Most doctors document gonioscopy results by using two crossed lines in the shape of an “X” to represent the four quadrants of the anterior chamber.
In most people, the angle in the inferior quadrant is widest and the normal iris configuration is slightly convex. In patients with hyperopia, the iris may have an even more convex insertion. Conversely, myopic patients will usually have a more concave insertion.
If visualization of the angle anatomy is difficult, have the patient look in the direction of the mirror being used.
Because the gonioscopy procedure can result in a temporary reduction in intraocular pressure, it is usually best to obtain the measurement before performing gonioscopy.
When performing gonioscopy in patients with narrow angles it is more effective to decrease the room illumination and examine the angle when the pupil is larger. Bright illumination may constrict the pupil and widen the angle and lead to an inaccurate assessment of anterior chamber angle width.
Patients with a recent history of blunt force ocular trauma are susceptible to angle recession or iris tears. In these cases, gonioscopy should be delayed until the eye has stabilized. Gonioscopy should not be performed in patients with a recent hyphema or suspected globe/corneal perforation.
All patients with a history of anterior uveitis should have gonioscopy performed to rule out the presence of peripheral anterior synechiae.
All patients with a history of ischemic eye disease should have gonioscopy performed the rule out the presence of neovasularization of the angle.
- Branch retinal vein occlusion
- Central retinal artery or vein occlusion