<prompt> Jacksons cross cylinder test is used for -Subjective verificationSubjective refiningSubjective balancingObjective refining  <response>: Jacksons crosscylinder test : It is used to verify the strength and axis of the cylinder prescribed. The crosscylinder is a combination of two cylinders of equal strength but with opposite sign placed with their axes at right angles to each other and mounted in a handle . The commonly used crosscylinders are of -0.25 D and -0.5 D. Verification of strength of the cylinder. Image: Jacksons cross cylinder Reference : A K KHURANA OPHTALMOLOGY,Edition 4,Page-555 