Primary open-angle glaucoma: causes, symptoms, treatment


Glaucoma is the second leading cause of blindness worldwide, affecting approximately 70 million people in the world. Primary open-angle glaucoma is the most common type of glaucoma.

In the United States, about 80 percent of people with glaucoma have primary open-angle glaucoma.

Primary open-angle glaucoma is a progressive disease, which means that if left untreated, it gets worse over time. The good news is that it can be detected with regular eye and sight screenings. Treatment cannot restore your sight, but it can slow the progression of the disease and prevent further vision loss.

This article will look at the causes, symptoms, and treatment of primary open-angle glaucoma and whether there are steps you can take to prevent it.

Primary open-angle glaucoma is an eye condition that causes progressive blindness. To understand how the disease affects your eyes and sight, it is important to look at two key functions that occur in a healthy eye.

Researchers haven’t yet identified exactly what causes your eyes to stop clearing properly. In some cases, the nerves that activate and deactivate the drainage process are not functioning well.

In other cases, tiny particles of pigment, blood cells, proteins, and other debris can block drainage from the trabecular meshwork. Steroid therapy can also increase the pressure inside your eyes.

A Research report 2020 have shown that primary open-angle glaucoma occurs more frequently in:

  • adults over 40
  • Black people
  • people with a family history of glaucoma

Certain health conditions can increase the risk of developing primary open-angle glaucoma. These include:

Using birth control pills, alcohol, and tobacco products can also increase your risk of developing primary open-angle glaucoma.

Closed-angle glaucoma means that the iris (the colored ring) of your eye meets the cornea at an angle that blocks both the trabecular meshwork and the uveoscleral drainage systems.

Closed-angle glaucoma usually causes severe pain, nausea, and blurred vision. It often comes on suddenly and is a medical emergency.

When the trabecular meshwork is blocked but the uveoscleral drain is open, glaucoma is said to be open-angle.

When glaucoma occurs without any underlying health problem (such as cataracts or injury to the eye), the disease is said to be primary.

Primary open-angle glaucoma means the disease has developed without a known cause. Most cases of glaucoma are primary open-angle glaucomas.

When another health problem causes or contributes to the development of glaucoma, the disease is called secondary glaucoma. In other words, glaucoma developed as a result of changes caused by the other health problem.

In the early stages, primary open-angle glaucoma usually has no noticeable symptoms.

In advanced stages, it can cause blurred vision in one or both eyes, as well as a narrowed field of vision.

With primary open-angle glaucoma, vision loss begins at the outer edges of your field of vision. As the disease progresses, your field of vision narrows. If left untreated, primary open-angle glaucoma can lead to blindness.

An ophthalmologist or optometrist may test your eyes for glaucoma as part of a routine eye exam. There are several types of tests your eye doctor can use to check for signs of glaucoma.

  • Tonometry. This test measures the pressure inside your eye. After you numb your eyes with eye drops, your doctor will use a small device called a tonometer to measure the internal pressure in your eyes.
  • Ophthalmoscopy. Your doctor or a technician will give you eye drops to dilate your pupil – it’s the opening in the front of your eye that lets light in. Once your eye is dilated, your eye doctor will use a device with a light on the end to examine your optic nerve.
  • Visual field test. This test involves covering one eye at a time, then looking straight ahead as lights flash in your peripheral vision. The purpose of this test is to determine if you have any loss of your peripheral vision.
  • Pachymetry. With this quick and painless test, your doctor will gently place a probe in the front of your eye to measure the thickness of your cornea. This test is done because the thickness of the cornea can, in some cases, influence eye pressure readings.
  • Gonioscopy. After numbing your eye with drops, your doctor will place a hand-held contact lens over your eye to determine whether the angle where the iris meets the cornea is open or closed.

The goal of primary treatment for open-angle glaucoma is to reduce the pressure in your eye to prevent further damage or loss of vision. Treatments vary depending on how advanced your glaucoma is and the possible cause of the problem.


The National Eye Institute says the first-line treatment for primary open-angle glaucoma is usually prescription eye drops. Prostaglandins are one of the most common types of eye drops to help treat this condition.

Prostaglandins are fatty acids that can help improve drainage inside your eye. These drops are taken before bedtime every night. Some of the most commonly prescribed prostaglandins for primary open-angle glaucoma include:

Some other types of eye drops can help reduce the amount of fluid your eyes make. These drugs include:

  • beta-blockers
  • alpha-adrenergic agonists
  • carbonic anhydrase inhibitors

Glaucoma eye drops are generally safe for most people. However, there is a small possibility of side effects such as:

  • change the color of your iris
  • stinging and redness in the eye
  • blurred vision
  • dry mouth

Laser treatment

If the eye drops do not lower eye pressure enough, your eye doctor may recommend a type of laser procedure called selective laser trabeculoplasty (SLT). Some new search has shown that SLT can be as effective as eye drops in early glaucoma.

This in-office procedure only takes a few minutes and involves your eye doctor directing a laser at the drainage tissue in your eye.

Laser energy causes a chemical change in the eye tissue that can cause the fluid to drain inside your eye better. This, in turn, can help reduce the pressure inside your eye by 20 to 30 percent, according to the Glaucoma Research Foundation. This procedure is successful in about 80% of cases and the effects usually last between 3 and 5 years.

Your eye will be numb during the laser treatment, but there may be some tenderness, redness, or dryness afterwards. Your doctor may prescribe eye drops to help your eye heal.


Several types of surgery can be performed to promote better drainage. This includes:

  • minimally invasive glaucoma surgery, which involves a surgeon using microscopic tubes to drain fluid from the eye
  • trabeculectomy, in which the surgeon opens a small hole in the surface of your eye to allow fluid to escape
  • glaucoma implant surgery, where surgeons place a small tube called a shunt in your eye to help drain the fluid properly

Some people of certain ages, races, or family history develop primary open-angle glaucoma more frequently, which can lead to eye changes that cause glaucoma. If you’re worried about developing this condition, your doctor can work with you to help you manage your overall eye health as much as possible.

If you have a condition that increases your risk of developing primary open-angle glaucoma, it is important to manage the condition well. And if you smoke, drink alcohol, or take birth control pills, you may want to talk to a healthcare professional about ways to reduce your risk of glaucoma.

The most important preventative measure you can take is to have regular eye exams. Since symptoms do not appear until later in this disease, it is important to catch glaucoma early to prevent vision loss.

Primary open-angle glaucoma is a progressive disease that can lead to permanent vision loss or even blindness if left untreated. This happens when the ganglion cells in the retina are damaged, causing the progressive loss of peripheral and then central vision.

Primary open-angle glaucoma is caused by too much pressure in the eye. When fluid does not flow properly, excess pressure can damage the optic nerve.

Primary open-angle glaucoma does not cause vision loss or other symptoms until later stages. For this reason, it is important to have regular eye exams. Your eye doctor can test the pressure in your eye and assess your field of vision for glaucoma at an early stage, before it affects your vision.


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