The diffractive multifocal IOL is designed to use both diffractive and refractive optics to provide distance, intermediate and near vision. The central portion of the lens has a series of steps that are carved in a very precise arrangement with varying step heights and distances between steps. Each of the steps of this diffractive optic bends the incoming light differently, creating a near focus that is quite separated from the distance focus formed by the remaining refractive portion of the lens. This large separation between the two images allows for less artifacts or distortion in either of the images, providing good quality of vision at both distance and near.
Diffractive Multifocal IOL
The diffractive multifocal IOL provides distance vision through the refractive portion of the lens. The image formed from a distant object through the central diffractive portion of the lens is well separated from the retina, located in front of the retina in this case. Thus, at the retina the only image in sharp focus is the distance image.
When looking at near objects, the image formed by the central diffractive portion of the diffractive multifocal IOL is focused at the retina. The image formed by the refractive portion of the IOL is well separated from the retina, located way behind the retina in this case. Thus, at the retina the only image in sharp focus is the near image.