Why do we get red eyes in some pictures with flash?

Why do the eyes appear red in some photographs?
The " red-eye effect " usually occurs when the flash is used at night or in very dim light . The light emitted by the camera is reflected in the back of the retina and it is captured. Why red? Because the light that comes back to the face is the reflection of the numerous blood vessels of a membrane called choroid that is in the retina, that's why it has that red hue. Pretty disturbing.

Those with dark eyes are less likely to appear with red eyes because they may have enough dark pigment to not reflect the reddish hue.

When does it appear?

When we use flash and we look directly at the lens of the camera and therefore its light is reflected directly on our retina.
It should be noted that it can also occur although we are on the side if we have dilated pupils .

So, if I turn off the flash, will my eyes have less red?
Of course, if there is enough light to not use the flash, turn it off and you will completely avoid the "red eye effect".

How do I avoid appearing with red eyes?
We present 3 tips so that your eyes do not seem "diabolical" when there is no other choice but to use flash.

1. Avoid looking directly at the camera
   You do not have to turn your head completely, just look a little beyond the lens or to one side so that your eyes do not catch the camera's flash at too direct an angle.

2. Enlighten the environment as much as you can
   If the place where you are is really dark , you will have very dilated pupils and this increases the "red eye effect". Therefore, look how to light up the place a little more and there will be less chance of showing your most terrifying side.

3. Do you have an anti-red eye option? Activate it!
   This function helps to avoid red eyes using shorter and faster flashes just before the camera takes the picture.
   This small lapse of time allows the pupil to contract and the flash of fast flashes does not allow it to expand too much again. This diminishes the options of going out with red eyes.

Why, sometimes, in group photographs only some people come out with red eyes?
Surely you have ever found that you are the only one or the few that in a group picture appears with eyes like two radioactive tomatoes. There are several reasons why this may occur.
Generally it is because we are the ones who have looked most directly at the camera and we were in a straight line with it. You may also have more dilated pupils and, therefore, the light will affect and reflect more in your eyes.

Sometimes only one of our eyes appears with this color. This may be because one eye has a slightly different angle to the other or, perhaps, to some type of ocular pathology . In case this happens to an elderly person repeatedly, it is possible that it is a case of cataracts .