Yes, it could be very dangerous if you don’t treat it. Cornea is a dome-shaped clear protective covering on the surface of eyes, which is said to be the window of eye. Contact with dust, sands, or a piece of paper can cause cornea scratched or cut. Scratched cornea usually is superficial, named as corneal abrasion in medical terms. Leaving the scratched cornea with no treatment probably lead to corneal ulcer If you feel bad, you could take some actions to help it heal. Use some saline solution to rinse eyes completely. Blink more than normal to help lubricant eyeball and remove small object out of eyes. Try to pull upper eyelids over the lower eyelids so that the lower lashes can help brush foreign objects out. Don’t try to rub your eyes, which makes the scratching worse. Usually uncomplicated scratched cornea will heal in 24-48 hours. Symptoms of corneal abrasion might include grittiness, pain, watering, redness, sensitivity to light, blurry vision and even headache. However if you still feel bad after 24-48 hours, you need to visit your ophthalmologist at your earliest in case it gets to any worse place.