Normally when I take a picture of my cat using the Flash both of his eyes reflect green, Which is common for cats. However the other night his one eye was bothering him and when I went to try to take a picture to show the vet it actually reflected red!
Now in my case I already knew there was an issue with the eye as this is a reoccurring condition for him. Earlier this is how he was holding the eye -notice that it is shut-
A trip to the vet and some eye stain later confirmed what I already suspected-he had abraded his eye and it was bothering him. I showed the vet the picture and he said the irritation has inflamed the blood vessels in the eye causing them to reflect red. So if you take a picture of your cat and the eyes are different colors, get it checked out in case it needs treatment!