I have had this in my left eye for the last week. Advice on this is pretty scarce - the only reference I have found on behind the eye twitching is here. The feeling I get is a vertical twitch going on behind the eye. Like you, there are no signs of this on the outside.

After a few days of twitching I also got a dull ache in the same eye and a very slight change in vision (which could easily have been a speck on my contact lens). I phoned NHS direct who put the fear of god into me and told me to get to A&E immediately (this was because of the change to vision rather than the twitch - if I hadn't have had that they weren't too concerned).

Better safe than sorry I went to Moorfields Eye Hospital A&E. After a 3 hours wait and 5 mins with a doctor he confirmed there was nothing to worry about. Just wear my contacts less and help my eyes by using a hot compress and artifical tears.

Not sure if your situation is the same. My twitch gets worse when I've been working on the laptop for a while. I've never used drugs.

I've done the hot compress thing a couple of times and worn my glasses more and the twitch definitely seems less frequent - but it could be because I've stopped worrying about it.