You can conduct compression/indentation only with a G4 (4 mirror) or G6 (6 mirror) lens without a flange. The non-flanged version of the G4 and G6 lenses do not require any coupling fluid, however, many customers do prefer to use artificial tears. You can use the G4 or G6 no-flange contact element to gently apply pressure on the eye and open up the angle. if you have a patient with a suspected closed angle, the indentation procedure is a great way to determine the level of closure, temporarily relieve pressure, and examine any troublesome synechiae requiring intervention.