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5 Things You Need To Know About Normal-Tension Glaucoma

Glaucoma is a well-known eye disease that damages your optic nerve, often due to increased pressure inside the eye, and eventually leads to blindness. This is common knowledge, but it's less commonly known that there are many different types of glaucoma. Even more surprisingly, one type of glaucoma causes damage without the increased eye pressure that is a key marker of the other types. Here's what you need to know about normal-tension glaucoma. 

What causes normal-tension glaucoma?

Researchers still aren't sure what causes normal-tension glaucoma; it's one of the biggest mysteries in the field of optometry. Things like low blood pressure, occasionally elevated pressure inside the eye, and problems with the body's circulatory system have been proposed as possible causes. Peripheral vascular dysfunction, which causes cold hands and feet, is thought to affect the blood flow to the eyes as well, which leads to damage. More research is needed to figure out the exact cause of this condition. 

What are the signs of normal-tension glaucoma?

Normal-tension glaucoma is a type of open-angle glaucoma. It develops very slowly, so you may not realize that anything is wrong. Peripheral vision is the first part of your vision that is affected by glaucoma and this may not be noticeable. Peripheral vision helps you see things in your outer field of vision, also called the corner of your eye. As the glaucoma gets worse, your central vision will start to become affected, but since it happens slowly, you may just think it's a normal part of aging. If nothing is done, all of your vision will eventually be lost. 

Can your optometrist test you for this type of glaucoma?

Your optometrist can perform optical coherence tomography to examine your eyes for signs of this type of glaucoma. For this test, your pupils will be dilated with eye drops to make the insides of your eyes more visible.. Next, you will sit in front of a special machine that takes photos of the inside of your eye; it will take about 15 minutes for the machine to take these photos. Your optometrist will examine these photos for signs of damage to the optic nerve. Damage to the optic nerve can be a sign that you have glaucoma. 

Can it be treated?

Normal-tension glaucoma is treated just like other types of glaucoma, by reducing the pressure inside the eye. Even though people with this condition don't have high eye pressure, researchers have found that reducing their normal eye pressure by 30% stops the progression of the disease in about half of patients. Your optometrist may want to start treatments to lower your eye pressure, even if your eye pressure is within the normal range. 

This pressure can be reduced with medications like beta-blockers or calcium channel blockers. These medications are the same ones that are used to treat people with high blood pressure, so if you have low blood pressure, you may not be able to take them. If you can't take the medications, or if the medications aren't enough, you may need to have surgery. The goal of surgery is to help fluids drain from the inside of your eye, which reduces the pressure.  

Is normal-tension glaucoma rare?

Normal-tension glaucoma doesn't get as much attention as the other types, but it's not a rare problem. Between 20% and 40% of Americans with glaucoma have normal-tension glaucoma, according to studies.

Normal-tension glaucoma isn't as well-known as other types of glaucoma, but it's very common. The symptoms of this condition are easy to miss since a gradual decrease of vision can seem like a normal part of getting older, so make sure you're seeing your optometrist regularly for eye exams.