#36 Theory Behind The Red–Eyed Photos
Ever wondered why your eyes appear red in some of your photos? Using flash is normal when clicking photos in a dark environment. The flash hits the eyes and reflects from the retina to give a red-eye effect to your photographs.
However, the red eyes aren’t restricted to the flash problem and may occur due to several other reasons, like some sort of serious eye illness, a cataract or even a retinal detachment. Thankfully, the most common reason for the spooky eyes is much more benign.