Question 15 of 48

(demo test)

The photo shows the following letters:

A. Convergence lever.  When checking near vision, the aperatures of the phoropter are changed so that they are more converged (closer together).  

B. Bubble Level.  The bubble in the level should be in the middle.  This indicates that the phoropter is not tilted.

C. Vertex distance level.  This knob adjusts the forehead plate that touches the patient's forehead.  It determines the distance from the phoropter to the patient.  It is important to keep this distance standard.  Normally, the distance is around 13.75 mm.  You can check this distance by looking in the mirrors on the side of the phoropter.

D. Tilting knob.  This knob is turned to adjust the tilt of the phoropter and make sure it is level.