Therefore, when your eyes fill with tears, such as when you cry or cut an onion, most of that fluid ends up in your nose. If you look directly at the camera during a flash photo, the light from the flash entering your eyes may reflect off the retina, as if reflecting off a mirror. The back of the eye contains many small blood vessels, which give it a reddish appearance. Therefore, the reflected light looks red. To prevent this reflection from ruining their photographs, professional photographers use a flash that is not exactly in line with the camera.
Amateur photographers can ask their subjects to look slightly to the side of the camera.
A contact lens that slips off the corneal surface of the eye and moves under the eyelid cannot go far. The conjunctiva, a clear lining that covers the inner surface of the eyelids, forms a small sac or pouch between the eyelid and the eye to contain the eye's tears. Usually you can gently manipulate the contact lens back into place. If the lens is difficult to retrieve, you may need to flush your eye with sterile saline. Sometimes part of your eyelid may twitch for several minutes or hours.