Most of the time I can see very well, but I can't anticipate when I will be able to see and when I won't. (I have Age-related Macular Degeneration).
This makes using screens difficult when there is not enough contrast - bank ATM's, mobiles, texting, It is a bit like when you come indoors from bright sunshine and momentarily you can't see much, but it can happen to me at anytime and my eyes don't adjust quickly. If the weather changes suddenly which it does often in UK, I might not be able to see for a bit, or driving along I come into an avenue of trees or the sun comes out from behind a cloud or....
I noticed on our trip in February that I could read some road signs perfectly well, then change direction and not be able to read the next one at all - it would be blank - even huge motorway signs. And sometimes, a grey car on a grey road is all but invisible. A deciding moment came when I was approaching traffic lights and couldn't tell which one was lit. No amount of looking harder made any difference. (Fortunately I was in the passenger seat at the time.. but it scared me!)
So I've had to give up driving. You can't drive when you can only see some of the time.
There have been tears..
(But don't send me sympathy, though I really appreciate your kindness, as it will just make me teary and then I won't be able to see what you have written!)