Symptoms, Causes, Treatment & More

Open-angle glaucoma is an eye disease that causes a gradual loss of vision. It is the most common type of glaucoma, a set of eye diseases that affect the eye’s optic nerve. The optic nerve is located at the back of the eye and sends visual messages to the brain. In open-angle glaucoma, fluid pressure in the eye slowly rises and damages the optic nerve.

The exact cause of open-angle glaucoma is unknown, but certain conditions like diabetes and high blood pressure (hypertension) increase your chances of developing it. An estimated 2.7 million people in the United States have glaucoma, with open-angle glaucoma accounting for about 90% of those cases.

Open-angle glaucoma often doesn’t cause symptoms in its early stages. The first sign is usually the start of vision loss. This vision loss is irreversible and can worsen over time.

Although there is no cure, treatments can stop or slow the progression of open-angle glaucoma. There also are ways to manage symptoms and accommodate to life with this condition.

Typically, early stages of open-angle glaucoma don’t cause symptoms. The symptoms only begin when the disease is already advanced. It can take years to decades before vision is affected.

When vision loss does start, it usually affects both eyes. The vision loss then gets worse over time. The signs of open-angle glaucoma include:

• Tunnel vision: The first sign of open-angle glaucoma is a gradual loss of peripheral (side) vision. This means that while you’re still able to see in front of you, the side view of your vision decreases. This decreased field of vision on your sides is informally known as tunnel vision.
• Blind spots: As open-angle glaucoma advances, blind spots (scotoma) develop in the peripheral vision. These blind spots can advance to complete vision loss.
• Loss of acuity: People lose visual acuity—the ability to see details near or far away—and may have blurry vision. This is a loss of central vision, or what you see in front of you.
• Vision loss: In the most advanced stages and if untreated, open-angle glaucoma can significantly impair vision, leading to a loss of light perception. However, total loss of vision is rare. 

Open-angle glaucoma occurs as retinal ganglion cells in the back of the eye degrade and die. These cells, which form the retina nerve layer, capture visual information and transmit it through the optic nerve to the brain. Symptoms of open-angle glaucoma arise as the retina nerve layer progressively thins.

Researchers aren’t certain what causes open-angle glaucoma, but they think most cases result from rising pressure inside the eye, or an increase in intraocular pressure (IOP).

The inside of the eye is filled with fluid known as aqueous humor. The eye constantly makes and releases this fluid.

In a healthy eye, excess aqueous humor exits through the trabecular meshwork, which are canals located between your iris (the colored part of the eye) and cornea (the clear outer portion). If this fluid can’t escape or the eye makes too much fluid, pressure builds up. That pressure pushes on your optic nerve, damaging it.

Risk Factors

A wide range of conditions and factors raise your risk of developing open-angle glaucoma, including:

When diagnosing open-angle glaucoma, an eye specialist—like an optometrist or ophthalmologist—works to rule out other potential causes of symptoms. These include optic nerve and retinal diseases and neurological disorders like multiple sclerosis (MS).

In addition to taking your medical history, they may perform the following tests:

• Dilated eye exam: The provider dilates your pupils, allowing them to view the optic nerve in the back of the eye.
• Gonioscopy: Using a special lens, the provider measures the angle between the iris and cornea.
• Tonometry: Healthcare providers measure intraocular pressure by checking how eyes respond to puffs of air.
• Optical coherence tomography (OCT): Using computerized imaging, providers screen the optic nerve and retina for signs of damage.
• Pachymetry: Healthcare providers use an ultrasound imaging device to measure the thickness of the cornea.
• Slit lamp exam: A slit lamp is a specialized light and microscope that providers use to examine the back of the eye.
• Visual acuity exam: Providers assess how well you see details by asking you to read letters off of charts.
• Perimetry: This is a test that measures your visual field and how well your peripheral vision is working.

Stages of Open-Angle Glaucoma

Based on your test results, healthcare providers may stage the disease based on severity:

• Mild: This stage has no symptoms, but there’s damage to the retinal nerve fiber layer and optic nerve.
• Moderate: Symptoms are present in one hemifield (half of your vision) but not within the central part of where you’re focusing (the point of fixation).
• Severe: Visual symptoms affect both hemifields or start to affect areas close to the point of fixation in one of the hemifields.

