Gonioscopy is an eye test that checks for signs of glaucoma. It uses a special lens and slit lamp to evaluate your eye’s drainage angle (anterior chamber angle). If the drainage angle is blocked or closed, you may have glaucoma. Gonioscopy is one of many tests you may need if you are at risk for glaucoma.
This test checks whether your eye’s drainage system (anterior chamber angle) is working properly. Gonioscopy is one of many tests that eye care specialists (ophthalmologists) use to detect glaucoma. Gonioscopy helps determine which type of glaucoma you have and guides treatment decisions.
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This structure is near the front of your eye. It's between the colored part of your eye (iris) and the protective outer layer (cornea). The drainage angle enables fluid inside your eye (aqueous humor) to drain.
If the drainage angle is blocked, your eye cannot clear fluid. This causes fluid and pressure to build up within the eye. Over time, this can lead to glaucoma, optic nerve damage and blindness. The drainage angle is challenging to access, which is why gonioscopy is necessary.
This test is especially helpful in detecting:
This test may be right for you if you have glaucoma risk factors. These include:
The test uses a lens with special prisms and a slit lamp (type of microscope) to determine whether the drainage angle is open or closed. It also checks for:
It’s possible to use imaging studies such as ultrasound and optical coherence tomography. But these methods are more costly than gonioscopy. They also don't provide the same level of detail.
Gonioscopy is not used as often as it could be. It requires special techniques that take time to learn. If you need this test, it’s best to receive it from an experienced ophthalmologist.
There is not much you need to do to prepare. If you wear contact lenses, you will need to remove them. You will not be able to put them back in until an hour after the exam. You may wish to bring glasses with you if you cannot see without corrective lenses.
The test is painless. You receive medications that numb your eye to help you stay comfortable. You may feel pressure on your upper eyelid as the ophthalmologist places the gonioscopy lens on your eye.
Your ophthalmologist may use a lens that has three or four mirrors in it:
Here’s what happens:
Your ophthalmologist will let you know the results immediately.
Your care may also include:
A note from Cleveland Clinic
Gonioscopy is an eye test that ophthalmologists use to check for signs of glaucoma. This test provides detailed information that can help confirm a glaucoma diagnosis. It also enables you to receive the appropriate therapies for your needs. Gonioscopy is quick and painless. For best results, it’s essential to receive care from an experienced ophthalmologist.
Last reviewed by a Cleveland Clinic medical professional on 02/16/2022.
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