With the help of Gonioscope, your doctor performs a painless exam called Gonioscopy. With this test, your doctor checks a part of your eye called the drainage angle. This part is at the front of your eye between the iris and the cornea. It is where fluid called aqueous humor naturally drains out of your eye. Your ophthalmologist will perform a Gonioscopy to check to see if this drainage angle is functioning properly.