When does an eye twitch indicate something neurological going on? difference between normal eye twitch and neurologically caused one?

Benign twitch: All twitches are caused by muscle spasms. A mild twitch that you feel but does not hurt, or that you may barely notice in a mirror, is usually caused by fatigue or stress and goes away on its own. If it persists for more than several days, becomes painful, or makes it difficult to open or close your eye, it should be evaluated by a neurologist or ophthalmologist.