Gonioscopy

What is Gonioscopy?

Gonioscopy is a painless examination your ophthalmologist uses to check a part of your eye called the drainage angle. This area lies at the front of the eye, between the iris and the cornea, and it is where a fluid called aqueous humour naturally drains out of the eye. Your ophthalmologist performs gonioscopy to check whether this drainage angle is working properly.

Gonioscopy: What To Expect

During gonioscopy, you rest your head in the chin support of a slit-lamp microscope (the special instrument your ophthalmologist uses to look into your eyes). By this point, your eyes will already have been numbed with drops.

Your ophthalmologist then places a special mirrored contact lens directly on your eye and shines a beam of light into it to highlight the drainage angle. The mirrors reveal this part of the eye, which sits around a corner inside the eye and is otherwise difficult to see.

You may feel the lens touch your eyelashes, but gonioscopy is typically not painful in any way, and it usually takes just a few minutes.

When is gonioscopy used?

Our eyes constantly produce aqueous humour. As new fluid flows into the eye, roughly the same amount should leave through the drainage angle, keeping the pressure inside the eye (the intraocular pressure, or IOP) stable. If the drainage angle is not working properly, fluid builds up, the pressure rises and the optic nerve is damaged. This is often how glaucoma develops.

Your ophthalmologist will perform gonioscopy if certain findings arise during your eye examination. Most commonly, it is done to check for signs of glaucoma: the examination can show whether the drainage angle is too narrow for fluid to drain properly, or whether it is blocked by part of the iris.

Gonioscopy may also be carried out when there are signs of uveitis, eye trauma, tumours or other conditions.

When Should You Have a Gonioscopy?

The early signs of vision changes and eye disease can begin around the age of 40, which is when all adults should have a baseline eye-disease screening with an ophthalmologist.

When screening for glaucoma, your ophthalmologist will perform gonioscopy to check the appearance and function of your drainage angle. Some people are considered glaucoma suspects: they may or may not have higher-than-normal eye pressure, but their ophthalmologist notices other signs that glaucoma could develop. In that case, gonioscopy and other glaucoma screenings are repeated regularly to look for changes over time.

When it comes to protecting your eyesight, time is of the essence. Keep your scheduled appointments with your ophthalmologist — regular examinations can save your vision.

At Athens EyeCare Clinic, we perform all the investigative tests required for suspected glaucoma and drainage-angle dysfunction — book an appointment today.