Cross cylinders is
A i.e. One plus cylinder and one minus cylinder of equal strength Cross cylinder is a combination of two cylinders of equal strength but with opposite sign placed with their axis at right angles to each otherQ and mounted in a handle. Jackson's cross cylinder test is used to verify the strength & axis of the cylinder prescribed. The commonly used cross cylinders are of +- 0.25 D and -0.5 D.
One plus cylinder and one minus cylinder of equal strength
One plus cylinder and one minus cylinder of unequal strength
Two plus cylinders
Both minus cylinders
One plus cylinder and one minus cylinder of equal strength