Eyesight

I moved in my house about six months ago and I could read the company name on the alarm of the house across the road, now it's just a big blurr.

Now I admit I have not done a hell of a lot other than sit in front of a PC for the last few month so I'm wondering if the deterioration would be caused by that, or is it perfectly normal to lose that much sight in six months?

Am I just getting an old git?

36 and I've just had a look. The window is clean and the alarm box is clean too.