Glaucoma is called the silent thief of sight. Did you know that it causes irreversible blindness? Why is it called ‘silent thief’? With open angle glaucoma, the most common form, there are virtually no symptoms until the late stage, or end stage of the disease, when often it is too late to preserve vision.
Vision loss starts with peripheral or side vision. You may compensate for this unconsciously by turning your head to the side and most people will not notice anything until significant vision is lost.
What Is Glaucoma?
Glaucoma is a disease of the optic nerve which is similar to the ‘film’ in a camera. The optic nerve carries the images we see from the eye to the brain, where the image is processed. Glaucoma causes irreversible damage to the nerve (film of the camera) which causes blind spots in our vision and eventually blindness.
When the fluid within the eye is unable to drain out of the eye as normal (due to many reasons), the pressure of the fluid builds up in the eye and the resulting increase in pressure damages the optic nerve.
Are You At Risk For Glaucoma? YES if
- You have a family history of glaucoma – (Siblings of patient have 4 times the risk; child of patient, double the risk)
- Advanced age – More than 60 years of age (You are 6 times more likely to get glaucoma)
- Asians – Mongol / Chinese descent (Higher risk for angle closure glaucoma)
- Previous eye injury
- Steroid users (whether in the form of tablet or eyedrop)
- Other risk factors – Short sightedness / hypertension
What Is Glaucoma?
Open angle glaucoma is the most common type of glaucoma, which makes up 90% of all glaucoma cases. This condition is caused by the slow clogging of the drainage canals of the eye, causing fluid to accumulate and the eye pressure to increase.
Angle closure glaucoma is a less common form of glaucoma, where the iris (the coloured part of the eye) drops over and completely blocks off the drainage angle. There is a sudden tremendous increase in eye pressure. This is an emergency, as optic nerve damage and vision loss can occur within a few hours. These patients are the only ones with glaucoma who have symptoms early on, which include severe eye pain, headache, vomiting and seeing halos around lights.
Although normal eye pressure is considered less than 21mm (mercury), this can be misleading. Some patients have a type of glaucoma called Normal tension glaucoma. In this type of glaucoma, the optic nerve is damaged even though the pressure in the eye is normal.
Glaucoma tests include:
- Measuring the pressure in your eye
- Inspecting your eye’s drainage angle
- Examining your optic nerve
- Visual field testing which tests for blind spots in your vision
The examination can take up to one hour as the doctor needs to dilate the pupil to examine the optic nerve in detail. Dilatation of the pupil is done by inserting eye drops and the effect of the drug can last up to 8 hours. After dilatation, vision will be blurred, hence it is important for an accompanying person to drive home.
Visual field testing is only done if glaucoma is suspected and usually on another day.
Early Detection And Treatment Can Prevent Blindness
All patients over the age of 40 should have an eye examination every 2 years. This is a compulsory part of the general examination in some countries to prevent blindness from glaucoma. As explained earlier, there are no symptoms of the condition until the advanced stage when it is often too late. Late symptoms include blindness, frequently knocking into objects, inability to see objects in the periphery without turning your head.
Treatment Of Glaucoma
Medicated eye drops are the most common way to treat glaucoma. These medications lower your eye pressure in one of two ways, either by slowing down the production of fluid in your eye or by improving the drainage of fluid out of the eye.
For some patients however, laser surgery or intraocular surgery is required.
As I tell all my patients, your eyes are your best friends, especially as you get older. To preserve vision, it is recommended that you have your eyes screened for glaucoma from the age of 40 or earlier if you have the risk factors. Remember early detection can prevent blindness.