Glaucoma is a complicated disease in which damage to the optic nerve results in vision loss
Glaucoma is an eye disease, where the high fluid pressure within your eye damages the delicate fibres of the optic nerve. These delicate nerve fibres are responsible for carrying visual impulses from your eye to the brain. This damage can lead to blindness in advanced cases. Glaucoma accounts for 40% of blindness in Singapore.
There are several types of glaucoma. Some types of glaucoma has no early warning signs or painful symptoms. It develops slowly without notices as the patient suffer sight loss very gradually over many years. The two most common types of glaucoma are open-angle glaucoma and angle-closure glaucoma. These are marked by an increase of intraocular pressure (IOP), or pressure inside the eye.
Open-angle glaucoma, the most common form of glaucoma, accounting for at least 90% of all glaucoma cases:
Is caused by the slow clogging of the drainage canals, resulting in increased eye pressure
Has a wide and open angle between the iris and cornea
Develops slowly and is a lifelong condition
Has symptoms and damage that are not easily noticeable in early stage
“Open-angle” means that the angle where the iris meets the cornea is as wide and open as it should be. Open-angle glaucoma is also called primary or chronic glaucoma. Peripheral and night vision will be affected before your central reading vision.
Angle-closure glaucoma, a less common form of glaucoma:
Is caused by blocked drainage canals, resulting in a sudden rise in intraocular pressure
Has a closed or narrow angle between the iris and cornea
Develops very quickly
Has symptoms and damage that are usually very noticeable
Demands immediate medical attention.
Sudden rise in intraocular pressure results in eye pain and redness, headache and nausea. Other accompanying symptoms include blurred vision and seeing of coloured rings around lights. It is also called acute glaucoma or narrow-angle glaucoma. Unlike open-angle glaucoma, angle-closure glaucoma is a result of the angle between the iris and cornea closing.
Normal-Tension Glaucoma (NTG)
Also called low-tension or normal-pressure glaucoma. In normal-tension glaucoma the optic nerve is damaged even though the eye pressure is not very high. We still don't know why some people’s optic nerves are damaged even though they have almost normal pressure levels.
Causes of Secondary Glaucoma
Secondary glaucoma is usually the result of a pre-existing eye condition such as inflammation, severe diabetic eye disease and tumors. Previous eye injury or surgery as well as long term steroid use may also cause secondary glaucoma.