Hi - i've been having this vision problem lately and i don't know if
it's anything to be worried about - i'm a bit of a
hypochondriac...Anyhow, just some background first, i am a web
developer and spend most of the day in front of a computer - at least 8
hours / day.  I also do freelance so sometimes i'm on most of the
weekend.  I am 28 and have had the same glasses prescription for about
8 years.

Lately i've been having this problem where if i'm in a situation where
there is nothing to 'occupy' my vision (i.e keep my eyes moving), my
eyes almost seem to get tired and want to focus on a random object.
For example, if i'm in my car @ a stoplight, my eyes might relax and
'focus' on the license plate of the car in front of me, and gradually
'relax' and start to blur slightly.  It's a weird feeling.  I'm very
aware of this while it's happening, and i can stop it by looking away.
It happens quite a few times a day, i've been dealing with some other
medical issues lately so i've been particularly sensitive to things
going on with my body - so i don't know if this is something that has
always been there and i'm just noticing it now or what.  

Help!