Glaucoma: The Silent Thief of Sight

Glaucoma is one of the leading causes of blindness worldwide. It is estimated that over 4 million Americans have glaucoma but only half of those know they have it. In Malaysia, some form of glaucoma affect about 1 in 2,000 people. It leads to blindness by damaging the optic nerve. Elevated pressure in the eye is a risk factor, but even people with normal pressure can lose vision to glaucoma. Often there are no symptoms at first. Therefore a comprehensive eye exam can detect it.

What is glaucoma actually?

Well it is a group of diseases that can damage the eye’s optic nerve and result in vision loss and blindness. Most, but not all of these diseases are characterised by abnormally high level of pressure created by the fluid (aqueous) in the eyes. When this pressure (called intraocular pressure, IOP) remains high and fluctuates over a period of time, damage occurs to the delicate optic nerves. Currently, damage from glaucoma cannot be reversed. If left untreated, blindness often result.

The optic nerve connects the retina to the brain and is the light-sensitive tissue at the back of the eye. A healthy optic nerve is necessary for good vision. In the front of the eye is a space called the anterior chamber. A clear fluid (aqueous) flows continuously in and out of the chamber and nourishes nearby tissues. When the fluid reaches the angle, it flows through a spongy meshwork, like a drain, and leaves the eye.

Sometimes, when the fluid reaches the angle, it passes too slowly through the meshwork drain. As the fluid builds up, the pressure inside the eye (IOP) rises to a level that may damage the optic nerve. When the optic nerve is damaged from increased pressure, open-angle glaucoma-and vision loss-may result. That’s why controlling pressure inside the eye is important.

Most people’s Intraocular Pressure (IOP) falls between 8 and 21 mmHg. However, some eyes can tolerate higher pressures than others. A person has glaucoma ONLY if the optic nerve is damaged. If you have increased eye pressure but no damage to the optic nerve, you do not have glaucoma. However, you are at risk.

In general, types of Glaucoma consists of

• Open-angle glaucoma
• Acute Angle Closure glaucoma
• Congenital glaucoma
• Secondary glaucoma

Of theses one of the important emergency situations arise from Acute Angle-Closure

Glaucoma

Another group of interest would be the Secondary Glaucomas. These can develop as complications of other medical conditions. They can sometimes be associated with eye surgery or advanced cataracts, eye injuries, certain eye tumours, or uveitis (eye inflammation). A severe form, called neovascular glaucoma, is linked to diabetes. Medications like steroid drugs used to treat eye inflammations and other diseases can trigger glaucoma in some people. For this type, both the glaucoma and the underlying problem must be treated.

Who is at risk?

• People over the age of 45
• People who have family history of glaucoma
• People with abnormally high Intraocular pressure (IOP)
• Diabetes
• Myopia (Short sightedness)
• Regular, long term steroid use
• A previous eye injury

Detection and diagnosis is important for various reasons. In early stages of open angle glaucoma, a person will not experience any symptoms. The early visual changes are very slight, usually only affect peripheral vision. The centre of the field is last affected so that eventually it becomes like looking through a long tube, so called ‘tunnel vision’. In time even this sight would be lost!

It is therefore, important to have your eyes checked regularly, because early detection and treatment of glaucoma are the only way to prevent vision impairment and blindness.

A number of tests may be performed, which will help to determine whether or not you have glaucoma or are especially likely to develop the disease:

• Normal optic disc as seen by the doctor.
• Size of your optic disc changes in relation to glaucoma.

This condition can be treated!

Treatment is varied but most commonly involves medications, usually prescription eyedrops, but surgery (filtering surgery or laser surgery) to lower the pressure in the eye and thereby controlling further damage to the optic nerve may sometimes be needed. While there is no cure as yet for glaucoma, early diagnosis and continuing treatment can preserve eyesight.

Living with Glaucoma

A diagnosis of glaucoma shouldn’t prevent you from enjoying your life. Remember, most cases of glaucoma are managed through medications, surgery, or a combination of both. With an early diagnosis, most people with glaucoma do not go blind. Your medication schedule will probably be the biggest change. Arranging your timetable and visits to your doctor will become a normal routine!