Answer:

The human eye is considered to be one of the most valuable and sensitive sense organs on the planet. It allows us to take in the beauty of the world and the colours that surround us. After closing our eyes, we can identify items to a certain extent based on their scent, taste, or the sound they make, as well as their touch. It is, on the other hand, impossible to distinguish between colours when one’s eyes are closed. As a result, the human eye is the most important of all the sense organs because it allows us to view the beautiful and colourful world that surrounds us in real time.

The human eye functions similarly to a camera. This device’s lens system projects a picture onto the retina, which is a light-sensitive screen. The cornea, a thin membrane that covers the front of the eye, allows light to enter. According to Figure 1, it causes the translucent bulge to appear on the front surface of the eyeball. The eyeball is nearly spherical in shape, having a diameter of around 2.3 cm. The pupil is approximately spherical in shape. The majority of the refraction of light rays entering the eye happens at the cornea’s outer surface, where the majority of the refraction occurs. Only the finer change of the focal length required to focus things at varying distances on the retina is provided by the crystalline lens. Behind the cornea, we can see a structure known as the iris. The pupil size is controlled by the iris, which is a black muscular diaphragm on the surface of the eye. The pupil is responsible for regulating and controlling the amount of light that enters the eye. On the retina, the eye lens creates an inverted actual image of the object, which is called an inverted real image. The retina is a fragile membrane that contains a large number of light-sensitive cells that are sensitive to light. As soon as the light is turned on, the light-sensitive cells become active and emit electrical signals. The optic nerves are responsible for transmitting these impulses to the brain. The brain analyses these impulses and, lastly, processes the information in order for us to view objects as they actually exist.

By varying the focal length of the lens, we can make our eyes focus on images from a variety of different distances. The action of the Ciliary muscle aids in the adjustment of the focal length of the lens.