Sometimes i feel like a sudden pain my eye like a piercing but in doesn't last.it's just for one second.why?

See eye doc: May be a dry spot that causes sudden pain. Try using srtificial tears 4 times a day while you wait to see the eye doc.

Dry eye!: This is usually caused by dry eyes! you get a dry spot on the cornea of the eye and then you blink, and as the eyelid rubs over that spot it is like sand paper and causes a short intermittent piercing pain. Then it re moistens and is fine.

Neuralgia: This can be due to the nerves that go through the sinuses that lie behind your eyes. Feels like a spasm and like a needle is pushed through the eye for just a flash of time---not much can be done but some think that sinus medication helps.