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Gonioscopy: Don't be afraid of this test that checks the pressure in your eyes!

Dr. Priya Sammani (MBBS)
Medically Reviewed by Dr. Priya Sammani (MBBS) ✓ Medically Reviewed
📅 Updated: Jul 7, 2026 • ⏱ 9 min read • Editorial Policy
Gonioscopy: Don't be afraid of this test that checks the pressure in your eyes!
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Have you ever been to an eye doctor and been told, "The pressure in your eyes seems a little high, let's do a little test"? Or are you a little scared because someone in your family has glaucoma? Today we're going to talk about a very important but very simple test that is done at such times. That is the Gonioscopy test. Although the name is a bit complicated, it is very simple and painless.

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What is Gonioscopy simply?

Simply put, Gonioscopy is a noninvasive test performed by your eye doctor. It basically checks whether the fluid drainage system inside your eye is working properly. It's like checking if a drain is clogged in your house. If this system isn't working properly, the pressure inside the eye can increase, which can lead to serious conditions like glaucoma . So this test is very helpful in detecting such things early.

In what situations is this test performed?

There are several reasons why your doctor may recommend this test. Glaucoma is a disease in which the pressure inside the eye (intraocular pressure) increases, causing damage to the optic nerve, which can lead to gradual vision loss. So, this test can be done anytime there is any suspicion related to it.

This test mainly does:

  • Identify the type of glaucoma: There are two main types of glaucoma. These are angle-closure glaucoma and open-angle glaucoma. Gonioscopy is essential to identify exactly which type you have.
  • Identify other medical conditions: This can also help to rule out other conditions that cause symptoms similar to glaucoma, such as pseudoexfoliation syndrome.
  • Tumors or Cancers Inside the Eye: This test is also performed to confirm if there is a suspicion of a tumor or cancer in the iris (the colored part of the eye).

Remember, if eye pressure remains high for too long, it can cause permanent damage to the eye and even complete loss of vision. That's why tests like this are so important.

How does this Gonioscopy test work?

The science behind this is very simple. Imagine you want to see something that's in the other corner of a room. What do you do? You hold up a mirror and look through it, right? That's the same simple technique used here.

Inside our eyes, behind the cornea (the transparent part at the front of the eye) and in front of the iris, there is a fluid-filled chamber. This is called the anterior chamber . The fluid in this chamber (aqueous humor) is constantly being produced and drained. This fluid drains out of a place called the "drainage angle," where the iris and the white part of the eye (sclera) meet.

The special lens used in gonioscopy uses a magnifying glass or mirror to allow the doctor to see the drainage angle directly. He or she can immediately tell if it is narrowed, blocked, or healthy.

What are the types of Gonioscopy lenses?

There are two main types of lenses used for this test. It is a good idea to know which type of test you are having.

Lens type How it works Commonly used location
Indirect Gonioscopy This lens has mirrors. The light hits those mirrors and is reflected, allowing the doctor to see that angle. At the ophthalmologist's office. This is the most commonly used method.
Direct Gonioscopy This lens does not have mirrors. Instead, it magnifies the light, allowing the doctor to see the drainage angle directly. This is often done in the operating room, along with another surgery.

Do I need to prepare before the test?

Usually, you don't need any special preparation. This is a test that can be done at any time.

But there's one thing: If you wear contact lenses, be sure to ask your doctor if you need to stop wearing them a few days before the test.

If this test is being performed in conjunction with surgery, your doctor will give you specific instructions on how to prepare for it.

What happens during the test?

Let's talk about Indirect Gonioscopy, which you'll likely have to do. It feels like part of a regular eye exam (slit lamp exam).

1. Eye numbing: First, the doctor will put some numbing drops in your eyes. This will numb your eyes. So you won't feel any pain or discomfort.

2. Preparing the lens: Next, the small lens is carefully placed over your eye. Wetting drops are applied to the lens to prevent air bubbles from forming between the lens and your eye and to make it easier to move around.

3. Examination: Now you have seen the doctor use a machine with a big light, a slit lamp, to examine your eyes. He will look into your eye through that lens. At this point, you will be asked to look straight ahead, or the doctor will ask you to look in a direction (up, down, left, right).

