Diffraction always occurs during the propagation of light waves.
Each surface of any IOL (“refractive” or “diffractive”) generates a phase shift in light waves.
ELEVATED PHASE SHIFT * (EPS)
Medicontur‘s proprietary, patented approach to trifocality:
Figure 1: Radial profile with central diffractive phase shift elevated from a destructive level to a constructive interference level.
Figure 2: MTF through focus curves with central diffractive phase shifts at a destructive and a constructive interference level resulting in a 3rd focal point for intermediate vision.