A crossed cylinder (cross-cyl, or x-cyl) lens is used to find, subjectively, the astigmatic component of a patient’s prescription. This will be after retinoscopy is done or best sphere is determined.
The cross-cyl lens is mounted in a rim with a handle. The lens is formed from a plus cyl at right angles to a minus cyl of equal power. The axis of a cross cyl is at 45° to the axes of the cyls, and this is in line with the handle. The axes of the cyls are marked, and normally engraved with their powers.
Cross cyls are available in powers of +/- 0.25, +/- 0.50 and +/-1.00.