4. Dynamic Gonioscopy: Sometimes, the doctor will very slowly push the lens on your eye. This is called dynamic gonioscopy . Don't be afraid, this is to check for any adhesions (synechiae) in the iris.

5. End: The test will be over in a few minutes. The lens will then be removed. You may experience some tearing, which is normal.

This test may or may not include dilating medication. This is determined by the doctor.

Are there any risks or side effects to this?

The good news is that the Gonioscopy test itself has no risks or side effects.

However, due to the use of eye drops to numb the eye and possibly dilate the pupil , you may experience some temporary discomfort, such as blurred vision for a few hours. Your doctor will explain this to you.

If the results are abnormal, what do you do next?

The best thing about this is that the doctor can tell you the results as soon as the test is finished.

If you see a narrowed drainage angle, it means you are at risk for glaucoma. Your doctor will then discuss the treatment you need (eye drops, laser treatment, or surgery).

However, sometimes the angle where this fluid flows can be completely closed. This is called angle-closure glaucoma . This is a medical emergency because it can cause sudden vision loss. If you see this, your doctor will refer you for treatment immediately.

When should I see a doctor?

Glaucoma is a disease that often develops silently, without showing any symptoms in the early stages. Therefore, it is very important to have your eyes checked regularly. It is wise to have your eyes checked at least once a year, especially if you belong to the following risk groups:

  • If you are over 40 years old
  • If someone in the family has glaucoma
  • If you have diabetes (Type 2 diabetes)
  • If you have high eye pressure (ocular hypertension)
  • If you are using corticosteroids for a long time
  • If you have vision impairments that severely affect your vision, such as nearsightedness or farsightedness
Symptom What to do
Talk to your doctor.
Redness of the eyes If you experience one or more of these symptoms, see your eye doctor as soon as possible.
Headache, nausea, and vomiting
Seeing rainbow-like rings when looking at lights
Reduced vision (tunnel vision) or new dark spots
Eye pain or pressure (this usually occurs when the pressure is too high)
Go to the Emergency Treatment Unit (ETU) immediately.
Sudden loss or blurring of vision These can be very serious symptoms. Go to the nearest hospital Emergency Department (ETU) without any delay.
Sudden, severe eye pain (especially with headache and nausea)

💡 Take-Home Message

  • Gonioscopy is a painless, simple, and safe test used to diagnose diseases such as glaucoma.
  • This test only takes a few minutes .
  • Your doctor can inform you of the results as soon as the test is completed.
  • Regular eye exams are very important to protect your eyesight.
  • Sudden loss of vision or severe eye pain is a medical emergency. In such cases, go to a hospital's Emergency Department (ETU) immediately.
Gonioscopy, glaucoma, eye pressure, eye test, glaucoma test sinhala, eye pressure sinhala, drainage angle

❓ FAQ

Frequently Asked Medical Questions (FAQ)

Evidence-based clinical answers to common patient questions

What is Gonioscopy simply?

Simply put, Gonioscopy is a noninvasive test performed by your eye doctor. It basically checks whether the fluid drainage system inside your eye is working properly. It's like checking if a drain is clogged in your house. If this system isn't working properly, the pressure inside the eye can increase, which can lead to serious.

In what situations is this test performed?

There are several reasons why your doctor may recommend this test. Glaucoma is a disease in which the pressure inside the eye (intraocular pressure) increases, causing damage to the optic nerve, which can lead to gradual vision loss. So, this test can be done anytime there is any suspicion related to it.

How does this Gonioscopy test work?

The science behind this is very simple. Imagine you want to see something that's in the other corner of a room. What do you do? You hold up a mirror and look through it, right? That's the same simple technique used here.

What are the types of Gonioscopy lenses?

There are two main types of lenses used for this test. It is a good idea to know which type of test you are having.

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⚠️ Important: Medical articles and information on Nirogi Lanka are strictly for educational and awareness purposes and do not substitute professional medical advice, diagnosis, or treatment. Always consult a qualified physician for any medical concerns.