Cross-eyed

My eyesight was good when I was young, but starting in high school, one eye's vision slightly worsened, and I noticed a difference in vision between both eyes. However, since I see the world with my better eye, I don't experience significant discomfort.

But definitely, as I approach my 40s, I start to have trouble seeing even small text in news that I could see clearly from afar.

Is presbyopia when you have trouble seeing things up close and can see distant objects clearly?

Since I spend a lot of time on my phone, I also think it might be bad for my eye health.

I probably can't improve my eyesight.

What should I do to improve eye health?