To adjust the centration distance of the phoropter to match the patient's PD, select the CD box as shown below.



 

Selecting the box will turn on the PD LED and insert a graticule lens (Align) in front of each eye. The centration distance is changed by simply rotating the mouse wheel until the lenses are aligned with the centre of the pupils.


To remove the alignment crosses and turn off the PD LEDs, click on any other box, e.g. Sph.