What is glaucoma?
Glaucoma is an eye condition where most commonly, there is build up of pressure in the eye, resulting in damage to the optic nerve. The optic nerve is the cable of the eye that carries images from the eye to the brain. This results in vision loss.
Pressure in the eye is needed to help it keep its shape. Normal eye pressure is maintained when fluid produced by the eye exits via a drainage system of the eye. When this drainage channel clogs up and fluid begins to build up, high eye pressure occurs. The high pressure within the eyeball pushes on the optic nerve, damaging it slowly and irreversibly.
Glaucoma is one of the world’s leading causes of blindness. Blindness can be prevented if it is diagnosed and treated early. As there are few warning symptoms, regular eye tests can help detect the onset of the disease.
Two main types of glaucoma
Primary open angle glaucoma (POAG)
This is the most common form of glaucoma. It usually affects both eyes and develops slowly such that loss of sight is gradual. It is often called the “Silent thief of Sight”.
Primary angle closure glaucoma (PACG)
Acute angle closure occurs more commonly in middle-aged or elderly Chinese females, especially those who are long-sighted. Patients may experience a sudden increase in eyeball pressure due to a blockage preventing fluid from flowing out of the eye. There is a high risk of damage to the optic nerve and urgent treatment is needed to lower the eye pressure.
Patients with PACG will experience a sudden onset of pain, redness and blurred vision in one or both eyes. The pain can be very severe and is often accompanied by headache, nausea and vomiting.
Chronic angle closure
It is usually caused by a gradual rise in pressure in the eye due to a blockage preventing fluid from flowing out of the eye. Its slow and silent development over a prolonged period means there are no noticeable symptoms until the advanced stage before visual loss is noted.
Sometimes, other diseases of the eye can cause a rise in the pressure within the eye such as an advance cataract or severe diabetic eye disease. There is also a congenital form of the disease present from birth known as congenital glaucoma.
Am I at risk of glaucoma?
You have a greater risk of glaucoma if:
- A member of your family, particularly siblings has been diagnosed with glaucoma.
- You have severe myopia (short-sightedness).
- It is also a natural ageing change that occurs in many people simply as a result of growing older.
How is glaucoma detected?
To determine if you have glaucoma you will be required to undergo a series of pain-free tests that look at both the structure and function of the eye nerve. Some of these will involve eyedrops that may temporarily blur your vision. You should therefore avoid driving on the day of your appointment.
Some of these test are:
The ophthalmologist holds a special contact lens against the eye. This allows them to see the area where the fluid in the eye normally drains and check for blockage or narrowing.
Visual field test
This measures the range of your “all around” vision to check for any visual loss. The test takes about 15 minutes per eye. You will be asked to sit at a screen and fix your gaze on a central light target. A series of other lights are then shone and you will need to press a button indicating if you can see them. This will detect any missing areas in the visual field caused by damage to the optic nerve.
- Optic nerve assessment
You may have photographs taken or computerised imaging to look for any damage to the eye nerve.
How will glaucoma affect me?
Glaucoma can be treated but not cured. Treatment can control the disease and prevent further loss of vision. It is important to go for regular check-ups to manage the condition. Any vision loss you might already have will also be permanent. It is important that treatment be maintained throughout your life as not doing so may result in further loss of sight.
These are often prescribed in the early stages of glaucoma to lower the eye pressure.
Lasers can be used for angle closure glaucoma to widen the angle and create an opening that allows the fluid to flow from the front to the back part of the chamber of the eye, which has the collecting drainage. Complications are rare and include slight inflammation, mild spikes of eye pressure or possible damage to the inner layer of the cornea.
For more severe cases of glaucoma, surgery may be necessary. A common operation is a trabeculectomy, where a small piece of tissue is removed to allow for a new opening to drain fluid from the eye. Another surgery involves tube insertion under the conjunctiva (white of the eye) to increase fluid outflow. Post-operative wound care is very important because it will determine the success of fluid flow. Eye drops that contain anti-inflammatory agents are to be used properly to prevent early wound healing that can cause drainage failure. Anti-infective eyedrops should be used for a shorter time to prevent infection.