All about the eye!

The eye is the organ of vision. It receives between 70% and 80% of the information transmitted to our brain.

1/ How does the human eye function?

While the eye is perhaps the most complex organ in our body, its functioning could be compared to that of a camera. It’s our optical system which, like a photographic lens, forms an image on the retina. The nervous system then takes over to faithfully retranscribe this image and send it to the brain, which is responsible for deciphering this image.

It’s therefore the most advanced of all cameras, which every minute, every second, takes on the task of capturing, transcribing and deciphering the world around us. Focusing, automatic adjustments according to light intensity and variations, and even an integrated cleaning system... Our eye has options that even the most high-tech camera can never match. This is especially important when you're doing sports. It’s the proper functioning of your eye that will let you, even when cycling at 40km/hr, to spot an obstacle in the distance and avoid it without even realising the complex mechanism behind your eyes...

2/ The different components of the eye

THE CORNEA, THE EYE'S FIRST PROTECTION

The cornea is a transparent membrane located at the front of our eye. Considered the most fragile part of the eye, it acts as a first stage of protection. The cornea acts as a window through which light enters. This is why the cornea must remain perfectly clean thanks to our lacrimal system (our tears) and the regular blinking of our eyes.

CRYSTALLINE, THE LENS OF YOUR EYE AND THE NATURAL UV FILTER

Crystalline is the lens of the eye, and makes the adjustments necessary to distinguish objects at different distances.

To focus on near objects, the lens bulges slightly, while to focus on far objects, it becomes flat and returns to its resting position. During prolonged exposure to the sun, the lens is also put to great use as it filters out the sun's various UV rays. In kids, the development of the lens is not complete until they are 12 years old, which is why it’s important to protect the eyes of young ones with suitable sunglasses. Find out more about kids’ eyes.

THE PUPIL, THE OPENING OF THE EYE

The pupil is an opening that lets light enter the eye. The diameter of the pupil will vary according to the amount of light entering the eye.

Did you know...? If you wear sunglasses that are not 100% UV certified then your brain feels protected and so the pupil remains wide open. This is even more harmful to your eyesight as the lens and retina will be the first to be affected by the lack of protection of poor quality glasses.

THE IRIS, THE COLOUR OF YOUR EYES

The iris is the part that gives our eyes their colour and protects our retina from overexposure to light. Like a camera diaphragm, the iris regulates the opening of the pupil by contracting more or less. Remember: the idea that light eyes are more sensitive to light than dark eyes is a common misconception. It’s true that light-coloured irises contain less pigment than dark irises and therefore absorb less light. But only on the surface. Underneath the coloured pigments is a second layer that is perfectly opaque, regardless of the colour of your eyes.

THE RETINA, THE TRANSFER OF INFORMATION TO BE PRESERVED

The retina is a transparent and very thin membrane that covers the inner part of the eye, from the iris to the optic nerve. It’s through the retina that light stimuli are transformed into nerve stimuli so that they can be transmitted to the brain via the optic nerve.

3/ Sunglasses, the essential item to protect your eyes

During exposure to the sun, UV rays are absorbed by the cornea and the lens. Without the protection of 100% anti-UV sunglasses, direct UV rays or those reflected by water, sand or snow, can cause short-term irritation: your eyes start to swell, become red and may even water.

Although these effects may disappear after a few days, it’s mainly the retina and the lens that suffer from these long-term harmful effects. And this can be irreversible.

How to choose hiking glasses?

We recommend you choose a pair of sunglasses:

> 100% UV protection (CE certified)

> with polycarbonate lenses to resist impact and shocks

> the best possible coverage to keep UV rays out

Amadine - Specialist editor, eye health advice

"Remember to protect your eyes and your children's eyes when hiking. My advice: check that the lenses offer 100% UV-protection and choose polycarbonate lenses which provide high impact resistance!"