The sudden onset of very painful symptoms in the eye, this could be a sign of a foreign body or a local inflammation. Therefore, it is important to go to the hospital for a detailed examination when this symptom occurs. If there is a local foreign body, such as a foreign body in the cornea or a foreign body in the conjunctival sac, the foreign body can be removed surgically and the painful symptoms can be reduced. In the case of local inflammation, such as conjunctivitis or keratitis, the correct anti-infective treatment will be chosen according to the specific cause. Another scary situation is that if there is a sudden pain in the eye after internal eye surgery, this may be a sign of intraocular infection. This is a very serious post-operative complication, and once it occurs, it can have an irreversible effect on vision. Therefore, if this symptom occurs after internal eye surgery, it is important to go to the hospital as soon as possible to check and determine the anti-infection treatment to be given afterwards.