Glaucoma - Symptoms, Treatment, Causes & Types

What Causes Glaucoma?

Since the optic nerve carries impulses from the eye to your brain, damage to it will result in visual impairment. Common causes for optic nerve damage, & hence glaucoma, include:

• Accumulation of aqueous humor (fluid found in your eye), raising the pressure in the eye
• Hypertension
• Loss of blood supply to the nerve
• Trauma
• Genetic abnormalities

Types of Glaucoma

Glaucoma can be divided into two main categories:

• Open-Angle Glaucoma
• Closed-Angle Glaucoma

Open-Angle Glaucoma 

Glaucoma with the presence of a wide-angle between the iris & cornea is called ‘open-angle glaucoma’. The trabecular meshwork which is responsible for the drainage of fluid is blocked, resulting in elevated pressure due to fluid accumulation. This presses on the optic nerve, damaging it.

Open-angle glaucoma is the most common type of glaucoma, & usually shows a gradual progression. So it may go unnoticed for a long time.

Closed-Angle Glaucoma

The iris may bulge forward to reduce the angle formed with the cornea. The reduced space hinders fluid circulation & drainage. Increased pressure on the optic nerve then causes closed-angle glaucoma.

Depending on how fast the condition progresses, you could suffer from acute or chronic closed-angle glaucoma. Acute closed-angle glaucoma requires immediate intervention.

Other Types of Glaucoma

• Normal Pressure Glaucoma: There is no identified cause. Glaucoma in this case may be due to inadequate blood supply, as in atherosclerosis within the vessels supplying the nerve. As a result, the optic nerve degenerates. The intraocular pressure remains within normal range in this condition.

• Pigmentary Glaucoma: Pigments found at the back of the iris break off & block the drainage system resulting in an increase in pressure within the eye.

• Pseudoexfoliative Glaucoma: Material breaks off the lens to collect within the angle between the iris & cornea to disrupt drainage of fluid.

• Traumatic Glaucoma: Damage to the optic nerve occurs as a result of bruises or penetrative injury to the eye. Symptoms may occur immediately or after years.

• Congenital Glaucoma: Malformation or blockage of the trabecular system present at birth can cause glaucoma. It may occur due to genetic defects or defective development during pregnancy. Glaucoma may occur with other defects within the eye.

• Neovascular Glaucoma: Formation of new blood vessels that cover the drainage system, resulting in fluid accumulation, is usually associated with other conditions, most often diabetes.

• Irido-Corneal Endothelial Glaucoma (ICE): This is a rare form of glaucoma that usually affects one eye.  The abnormal layer of cells covers the posterior surface of cornea & also sweeps over the angle to cover it, to disrupt drainage, & may even cause the iris & cornea to partially fuse, increasing the pressure even more.

Risk Factors for Glaucoma

The risk of developing glaucoma can increase due to the following factors:

• Age (especially those above 60)
• Family history of glaucoma
• High intraocular pressure
• Other conditions such as diabetes, heart disease or hypertension
• Regular use of corticosteroid containing eye drops
• History of eye surgery or trauma
• Abnormally thin cornea
• Extreme far-sightedness or short-sightedness