Focus on vision - by Essilor

80% of all the information we receive is perceived by our eyes.

The eye is a fragile organ which must be treated with care. Understanding how vision works allows you to take better care of your visual health.

Below you will find some useful information to enhance your knowledge about the phenomenon of vision.


How does vision work?

The optical system that enables visual perception is very complex, since it involves a series of elements which are all required to produce vision.

• 1. The eye intercepts light.

• 2. An image of the external world is created on the retina.

• 3. The nervous system transmits this image to the brain.

• 4. The brain interprets the information received to form an image.

The crystalline lens: the essential organ

The crystalline lens is the organ which focuses. It plays an essential role in vision. This lens contracts and expands to focus rays of light on the retina.
Like an autofocus camera lens, it helps to adjust images in accordance with the distance of the external object, a function that is called accommodation.
When the eye presents no visual disorder, images of near or far objects are formed on the retina through accommodation. The crystalline lens bulges in or out according to its distance from the object in order to create a focused image.
Vision problems

Vision is blurred or deformed when the image of the object does not form on the retina.
This type of visual disorder is called ametropia. Myopia, hyperopia and astigmatism are the three kinds of ametropia.

Presbyopia affects all of us after the age of 40: This is not a visual defect but a natural change in eyesight. It results from the natural ageing of the crystalline lens and is characterized by the eye's gradual loss of the ability to focus ("accommodate"). Presbyopia develops in addition to vision problems such as myopia, hyperopia and astigmatism.