Sometimes, it can be difficult to tell if your contact lens is still in your eye or if it has fallen out. Once your eye becomes irritated, you may not know whether the discomfort you feel is being caused by a folded up contact lens that's out of sight or if it is a result of irritation caused by a contact lens that has already fallen out or by your finger as you attempted to search for the missing contact lens. The most important thing to do in this situation is to stay calm. Panicking will not help you find the contact lens any faster.
Cover your right eye to determine if your left eye can see clearly. Then, cover your left eye to test your right eye. If your vision is clear in both eyes, then both contact lenses are in your eyes. If your vision is blurry in either eye, then a contact lens has either slipped to the side or is not in your eye.
Examine your eye in a mirror. If your contact lens is in your eye and hasn't fallen to the floor, you should be able to see it in the mirror. You may need to open your eyes wide or gently pull on your upper and lower eyelids with your fingertips to get a better look around your eye. If your contact lens has folded up or slipped to the edges of your eye, pulling your lids gently open will help you find it.
See your doctor if you believe your contact lens is in your eye, but you cannot find it yourself. It's not possible for your contact lens to be permanently lost behind your eye, but if your contact lens has folded or rolled up and become lodged in your eye, you may need the assistance of your doctor to find it and properly remove it without damaging your eye.