Topic: Red eye effect. Why do my eyes glow red in photos? Because there is a devil hidden in you. Stop bluffing. Alright. I will explain. It happens because of blood vessels in our eyes and pupil. Pupil is a small opening whose size is adjusted by the circular muscle called iris. In bright light, the iris contracts making
the pupil smaller. Thus allowing less light to enter into our eyes. In dark, the iris relaxes making the pupil
larger. Thus allowing more light to enter and also exposing the blood vessels in our eyes. Hence, when we take a photo in such a dark environment. The flash of light from the camera floods into our eyes at once. Some of this light gets reflected from the
blood vessels onto the camera before our iris can contract. Making our eyes glow red in photos.