Don't be so hard on yourself - I do totally the same thing sometimes......I'm trying to read someones post and I just blank out or the words just won't come together to make a sentence...or everythings fuzzy. Sometimes I find it easier to read with the light on in the day because the darker it is the more "intense"??? the screen is (too white if ya know what I mean) , other times I just have to switch off and come back later. I hope you do manage to read some of the posts on here. A LOT of people who suffer from depression/bipolar find it hard to concentrate , that is why you need to get that help I was on about on your other thread.
Look after yourself ,
Smiler 