Did you know that there are many types of glaucoma? This fact may be surprising to many because when people think of glaucoma, they typically think of a condition that causes high pressure in the eye. However, there is more than one type of glaucoma. Each is different. All of them pose the risk of sight loss. This article reviews several types of glaucoma and their causes.

What is Glaucoma?

Glaucoma is an eye disease that is one of the leading causes of blindness. All types of glaucoma have the potential to damage the optic nerve. The optic nerve connects the eye to the brain, sending information that lets us see. Damage to the optic nerve causes sight loss that may lead to total blindness. When an optic nerve is damaged, it cannot be healed or fixed. Prevention of damage is critical for people with glaucoma.

Types of Glaucoma:

There are many different types of glaucoma. All types of glaucoma can result in partial or full loss of vision if not found and treated early.

Primary Open-Angle Glaucoma

Primary Open-Angle Glaucoma (POAG) is one the most common types of glaucoma. Our eyes are “inflated” with fluid to keep their shape and function, just like the tire on your car is filled with air. And just like a car tire, there is an ideal range of pressure needed by the eye for proper vision. With POAG, too much fluid in the eye creates pressure on the optic nerve. This process is usually painless and may occur slowly over the years. As the eye pressure continues to increase, the optic nerve loses blood flow resulting in damage and potential blindness.

Normal Tension Glaucoma

Normal Tension Glaucoma (NTG) does not cause an abnormal increase in eye pressure — instead, blood flow problems to the optic nerve cause the eye to become sensitive and harmed by normal levels of pressure. Since the veins that feed the optic nerve are very fragile, diseases that cause damage to veins and circulatory problems, such as diabetes and heart disease, play a role in this process. Both POAG and NTG cause painless damage to the optic nerve and loss of sight.

Acute Angle Closure Glaucoma

Acute Angle Closure Glaucoma (AACG) happens when the part of the eye that drains the fluid becomes blocked. The fluid buildup causes the eye to swell quickly. As a result, the sharp increase in pressure may cause pain in the eye. Other warning signs include blurry vision, headache, nausea, vomiting or seeing rainbow-colored circles around lights. Anyone experiencing these symptoms needs immediate emergency medical care. AACG can cause blindness within 24 hours.

Secondary Glaucoma

Secondary Glaucoma (SG) happens as the result of an eye or head injury, another eye condition, or a tumor. Problems from diabetes, cataracts, and eye surgery also cause this type of glaucoma. The optic nerve damage can occur from the injury, pressure or swelling caused by these conditions, leading to sight loss.

Unfortunately, most types of glaucoma have no early warning signs. Therefore, it is critical to get regular eye exams to detect glaucoma. Sight loss is avoidable with early detection and treatment.

Glaucoma can happen to anyone, but some people are more likely to get it. Those with family members who have glaucoma, have health conditions like diabetes or heart disease, or are African American, Hispanic, Asian or Native American are all at higher risk. If you have not had an eye exam in the last two years, you should schedule one today.


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