Hiking is good for you physically, helps lower weight, increases physical fitness, etc. etc…so there is some benefit to the eyes also.
It does like Grampie said create another whole set of problems-----that is if you don’t do it right----too much, too heavy, too soon, too fast, too many miles, etc.
The lenses in our eyes become less fexible as we age, so we start having problems seeing things up close and focusing on them in our 30’s and 40’s.
Don’t think reading or computer work or any other kind of close in work requiring eyes to be focused is bad for the eyes and causes them to go bad, that is if the work is done right. Glare is a problem. Take breaks, every 15 minutes or so, look away, etc.
The lenses in the eyes focus using muscles to help them adjust for seeing things in close and things farther out. So it seems logical that if you exercise these muscles by looking close in, then looking farther out----that these muscles will become strongers and your eyes will be able to better focus on things. Hence the looking at your computer, then looking away thing, etc. Hope this helps.
See you out there.:cheers
Maintain