What Is Open-Angle Glaucoma? Symptoms and Treatment

Contents hide

1. Introduction

2. What Is Open-Angle Glaucoma?

3. How Common Is It?

4. Causes and Risk Factors

5. Symptoms of Open-Angle Glaucoma

6. How Open-Angle Glaucoma Is Diagnosed

7. Treatment: Controlling the Pressure to Protect Vision

8. Living with Glaucoma

9. Can Open-Angle Glaucoma Be Prevented?

10. Key Takeaways

11. Frequently Asked Questions (FAQ)

Introduction

Open-angle glaucoma, also known as primary open-angle glaucoma (POAG), is a chronic eye disease that gradually damages the optic nerve, the pathway connecting the eye to the brain.

This condition develops slowly and painlessly, often without noticeable symptoms until it is advanced. For this reason, it is sometimes called the silent thief of sight.

Regular eye exams and ongoing treatment are essential for preserving vision and preventing permanent blindness. Routine checkups help catch diseases early, so treatment can begin as soon as possible.

What Is Open-Angle Glaucoma?

Glaucoma refers to a group of eye diseases that cause progressive damage to the optic nerve, typically associated with elevated intraocular pressure (IOP).

In open-angle glaucoma, the drainage angle of the eye, which is the space between the cornea and iris, stays open. However, the trabecular meshwork, which is the eye’s drainage system, does not work as well as it should.

As a result, the fluid in the eye, called aqueous humor, drains too slowly. This causes pressure to build up inside the eye. Over time, the increased pressure damages the optic nerve fibers and leads to a gradual loss of side vision.

How Common Is It?

Open-angle glaucoma affects more than 70 million people worldwide. It is the leading cause of irreversible blindness.

The risk of open-angle glaucoma increases after age 40. Up to 10% of people over age 70 are affected.

People with a family history of glaucoma, those of African or Hispanic descent, and people with high eye pressure are at higher risk.

Causes and Risk Factors

The exact cause of open-angle glaucoma is not fully understood, but several factors can increase the risk:

1. Increased Intraocular Pressure (IOP)

When the fluid inside the eye cannot drain properly, pressure builds up, damaging the optic nerve.

2. Age

Open-angle glaucoma is most common after age 40. The risk doubles with each decade after age 60.

3. Genetics and Family History

Having a parent or sibling with glaucoma increases the risk by up to nine times.

4. Race and Ethnicity

Open-angle glaucoma is more common and often more aggressive in people of African descent.
It also tends to develop at a younger age in Hispanic populations.

5. Systemic Diseases

Diabetes
High blood pressure
Sleep apnea

6. Long-Term Corticosteroid Use

Steroid eye drops or oral medications can increase eye pressure over time.

7. Thin Cornea or High Myopia

Certain structural features of the eye, such as a thin cornea or severe nearsightedness, can increase the likelihood of optic nerve damage.

Symptoms of Open-Angle Glaucoma

One of the biggest challenges with open-angle glaucoma is that it does not cause symptoms for many years.
By the time symptoms appear, the optic nerve is often already damaged.

Typical signs may include:

Gradual loss of peripheral (side) vision
Difficulty seeing in dim light
Needing more light to read
Blurred vision in later stages
Tunnel vision (advanced disease)

Central vision usually stays clear until the late stages. Many people do not know they have glaucoma until significant damage has already happened.

How Open-Angle Glaucoma Is Diagnosed

The only way to detect glaucoma early is with a comprehensive eye exam.

1. Intraocular Pressure Measurement (Tonometry)

Determines if the pressure inside the eye is above normal (typically > 21 mmHg).

2. Optic Nerve Evaluation (Ophthalmoscopy)

The doctor examines the optic disc for signs of cupping or thinning of the optic nerve.

3. Visual Field Test (Perimetry)

Maps the patient’s side vision to detect early defects.

4. Optical Coherence Tomography (OCT)

Provides detailed images of the retinal nerve fiber layer to monitor progression.

5. Gonioscopy

This test checks that the angle between the iris and cornea is open, which helps tell open-angle glaucoma apart from angle-closure glaucoma. Adults should have a comprehensive eye exam every one to two years starting at age 40.
People at higher risk, such as those with a close family member with glaucoma, people of African or Hispanic descent, or those with high eye pressure or diabetes, should start screening before age 40 and have exams every year or as recommended by their eye doctor.
Early and regular screening helps find glaucoma when it is easier to treat.

