<prompt> The optical procedure being done is used for:Objective refractionSubjective adjustment of cylinderBinocular balancing of visionSubjective refinement of cylinder  <response>: Ans. d Subjective refinement of cylinderRef: Khurana optics 2e, p. 153The instrument seen in the image is the Jackson cross cylinder over the trial frame - which is used for subjective refinement of cylinder. 