I also have some similar problems with vision, but I think they may possibly be drug related (either from beta-blockers, gabapentinoids or cannabis - cannabis certainly has this effect in the short term). On the other hand, I may be just focusing on things I had not previously noticed. I now get neurotic about my vision, so it's hard to tell.
It sounds like you are describing tunnel vision, a partial loss of peripheral vision or some kind of cortical vision impairment. There are serious and benign causes. I think it is normal to only be able to read the line of text you are looking at, but it would be abnormal to not be able to see the other lines in the periphery whatsoever.
A couple of basic online tests you could do are the amsler grid and a visual field test (the one at testvision.org is good).
If you have not had one recently you probably should get an eye test, especially if the problem is worsening.