedures may be performed in conjunction with modern cataract surgery. These newer techniques may not lower the pressure as much as traditional surgery. An experienced ophthalmologist can decide what the optimal type of surgery is for each individual.