Treatment: Controlling the Pressure to Protect Vision

The main goal of treatment is to lower eye pressure to a safe level and prevent further damage to the optic nerve.

Glaucoma cannot be cured, but with the right treatment and regular follow-up, its progression can be slowed or stopped.

1. Eye Drops (First-Line Therapy)

These drops lower eye pressure by either reducing the amount of fluid the eye makes or by helping the fluid drain out better.

Common types:

Prostaglandin analogs (latanoprost, travoprost)
Beta-blockers (timolol)
Alpha agonists (brimonidine)
Carbonic anhydrase inhibitors (dorzolamide)

Most people start treatment with eye drops. It is important to use them exactly as prescribed. Common side effects include redness, stinging, or discomfort. If you notice any side effects or have concerns, talk to your doctor so your treatment can be adjusted if needed.

2. Laser Treatment (Selective Laser Trabeculoplasty – SLT)

This is a painless outpatient procedure that uses laser pulses to help fluid drain better through the trabecular meshwork.

Laser treatment usually lowers eye pressure by 20 to 30 percent.
It can be used instead of eye drops or together with them.

3. Surgical Treatments

If medications and laser treatments do not lower eye pressure enough, surgery may be needed.

• Trabeculectomy

Creates a new drainage pathway for fluid to exit the eye.

• Tube Shunt Surgery

Places a small tube implant to direct fluid away from the eye.

• Minimally Invasive Glaucoma Surgery (MIGS)

Newer techniques use small stents, such as iStent or Hydrus, to help fluid drain out of the eye and allow for a quicker recovery.

Living with Glaucoma

Because open-angle glaucoma is a lifelong condition, people with this disease should:

Apply eye drops daily as prescribed.
Attend regular checkups for pressure and visual field tests.
Monitor side effects or changes in vision.
Inform doctors about all medications, especially steroids.

Managing glaucoma is a long-term partnership between you and your eye doctor. You may need to make some changes to your daily routine, such as avoiding activities that strain your eyes and making sure your eye doctor knows about all the medicines you take.
Vision changes can affect driving, work, and other daily activities, so it is important to be prepared and talk to your doctor about any concerns.

Can Open-Angle Glaucoma Be Prevented?

Open-angle glaucoma cannot always be prevented, but you can lower your risk and catch it early by:

Having regular eye exams after age 40
Protecting your eyes from injury.
Keeping your blood pressure and blood sugar at healthy levels.
Avoiding long-term or excessive use of steroid medications.
Encouraging your family members to get screened for glaucoma.

Key Takeaways

Open-angle glaucoma is the most common type of glaucoma and often has no symptoms at first.

It causes vision loss that gets worse over time and cannot be reversed. It usually starts with loss of side vision.

Early detection through regular exams is crucial.

Treatment focuses on lowering eye pressure with drops, laser therapy, or surgery.

With regular care, most people with glaucoma can keep useful vision for life.

Frequently Asked Questions (FAQ)

1. Is open-angle glaucoma curable?
No. Damage to the optic nerve cannot be reversed, but early and ongoing treatment can help control the disease and slow its progression.

2. Does glaucoma always cause high eye pressure?
Most cases of glaucoma involve high eye pressure, but some people develop glaucoma even when their eye pressure is normal. This is called normal-tension glaucoma.

3. Can I use my drops irregularly?
No. Skipping doses can cause your eye pressure to rise and may speed up vision loss.

4. Is laser treatment permanent?
SLT can work for several years and can be repeated safely if your eye pressure goes up again.

5. Can lifestyle changes help?
Yes. Regular exercise, eating a healthy diet, and avoiding smoking or stress can help support your eye health.

References

American Academy of Ophthalmology (AAO). Primary Open-Angle Glaucoma Preferred Practice Pattern®, 2023.
National Eye Institute (NEI). Facts About Glaucoma.
European Glaucoma Society (EGS). Guidelines on Glaucoma Management, 2021.
World Health Organization (WHO). Vision 2020: The Right to Sight – Global Initiative for the Elimination of Avoidable Blindness.
Weinreb RN, et al. The Pathophysiology and Treatment of Glaucoma: A Review. JAMA, 2014.