Glaucoma

Glaucoma is a disease of the optic nerve. Optic nerve is the part of the eye that carries images we see from the eye to the brain. The optic nerve is made up of many nerve fibres (like an electric cable containing numerous wires). Glaucoma damages nerve fibres, which can cause blind spots in our vision and vision loss will develop.

WHAT ARE THE CAUSES?

There are many causes of optic nerve head failure, just like there are many causes of heart failure. The unique feature of this condition is there are absolutely no symptoms in majority of the cases in early stages. By the time vision is affected, it is too late to reverse the blindness caused by it. This is how the disease is known as the sneak thief of sight! You just do not realize you have this condition until it is too late.

RISK FACTORS

One major risk factor has to do with the pressure inside the eye or intraocular pressure (IOP). When the clear liquid called the aqueous humor which normally flows in and out of the eye cannot drain properly, pressure builds up in the eye. The resulting increase in IOP can damage the optic nerve.
Other risk factors are: being in the older age-group

  • Family History
  • Extreme Refractive Errors (Long-Sightedness/ Short-Sightedness)
  • Diabetes
  • Migraine
  • History of Steroid Use
  • Eye injury

This list is not exhaustive. If you are above 40 and have the risk factors mentioned above, you are:

PRIMARY OPEN-ANGLE GLAUCOMA

The most common form of glaucoma is primary open-angle glaucoma, where the aqueous fluid that normally circulates in the front portion of the eye is blocked from flowing out of the eye through a tiny drainage system. This causes the pressure inside your eye to increase, which can damage the optic nerve and lead to vision loss. Most people who develop primary open-angle glaucoma do not notice any symptoms until their vision is impaired.

ANGLE-CLOSURE GLAUCOMA

In angle-closure glaucoma, the iris (coloured part of the eye) may drop over and completely close off the drainage angle, abruptly blocking the flow of aqueous fluid. This can lead to increased IOP or optic nerve damage. In acute angle-closure glaucoma, there is a sudden increase in IOP due to the build-up of aqueous fluid. This condition is considered an emergency because optic nerve damage and vision loss can occur within hours of the problem. Symptoms can include headache, nausea, vomiting, seeing haloes or colours around lights, and eye pain. If you fit any of the criteria – female or in the older age-group or have hyperopia (longsightedness), you are at higher risk of this type of glaucoma.

NORMAL TENSION GLAUCOMA

Even people with “normal” IOP can experience vision loss from glaucoma. This condition is called normal tension glaucoma. With this type of glaucoma, the optic nerve is damaged even though the IOP is considered normal. Normal tension glaucoma is not well understood but we do know lowering the IOP has been shown to slow down progression of this form of glaucoma.

PAEDIATRIC OR CHILDHOOD GLAUCOMA

Childhood glaucoma is rare and can start in infancy, childhood or adolescence. Like primary open-angle glaucoma, there are few, if any, symptoms in the early stage. Blindness can result if left untreated. Like most types of glaucoma, this type of glaucoma may be hereditary.

TREATMENT & SURGERY

Regular examinations with your ophthalmologist are important if you are at risk for this condition. If you are diagnosed to have glaucoma, the normal treatment is to use eye drops to lower your intraocular pressure. There are many types of effective eye drops available nowadays and are usually administered once or twice daily. However if you are diagnosed to have angle closure then the definitive treatment is to perform a laser to open up the angles.
Treatment and follow-up checks for glaucoma require life-long effort. It is similar to having high blood pressure or diabetes. If you control your blood pressure or diabetes, then you are unlikely to get complications. If you are a glaucoma patient who control your intraocular pressure, then blindness can be prevented. If you stop using eye drops or stop going for follow-up eye checks, then the disease can still progress and lead to blindness.
Surgery can be done if your eye pressure cannot be controlled despite being treated with eye drops or laser. If your disease has not worsened, surgery can prevent further visual field loss. Surgery, however, cannot recover any lost vision. There are a number of operations that can be done to lower the intraocular pressure and your eye specialist will be able to advise you on the most suitable treatment.