# Red-Eye in Photos (Revisited) **URL:** \ **Category:** Factual Questions\ **Created:** [August 16, 2005, 11:24am UTC](https://boards.straightdope.com/t/red-eye-in-photos-revisited/317250 "2005-08-16T11:24:33Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Bear\_Nenno](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bear_nenno/32/3358_2.png) [@Bear\_Nenno](https://boards.straightdope.com/u/Bear_Nenno)\ **Post date:** [August 16, 2005, 11:24am UTC](https://boards.straightdope.com/t/red-eye-in-photos-revisited/317250/1 "2005-08-16T11:24:33Z")
There are several threads already on the subject of Red Eye, it’s causes, and prevention. And though I found one or two comments that darker eyes are less prone than blue or gray eyes, but nothing really as to WHY. So why is it that darker eyes would reflect less of the flash? Isn’t everyone’s pupils the same? Just the iris is different, right? Is some light reflected through the iris as well as the pupil? My Korean friend says that Koreans never get red eye in pictures. Is this accurate? If so, why? ---
**Author:** ![TellMeI\_mNotCrazy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tellmei_mnotcrazy/32/3419_2.png) [@TellMeI\_mNotCrazy](https://boards.straightdope.com/u/TellMeI_mNotCrazy)\ **Post date:** [August 16, 2005, 12:20pm UTC](https://boards.straightdope.com/t/red-eye-in-photos-revisited/317250/2 "2005-08-16T12:20:18Z")
Lighter colored eyes tend to have less melanine in them, meaning more light passes through them to the back of the retina, illuminating the blood vessels there. The way red-eye reduction works is firing a few flashes of light at the eye (it works best if the subject actually looks at the flash), thereby dilating the pupil, and allowing less light to pass through. ---
**Author:** ![don\_t\_ask](https://avatars.discourse-cdn.com/v4/letter/d/e68b1a/32.png) [@don\_t\_ask](https://boards.straightdope.com/u/don_t_ask)\ **Post date:** [August 16, 2005, 12:37pm UTC](https://boards.straightdope.com/t/red-eye-in-photos-revisited/317250/3 "2005-08-16T12:37:03Z")
> [@TellMeI'mNotCrazy](#): > > Lighter colored eyes tend to have less melanine in them, meaning more light passes through them to the back of the retina, illuminating the blood vessels there. The way red-eye reduction works is firing a few flashes of light at the eye (it works best if the subject actually looks at the flash), thereby dilating the pupil, and allowing less light to pass through. The opposite - **constricting the pupil**. ---
**Author:** ![TellMeI\_mNotCrazy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tellmei_mnotcrazy/32/3419_2.png) [@TellMeI\_mNotCrazy](https://boards.straightdope.com/u/TellMeI_mNotCrazy)\ **Post date:** [August 16, 2005, 12:38pm UTC](https://boards.straightdope.com/t/red-eye-in-photos-revisited/317250/4 "2005-08-16T12:38:50Z")
Sorry - that’s what I get for trying to think on a caffeine slump. ---
**Author:** ![Rufus\_Xavier](https://avatars.discourse-cdn.com/v4/letter/r/eada6e/32.png) [@Rufus\_Xavier](https://boards.straightdope.com/u/Rufus_Xavier)\ **Post date:** [August 16, 2005, 1:16pm UTC](https://boards.straightdope.com/t/red-eye-in-photos-revisited/317250/5 "2005-08-16T13:16:07Z")
Perhaps south of the equator, it works in reverse. 😉 ---
**Author:** ![TellMeI\_mNotCrazy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tellmei_mnotcrazy/32/3419_2.png) [@TellMeI\_mNotCrazy](https://boards.straightdope.com/u/TellMeI_mNotCrazy)\ **Post date:** [August 16, 2005, 1:20pm UTC](https://boards.straightdope.com/t/red-eye-in-photos-revisited/317250/6 "2005-08-16T13:20:41Z")
> [@Rufus Xavier](#): > > Perhaps south of the equator, it works in reverse. 😉 Exactly. I believe it’s called the Cornealis Effect or something…