Performing 3-mirror gonioscopy during clinic or a practical exam can be difficult enough without having to remember which mirror sees which structures! Luckily, keeping things straight can be as simple as giving a quick “thumbs up!”
Use your extended thumb to remind you of what each mirror shows. Just think of each mirror as making up 1/3 of your thumb. The most peripheral portion of your thumb is D-shaped, which is also the shape of the most peripherally-focused mirror of the gonioscopy lens. This thumb-mirror shape trend continues with the other two mirrors as shown in the diagram below.
Most of the time, you’ll be using the apical mirror to look at the anterior chamber angle. Having trouble remembering which structures make up the angle? The anterior chamber angle structures from posterior to anterior are as follows: Iris, ciliary body, scleral spur, trabecular meshwork, and Schwalbe’s line. Just remember this highly relatable mnemonic:
“I can’t see the silly line!”
When you look at a mirror in a particular quadrant (e.g., superior), you are actually viewing the opposite part of the retina or angle (e.g., inferior). Because of this, the image you see is upside-down (but is not laterally flipped, as it would be with BIO).
Now you should be ready to do some gonioscopy in clinic! If you haven’t seen the epic 3-D view you get of the posterior pole using the Hruby lens, I suggest you get on it pronto! It is definitely one of the better ways to appreciate the curved shape of the retina. Have any more “handy” memory aids? Share them down in the comments!