The optics of this IOL are magical. My understanding of them is partial and maybe by writing this they’ll come into better focus for me.
Typical IOLs (not this one) bring things into focus at a limited distance or range. The natural eye focuses actively on a distance by squeezing the natural lens, changing its shape, changing the focus point. The plastic IOL cannot do that. So an IOL has a corrective prescription (or refraction) built in.
Instead, my IOL will have three distances (thus “trifocal”) it will focus. (Each is actually a range, not just a single distance.) The corrective prescription for my far-vision is built into one of the concentric rings of the lens. The prescription for mid-vision is in the next concentric ring. And for near-vision, into the next ring. Then this far-mid-near ring pattern repeats across the active area of the IOL.
When I’m standing looking at something on the far horizon, only my far-vision rings produce a sharp image. The mid- and near- images of objects on the horizon are not focused on my retina, and my brain will learn to ignore them in favor of the far- image.
When I’m reading something up close, the near-vision rings are providing the sharp image on my retina. The other rings are providing out-of-focus images, and similarly my brain will learn to ignore them when I want to read.
What are those little wings? Apparently they keep the lens in place in the center of the pupil. Who knew?