I had 20/20 vision until I was 33, then over the next couple of years I noticed my site getting worse until I tried on a friends pair of glasses and everything

I had 20/20 vision until I was 33, then over the next couple of years I noticed my site getting worse until I tried on a friends pair of glasses and everything went crisp. I asked the optometrist what would cause my eyes to go bad and she just said "How many hours a day do you look at a computer screen?"