The human eye has been made of different intricate parts that work together to make a person, able for seeing or having vision. The visual activity of an eye is generally defined by the clarity of the image that has been seen by the human eye. Focussing on such concepts, this present tutorial will define the structure and the functioning of an eye including the activity of the lens of a human eye.
Sclera − The outer white layer of the eye that can be easily visible as it is situated at the outer layer of the eye is usually known as the sclera.
Cornea − The front part of the sclera that is transparent in nature is called the cornea. This part of the eye helps to enter the light into the eye.
Iris − The structure of this part is like a ring and identified behind the cornea is called Iris. This part of the eye is found to be a dark muscular tissue which is responsible for the determination of the colour of one’s eye (Alipour et al. 2022). This internal part of the eye helps in regulating or adjusting the exposure to light.
Pupil − The small opening identified in the iris part of the eye is called the pupil. The amount of light that enters the eye is controlled by this particular part of the human eye.
Lens − the name lens knows the transparent structure identified and placed behind the pupil. Muscles named ciliary control the shape of this internal part of the eye. The reason for changing shape is to help the retina to create focus on the object the eye is visualising. In order to create focus on the object situated at a distance away, it becomes thinner, and it becomes thicker to focus on nearby objects.
Retina − This part is identified as an internal part of the eye that is highly photonsensitive. Numerous nerve cells that help the conversion of the image that an eye senses into an electrical impulse develop the construction of this layer. This impulse is then transmitted to the brain with the help of optic nerves.
The optical nerves are considered a crucial internal part of an eye which is basically a bundle of one million nerve fibres. These nerve fibres help in carrying visual messages to the brain (Aao, 2022). Two types of optical nerves are as follows:
Cones − The cells that are sensitive to bright light are called cones which help in getting coloured vision.
Rods − This is considered a type of optic nerve cell that is sensitive to dim-light. In order to get the vision that is peripheral, these optical nerves are considered o be responsible.
The working process of a human eye often shares a similarity to the work process of a camera. The functioning of an eye is described in the below section:
The light gets into the internal parts of an eye through the help of a cornea that acts similar to the lens of a camera. The iris controls the amount of light required to get in and such action takes place by controlling the size of the pupil. The action of such parts is similar to the work process of the diaphragm of the camera. Sharing similarities to the work process of an autofocus lens of the camera, the lens helps to create focus on an object (Optimax, 2022). In order to focus, the refraction of light happens differently in different parts as the cornea has 1.376 refraction and for the lens, the value is 1.42.
The lens is located behind the internal parts such as the iris and pupil that are considered transparent flexible tissue. This part is able to provide 25-35 % focusing power to the eye. This part is carved in shape and has an elasticity that offers a flexible nature to this part. This aspect helps to become oval-shaped and elongated for creating focal points for near objects and for objects situated far away, respectively.
The tutorial has shed light on the fact that the eye is considered a crucial human organ that helps one to visualise things by letting the light enter or refract on the lens of the eye. The eye makes the vision of the object by reflecting the image of the object in a specific part of the human brain. After entering the eye through the cornea, the light passes through watery fluid and enters the lens in order to reach the lens. Making changes in thickness, the lens help to bend the light which makes possible the refraction of light, thus the vision is built.
Q.1. Does the human eye grows with age?
Ans. The eyeball grows in a rapid manner. At the time of birth, the size of an eyeball remains 16- 17 millimetres. By the age of 12 years, a human eye attains its full size.
Q.2. What is the vision and its range?
Ans. The terminology of physics refers to the action of an eye to refract light by letting the light enter the eye is called vision. The range of vision of a human eye is from 25cm to infinity.
Q.3. What is eye liquid called?
Ans. The name of the eye liquid is aqueous humour. The space in front of the lens is filled with a watery and clear fluid that is generally known by the name aqueous humour.
Q.4. Why is the pupil black?
Ans. The light that enters a human eye, most of it does not escape. This is the reason why the pupil appears black in colour.
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