Duochrome Testing Let's determine whether to refine the spherical end or not with Duochrome test Test one eye at a time. If you wear glasses or contact lenses wear them for the test Hold the screen about 40 cm or 15 inches away Try to identify if the two images are same or different. Close your Left Eye Which square is different? Clear on Red Side Clear on Green Side Both Get Equal Clarity Left Eye Add minus power to refineLeft Eye Add plus power to refineLeft Eye No refinement required Close your Right Eye Which square is different? Clear on Red Side Clear on Green Side Both Get Equal Clarity Right Eye Add minus power to refineRight Eye Add plus power to refineRight Eye No refinement required