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The crystalline lens is the natural lens of the eye that is located in the anterior segment and is one of the most important parts of the ocular structure, since it is responsible for the images to be sharp in the retina.

Over time, like the rest of the body, the lens ages and loses its elasticity and transparency.

The lens is located behind the vitreous humor and iris, and its thickness varies throughout life.

En Área Oftalmológica Avanzada We explain, then, what is the lens of the eye. 

What is the lens of the eye?

The lens of the eye is a transparent and colorless lens whose main function is to focus images correctly. This is possible because it is flexible, biconvex, lenticular and is not irrigated by blood vessels.

The lens represents one of the most important parts of the eye.

It is in the anterior segment of the eye, behind the iris and vitreous humor.

The curvature of the crystalline lens is greater on the posterior face than on the anterior face and this forms the border between the two parts of the eye known as the anterior pole and rear pole.

As the years go by, the lens acquires new layers inside that vary in thickness.

When we are born, the lens is 3,5 mm thick, in adulthood the thickness ranges between 4,5 and 6 mm and in old age it can be up to 9,5 mm thick.

Lens functions

It performs many important functions so that we can enjoy correct vision, and many of them are possible thanks to its ability to accommodate light.

The main functions of the lens are:

  • Deflect the rays that reach inside the eye so that the images can form clearly on the retina.
  • Adapt vision at any distance, be it near, medium or far. The 20 diopters of the lens together with the 40 diopters of the cornea direct the rays towards the taint so that the objects can be seen correctly.
  • The lens of the eye works as a reference to the brain to calculate the distance at which an object is in the campor visual.

Lens diseases

The conditions associated with the lens are:


Over the years, the lens loses elasticity and its accommodative capacity begins to be deficient.

As a consequence, all human beings over the age of 40 present some type of difficulty seeing correctly up close.

La presbyopia Progress progressively. There are different types of presbyopia treatment which are proposed based on the needs of the person and the eye condition. Among the most common are glasses or lenses for the treatment of presbyopia but, the only way to correct it is definitely by presbyopia surgery


The cataract is is the opacity of the lens caused by aging and usually manifests from 65 years.

This condition can be corrected by cataract surgery in which the lens is replaced by a intraocular lens.

The procedure is simple and outpatient, and after cataract operation the person can see again clearly

En Área Oftalmológica Avanzada we are experts in the treatment and diagnosis of lens diseases. Contact us if you need more information or are interested in requesting a medical appointment. 

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The lens is one of the parts of the ocular structure that fulfills one of the most important functions. We tell you what it is and its conditions.
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Área Oftalmológica Avanzada
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