There’s no cure for open-angle glaucoma and no way to reverse the vision loss.

As such, treatments, which include medications and medical procedures, focus on slowing the advance of the condition.

Medicated Eye Drops

Prescription eye drops can slow or stop disease progress by helping with fluid drainage or easing intraocular pressure. Eye drops include:

• Prostaglandin analogs, such as Travatan Z (travoprost) and Xalatan (latanoprost)
• Adrenergic agents like Mirvaso (brimonidine) and Iopidine (apraclonidine)
• Beta-blockers, such as Timoptic (timolol) or Betoptic (betaxolol) 
• Carbonic anhydrase inhibitors like Trusopt Ocumeter (dorzolamide) and Azopt (brinzolamide)

Oral Medications

Prescription medications taken by mouth are considered in more severe cases, when eye drops aren’t tolerated or pressure in the eye spikes.

Providers may prescribe the carbonic anhydrase inhibitor Diamox Sequels (acetazolamide) or diuretics (water pills) like Resectisol (mannitol). The goal of both is to reduce eye pressure.

Laser Therapy

Ophthalmologists can use directed lasers, which are strong beams of light, on parts of the eye to relieve intraocular pressure. For glaucoma, there are two main types of laser therapy: laser trabeculoplasty and cyclophotocoagulation.

Laser trabeculoplasty involves directing the laser to the trabecular meshwork, allowing excess fluid to drain out. In cyclophotocoagulation, laser beams target the ciliary body—located just behind the iris—that produces aqueous fluid, reducing its output to relieve pressure. 

Surgery

Eye surgeries for glaucoma work to correct blockages causing elevated pressure in the eye. There are several types of glaucoma surgery, including:

• Trabeculoplasty: This surgery involves creating a flap in the trabecular meshwork to allow fluid to drain.
• Glaucoma implant: Surgeons implant tiny shunts, fluid drainage devices, in a part of trabecular meshwork called the canal of Schlemm.
• Nonpenetrating surgeries: These surgeries focus on promoting the outflow of fluid by removing parts of the trabecular meshwork.
• Minimally invasive glaucoma surgeries: Newer surgeries for glaucoma rely on less invasive techniques to implant shunts or make changes to ease pressure in the eye.

There’s no way to completely prevent open-angle glaucoma. However, early detection and continued treatment can minimize impact and slow the progression of the disease.

You may be able to detect open-angle glaucoma early if your eye health is regularly checked. The American Academy of Ophthalmology recommends the following for eye health screenings:

• A comprehensive eye exam and screening at age 40
• Screening every 2-4 years between age 40-54, every 1-3 years for those 55-64, and every 1-2 years for those for those with risk factors
• More frequent screening in consultation with an ophthalmologist for those at higher risk for glaucoma or other ocular diseases

Especially if untreated, open-angle glaucoma can progress to several more serious complications. These include:

• Loss of peripheral vision: As it damages the retina and optical nerve, open-angle glaucoma can lead to a total loss of side vision.
• Total vision loss: Rarely, open-angle glaucoma progresses to total loss of vision.
• Neovascular glaucoma: Open-angle glaucoma raises the risk of retinal vein occlusion—a blockage of a vein in the retina—which leads to more severe neovascular glaucoma. This causes complete vision loss and eye pain.

Open-angle glaucoma’s effects on vision are irreversible, and the condition is progressive. Researchers found that about 35% of people with untreated cases develop end-stage symptoms within 10 years.

Current therapies are effective, especially if you detect the condition early. Emerging techniques, like those stimulating nerve cell growth, also promise to revolutionize the treatment landscape.

Living with open-angle glaucoma presents challenges and can impact quality of life. Ways to cope may include the following:

• Install brighter lights at home or at work to help with vision loss
• Use magnifying glasses or readers to read texts
• Seek support from family, loved ones, and friends
• Check out social media groups or message boards dedicated to life with vision loss
• Meet with support groups, in person or online
• Seek out advocacy organizations, such as the American Glaucoma Society, National Eye Institute, and Glaucoma Research Foundation