Eye injuries should always be shown to a doctor as soon as possible. The ways in which the eyes can be damaged are many, and not all of these have obvious symptoms. The degree of redness is not any indication of seriousness, and although pain and blurry vision are usually reliable indicators, the retina and the vitreous humour lack nerve endings. Damage to these areas will therefore not cause pain.
If your daughter has no other symptoms such as pain, a scratchy sensation, blurry or double vision, or a change in the shape or size of the pupil, it is likely that she has a minor injury such as a subconjunctival hemorrhage. This is simply a burst blood vessel on the surface of the eyeball. Such an injury may look and sound serious, but does not require medical attention and will heal on its own within a week or two. For a few days, keep your daughter away from smoke and dust, and tell her not to rub the eye.
However, if other symptoms do exist, your daughter certainly should see a doctor immediately. These may indicate corneal damage or an internal injury. Some such injuries are not accompanied by pain, and vision may be noticeably affected only with the passage of time.
answered by G M