A sudden pain in the eye followed by a return to normal may be visual fatigue, dry eye, or neuralgia. If there is a sudden pain in the eye followed by other abnormalities, such as significant congestion in the eye, you may have conjunctivitis or keratitis. If there is persistent swelling and pain in the eye and blurred vision, it may be an attack of glaucoma. When there is sudden pain in the eye, pay attention to rest and it is not advisable to use eye strain again. If the symptoms do not improve through rest, or if the eyes still show abnormalities, go to the local eye clinic for further examination in a timely manner. Pain caused by visual fatigue and dry eye can be treated by ordering artificial tear drops. Those caused by inflammation are generally further treated with antibiotic eye drops.