Ha ! I have a digital rear view, and didn't even know it !

Interesting issue, one that doesn't come up with a conventional rear-view mirror, because there you are focusing on the objects reflected in the mirror, which are several car lengths back, at a good focal distance for the upper portions of your lenses.

Naturally, you replace the mirror with a screen and a camera, and the camera does the focusing and the screen presents the image, and now you have to focus on that.

Gen 2 and Gen 3 Prius went so far as using a mirror in the instrument cluster (I haven't checked if Gen 4 still does) to put it optically farther from your eyes, so there's less focusing effort. The speedometer display is actually down under the dash, and when you look at the gauge cluster, you're looking at a mirror.

 

We have a Rav4 hybrid with the digital rear view mirror which both my wife and I like a lot. It gives a wide bright view that eliminates the pillars. Yes, we both have progressive lenses and the view is a bit blurry but both have gotten used to that. You don't have to have a crystal clear image to see well. So, it is really a matter of what you can tolerate, get used to and accept as tradeoffs. I know some people hate it but not us. Aftermarket ones, btw, are cheap but get mixed reviews of quality.

 

after cataract surgery, i have the progressive lenses mentioned above. without them, i cannot see the radio or hvac controls and settings. speedo is fine, but some of the other info in the cluster would be blurry

 

Yes, the Gen 3 cluster is an interesting design. The speedo is optically farthest from you, because it's reversed inside the dash and you're looking at it reflected in a mirror, so you don't need near focus.

But the warning lights and such are just right there in the cluster, so you need nearer focus for them. If you have the touch-tracer feature, that display is just right behind the (semitransparent) mirror, which is why it appears to float nearer to you than the speedometer.