While simple to perform and generally fairly accurate, a recent study has shown that the Van Herick technique for estimating anterior chamber angle depth can be unreliable in some circumstances.
This applies to males and myopes (people with short sight). The other risk factors are when this technique is performed on individuals of Asian and black race.
Click the button to read an abstract of the study:
As such, it is recommended that when examining people in this demographic, a more reliable test is gonioscopy, especially when performed in a dark room.
One system of grading the anterior chamber angle depth is the Shaffer grading system, as depicted below: