The optical principles of an optometric device: the Jackson cross cylinder (JCC) is discussed. The vector representation of the dioptric power is used to visualize the action of the JCC in each step of the clinical procedure for the subjective determination of an astigmatic refractive error.

Who described JCC technique?

plano to a +4.00 OS sphere combined with -8.00 DC cylinder. The Stokes lens was used in a variation of the present technique by Dennet in 1855. However, the present technique was first promulgated and described by Jackson for the determination of cylinder power in 1887 and for axis in 1907.

How do you use a cross cylinder?

Hold the cross cylinder before the eye with its handle in the direction of the axis of the cylinder in the trial frame. Rotate the cross cylinder, first one way then the other. This changes the action of the combined cylinders, and shifts the axis of the combination, first one way then the other.