This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Glaucoma, Subject name: Ophthalmology
Von herick's angle grade 3 of anterior chamber denotes 
Select and explain. 
A. Wide open angle, B. Moderately open angle, C. Moderately narrow angle, D. Closed angle
B: Moderately open angle
Answer: B: Moderately open angle 
Explanation: Von Herick's technique compares the depth of peripheral anterior chamber with the corneal thickness. The method involves a narrow slit of light from a slit lamp being projected on to the peripheral cornea at an angle of 60deg as near as possible to the limbus. Ratio Angle closure Angle grade 1:1 open angle VH grade 4 1:1/2 Moderately open angle VH grade 3 1: 1/4 Moderately narrow angle VH grade 2 1: <1/4 angle closure likely VH grade 1