LS Answers: Why do we get red eye in flash photography?

Share Post To:
  •  
  •  
  •  
  •  
  •  
  •  

So, you’re dolling yourself up for yet another undoubtedly incredible night at Halo and want to snap that all important profile picture, only to find that when you take a look on Facebook the next morning, your eyes look like they have been grasped straight from an extra of Buffy the Vampire Slayer! The unflattering red eye effect from flash photography is a common occurrence in our pictures and whilst many of us may find it a hindrance, its absence can be a signal of some serious consequences.

Our eyes use mechanisms which utilise the pigmented sections of the eye, which is influenced by the lighting in our surroundings. For example, in poor light our pupils dilate, or get bigger. However when an eye is subjected to too much light, the pupillary light reflex occurs whereby the iris will direct the pupil to contract in a circular motion, making the pupil smaller.

When a bright light flashes quickly in front of us, our eyes do not have the time to complete this mechanism and therefore the light can reflect off our retinas which is the light-sensitive tissue that lines the inner surface of the eye. As our retinas are rich in blood vessels, the colour reflected back from them is the vivid red which we witness in photographs. The reason why the amount of red reflected from the eye varies between individuals is because people with light eyes have lower levels of melanin which in turn absorb less and as a result reflect back more light.

A dramatic consequence of lacking a red eye effect in a photograph is that it is can be used as a diagnostic tool in determining a rare, cancerous tumour in young children named a retinoblastoma. Usually patients present with a white eye or cat eye effect.  Fortunately, if the condition is spotted early and presented to a doctor, the tumour can be combated in numerous ways and studies have shown that ‘98% of children are successfully treated’.

You may also have noticed that our feline friends have an equally eerie phenomenon when presented with a flash as their eyes shine back a bright white light.  This difference in colour is due to the fact that animals such as cats, dogs and deer posses a reflective layer named the tapetum lucidum which acts like a mirror in their eyes.

To avoid this satanic predicament, you can simply turn the lights on in a room so that your eyes can adjust before the intense burst of light but if unable to do so, fear not, as luckily nowadays dilemmas such as this can be remedied with a cheeky instagram!

Hayley Williams

Leave a Reply