In this Article we read about "What does the lens of eye do". How it works and what is the main role of lens in eye. As you Read in the pervious article How Does human Eye works. 

What is Lens?

Lens is a a transparent, biconvex structure in eye, along with cornea, helps to refract light to focus on retina. The lens, by changing shape, capacities to change the distance of eye so that concentrate on items at different separations, thus allowing a sharp real image of the object protest important in the frame of retina. The adjustment of the lens is known as accommodation. Accommodation is the similar focus on one image. The lens is more flat on its anterior side as its posterior side.

What is the function of Lens?

The two principle elements of lens of eye are to focus light onto the retina and to help the eye to concentrate on the object of various distance. The lens of eye is rubbery, jelly like structure and located right behind the cornea and is held set up by ligaments that are joined to an arrangement of muscles called ciliary muscles.

The tendons and ciliary muscles help eye to focus either relaxing or pulling the lens allowing it more flexibl, spherical and flatter in shape. The adjustment of lens occurs more quickly allowing eye to focus nearby object at one moment and then the far object at the other moment.

                        Sometimes  the eye does not work appropriately or needs additional help to concentrate on items accurately.  Eyeglasses or contact lenses provide the accuracy.The lens of the eye may also become shady with age, which is the condition to know as cataract. Lens replacement surgery is available for people with cataract. The lens of eye may likewise weaken with age, and its capacity to alter from a removed to a close concentration decays and more established people require perusing glasses to right this issue.

Your Eye works like a kind of Camera. As you want to know that how human eye work lets take the example of camera you will understand. It takes picture around you and convey it to your brain. Human brain works out that what you are seeing around you and it act like a Memory. It happen just like that you open your eye in the morning and close your eyes at night while sleeping.

As you can see in the above Diagram about the comparison of camera and eye, Actually camera is discovered as a copy  to see the human eye.

How Camera Works?

Light rays from an object passes through the lens and then the camera record or capture a snap. The picture that is captured in a camera is Upside down but when we see it in the Computer and device, it was not upside down.

How your eyes work?

Your eyes work as the similar way like camera, as light passes through your eye and the image is recorded back to your eye retina. The picture that your eye takes it also upside down!
As the Question is that "why you don't see the image upside down?"
When you see the image the eye send it to your brain and your brain turns the picture to the right way and you see the things right way up. As we read in the previous article.

1.  The structure of eye: 

• Iris
• Cornes.
• Lens

Iris:  It is similar to the diaphagm of camera,your iris widens in Dim light and Narrow in bright light.Compare this to the average camera lens which may have f-number from f/2.8 to f/22. The main function of iris not to control the intensity of light coming into your eyes.

Cornea and Lens: There are two lens in your eyes, Cornea and eye lens. 

• Cornea,the front surface of eye, does more of focusing in your eye.
• Eye-Lens provide adjustable fine tunning of focus.

• This is because the cornea air surface has large change in index of refraction, so light bends alot.
• The power of eye lens is 43 Dipoter.
• As like our eye lens focus the thing we are trying to see.

So, the eye lens changes its focal length by changing its shape and it depends upon our eye muscles that contract or relax. Contract when the more bending power with shorter focal length and Relax when the less bending power with the long focal length.

       

What is Eye?

  The eye is an organ that recognizes light and sends motions along the optic nerve to the mind. In people, the eye is a valuable sense organ that gives us the capacity to see. It takes into light discernment and vision, including the capacity to separate amongst colors and depth.

                                                          Although small in size, the eye is an exceptionally complex organ. The eye is approx 1 inch wide, 1 inch deep and 0.9 inches tall.  The human eye has a 200-degree seeing angle and can see 10 million colors and shades. Human have two eyes which allow us to have better deep recognition and Binocular stereopsis.

Parts of Eye | Anatomy of eye.

• Cornea -  It is a transform layer in front of eye that cover iris,puple and anterior chamber.
•  Iris -    It is the thin,circular structure in eye and pigment tisuue controls pupil constriction and pupil shutter and it is colored part of eye.
• Pupil -   It is the hole in the middle of the Iris by which light passes through retina. Pupil is black and light is absored by this by which we are able to see things. 
• Sclera -   It is the white part of the eye that is covered around the globe of height and it is continuous with cornea.

• Anterior Chamber - A fluid filled chamber between Iris and Cornea's inner surface composed to endothelium. 
• Trabecular meshwork - Meshwork tissue located around the around base of Cornea and keep the eye in angle.Trabecular meshwork is continuous with the ciliary body.
• Crystalline Lens - The Crystalline lens conveys 1/3 of the refracting or focusing power to the eye. It is a stringy tissue that can change shape to increase or decrease it's power because it can change shape and it allows eye to move around and to focus on objects.
• Ciliary body - It is the muscle that contract to change the shape of lens. It allow human to focus the near object and the other function of ciliary body is to produce aqueous humour that flow into the interior chamber.
• Retina - Retina is a light sensitive tissue that capture light and transfer it to the brain as nerve impulse.
• Optic nerve - It is the network of nerve cells which receives impluses from nerve fiber layer on retina. It transfers nerve impulse to the brain.