What Are the Types of Glaucoma?

Open Angle Glaucoma

Open Angle Glaucoma often also called primary or chronic open angle glaucoma is the most common type. The damage to the optic nerve progresses slowly and destroys peripheral vision gradually.

The mechanism for this type of glaucoma occurs when the drainage angle appears to be open but does not function properly leading to increased pressure in the affected eyes.

Typically there are no symptoms in the early stages of this type of glaucoma.

Angle Closure Glaucoma

This type of glaucoma is also known as acute glaucoma or narrow angle glaucoma. It is rarer and is very different to open-angle glaucoma in that the eye pressure usually rises very quickly.

This happens when the drainage canals get blocked. The outer edge of the iris bunches up over the drainage canals, when the pupil enlarges too much or too quickly. This can happen when entering a dark room. A simple test can be used to see if your angle is normal and wide or abnormal and narrow.

Symptoms of acute angle-closure glaucoma may include headaches, eye pain, nausea, halos around lights at night, and very blurred vision.

Low Tension Glaucoma

Normal-tension glaucoma (also called low-pressure glaucoma) is a unique condition in which optic nerve damage and vision loss have occurred, despite a normal pressure inside the eye.

Eye pressure, called intraocular pressure (IOP), is measured in millimetres of mercury (mm Hg). Normal eye pressure ranges from 10-21 mm Hg. Most people with glaucoma have an IOP of greater than 21 mmHg. However, in normal-tension glaucoma, people have pressures within the normal range.

Although its cause is not completely understood, normal-tension glaucoma is generally believed to occur either because of an unusually fragile optic nerve that can be damaged despite a normal pressure inside the eye or because of reduced blood flow to the optic nerve.

Congenital Glaucoma

This is a rare form of glaucoma. Childhood glaucoma — also referred to as congenital glaucoma, paediatric, or infantile glaucoma — occurs in babies and young children. It is usually diagnosed within the first year of life. It may be an inherited condition, caused by incorrect development of the eye's drainage system before birth. Parents may note that the child is sensitive to light, has enlarged cloudy eyes and excessive watering. Surgery is usually indicated.

Secondary Glaucoma

This type of glaucoma usually develops as a result of other disorders of the eye such as an injury, cataracts and eye inflammation. The use of cortisone steroids has a tendency to raise eye pressure and therefore IOP should be checked frequently whilst using these types of medications.