The functioning of the vision

Vision begins with the entry of rays into the eye from a light-source through the cornea, the first transparent tissue. Then, the rays pass through the pupil whose size varies according to the quantity of light that enters the eye. The rays pass then through the crystalline lens, which, by modifying its form, focuses the luminous rays. Finally, the light reaches the retina and its energy creates a nerve impulse that travels via the optic nerve to the brain, which interprets it into vision.

Hypermetropia

The image is not projected exactly on the retina but behind which results in blurred near vision.

Presbyopia

With time, the crystalline lens loses its elasticity and its capacity to focus the images perceived which results in blurred near vision when reading.

Myopia

The image is not projected exactly on the retina but in front, which results in blurred distant vision.

Astigmatism

This is a visual problem created by a defect of the curvature of the cornea and/or crystalline lens and results in images being distorted at all the distances.