How do such devices affect eyesight? Is the leneses not "zooming in" to see "far objects" harmful? How does it compare to using flat screens? I suppose it's fi

How do such devices affect eyesight? Is the leneses not "zooming in" to see "far objects" harmful? How does it compare to using flat screens? I suppose it's findable on the Internet and I am planning to search that info later, but here seem to be knowledgeable folk, so I'd also like to hear your thoughts