eye movement during meditation During my past several meditation sessions, which have been getting a little longer (approx 20 minutes now), I have noticed that my eyes twitch and move involuntarily -- it feels similar to the eye movements you can see when people are in REM sleep. 

As far as my meditation is concerned, it feels very distracting -- it typically occurs when I feel like I'm on the precipice of deeper concentration, but it results in so much motion and tension that it typically breaks my concentration.

Has anyone else encountered this before? After googling around, I found one meditator explain that this was a sign of slipping into "trance," not of deeper concentration. Is that a thing? Any thoughts on remedies? Thanks!
If you feel alert, and not sleepy or distracted while it happens, it may be one of the things that naturally occurs as you start to get deeper concentration. 

A number of vaguely unpleasant experiences can spring up- aches, itching, etc.; they come with the territory, and aren't problems in and of themselves, although they may feel frustrating when you're starting to enjoy the sense of concentration.

Take note that it happens, and take note of the feelings of frustration or distraction as they emerge. If you have time, see if you can sit until you get to the other side of it; but don't worry too much if you can't, right away. It's likely a sign that you're doing well, believe it or not.