Expert reveals why some people have grey eyes and it's related to the sky

A few days ago, a doctor revealed the secret of blue-eyed people. In a previous article, we told you about this mutation of European origin. Today, we're going to take a look at an even rarer iris colour: grey.

Why do some people have grey eyes?

The colour of our irises can change over the course of our lives. For example, some people may be born with blue eyes, only to see them turn brown. Similarly, heterochromia (more commonly known as "minnow eyes") gives some people different iris colours (one green eye, one blue eye, for example).

But more generally, it's melanin that defines our eye colour. As VisionDirect points out:

The more melanin, the darker the eyes, and the less melanin, the lighter they are. Melanocytes, the cells responsible for producing melanin, are not yet fully formed when a baby is born, hence this possible variation.

Okay, but what's that got to do with the sky and clouds? We'll get to that.

Read more:Here's Why Green-Eyed People Are Rare and Special

Clouds and grey eyes

According to Dr. Karan Rajan, people have grey eyes for the same reason that... the sky is gray. In a video posted on TikTok, the doctor explains:

The iris has a layer of cells called stroma, like people with blue eyes, those with gray eyes have almost no melanin in their iris stroma. In blue eyes, the shortest wavelength, blue, is the most diffused, giving the eye a bluish tint.

It's for similar reasons that the sky is blue. The doctor continues:

The difference between gray eyes and blue eyes is that gray eyes have more collagen deposits in the stroma. This means there is more scattering of light wavelengths (...) Similarly, in gray clouds, light passes through raindrops, which scatters wavelengths equally... making gray or white clouds appear.

Read more:This woman's eye infection turned out to be something worse: 'I could see them moving across my eye'

This article has been translated from Gentside FR.