Glaucoma is the name given to a group of eye diseases in which damage occurs to the optic nerve at the back of the eye causing decreased peripheral (side) vision and, eventually, blindness. In most people, this damage is due to increased pressure inside the eye as a result of blockage of the circulation or drainage of aqueous (the clear fluid that carries oxygen, sugars, and other essential nutrients to the structures of the eye and helps to maintain the shape of the eye). In other patients the damage may be caused by poor blood supply to the vital optic nerve fibres, a weakness in the structure of the nerve, or a problem in the health of the nerve fibres.
Glaucoma is a significant cause of blindness in Asia. In fact glaucoma is one of the leading causes of blindness and impaired vision among people in all parts of the world. Different populations tend to suffer from different types of glaucoma. In general, Africans and Asians are more inclined to develop glaucoma and to lose their sight than Caucasians.
WHAT CAUSES GLAUCOMA?
Increased intraocular pressure is one cause of damage to the optic nerve, and indicates a problem with too much aqueous fluid in the eye. This may be due to the eye producing too much aqueous, the aqueous not draining properly through the outflow facility (the trabecular meshwork), or the angle formed between the cornea and the iris is narrow or closed, blocking the drainage of aqueous.
Some people have glaucoma, but still have normal intraocular pressure. The cause of this type of glaucoma is thought to be related to poor blood flow to the optic nerve.
While glaucoma is more common as people age, it can occur at any age. Glaucoma tends to run in families so family history is a risk factor. Other risk factors include race, diabetes, migraines, short sightedness (myopia), eye injuries, blood pressure, or use of cortisone drugs (steroids).
HOW IS GLAUCOMA DETECTED?
Regular eye examinations are the best way to detect glaucoma early. A glaucoma test usually includes the following tests:
CAN GLAUCOMA BE TREATED?
- optic nerve check with an ophthalmoscope
- eye pressure check (tonometry)
- visual field assessment if needed – this tests the side vision, which is first affected by glaucoma
Although there is no cure for glaucoma it can usually be controlled and further loss of sight prevented. Treatments include:
- Eyedrops – these are the most common form of treatment and must be used regularly. Some patients may respond quickly to a drug while others may not respond as well, but the drops can be varied to best suit the patient and the type of glaucoma.
- Laser (laser trabeculoplasty) – this is performed when eye drops do not stop deterioration in the field of vision. In many cases eye drops will need to be continued after laser. Laser does not require a hospital stay.
- Surgery (trabeculectomy) – this is usually performed if eye drops and laser treatment have failed to control the eye pressure. A new channel to enable the fluid to leave the eye is created. Treatment can save the remaining vision but it does not improve eye sight.
TYPES OF GLAUCOMA
The two most common types of glaucoma are primary open angle glaucoma (POAG) and acute or chronic closed angle glaucoma. Other types of glaucoma include normal tension glaucoma, congenital glaucoma, pigmentary glaucoma, and secondary glaucoma.