Structure And Working Of Human Eye Pdf

structure and working of human eye pdf

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The day aims to focus attention worldwide on blindness and vision impairment. The Human eye works on the refraction of light through a natural convex lens made up of transparent living material and enables us to see things around us. And the ability to see is called vision, eyesight, or drishti. The human eye consists of the cornea, iris, pupil, ciliary muscles, eye lens, retina, and optical nerve.

How your eyes work

Question 1 What is night blindness? What causes night blindness? Question 2 How does eye adjust itself to deal with light of varying intensity? Question 3 Why we cannot see our surrounding clearly when we enter a darkened cinema hall from bright sunshine but our vision improves after some time?

Question 4 How does the eye lens differ form the ordinary convex lens made of glass? Question 5 What are rods and cones in the retina of our eye? Question 6 What is myopia? How is it caused and corrected? Question 8 What is cataract? How can the vision of a person having cataract be restored? Question 9 What is meant by persistence of vision? Question 10 How you can take care of your eyes? Question 11 Name few food items which contain Vitamin A? Question 12 What is blind spot in the eye? Question 13 What is the function of retina, iris, ciliary muscles, eye-lens, cornea?

Question 14 What is the range of vision of normal human eye? The outer coat of the eye is white. The iris is actually that part of the eye which gives the eye its distinctive colour. The eye-lens focusses the image of an object on the retina.

More light then enters our eye and we can see clearly. Less light then enters our eye and we can see clearly. The retina of our eye has a large number of light-sensitive cells. Rods are the most important for vision in dim light as during the night. This is called blind spot. Thus, the image formed on the retina of the eye does not fade away immediately.

The far point of a normal human eye is at infinity. Myopia is caused either due to high converging power of eye-lens or due to eye-ball being too long. The image of distant object is then formed on the retina and hence can be seen clearly. Cataract decreases the vision of the eye gradually. So, we should never look directly at the sun or other powerful lights.

Do not read by bringing the book too close to your eyes or by keeping it too far from the eyes. The inability of eyes to see properly in dim light especially at night is called night blindness.

Such persons develop their other senses more sharply. The braille was developed by Louis Braille who was himself a visually challenged person. There is a braille code for common languages, mathematics and scientific notations. University and has many years of experience in teaching. It gave me all the information what I was searching through? And thanks alot keep doing mam!

Your email address will not be published. Comments Your work is fantastic. Really useful and helped me a lot…. Thank you for helping us!!!!!! Leave a Reply Cancel reply Your email address will not be published.

STRUCTURE OF HUMAN EYE AND ITS WORKING AND DEFECTS IN HUMAN EYE

Question 1 What is night blindness? What causes night blindness? Question 2 How does eye adjust itself to deal with light of varying intensity? Question 3 Why we cannot see our surrounding clearly when we enter a darkened cinema hall from bright sunshine but our vision improves after some time? Question 4 How does the eye lens differ form the ordinary convex lens made of glass? Question 5 What are rods and cones in the retina of our eye? Question 6 What is myopia?

Human eye , in humans, specialized sense organ capable of receiving visual images, which are then carried to the brain. The eye is protected from mechanical injury by being enclosed in a socket, or orbit, which is made up of portions of several of the bones of the skull to form a four-sided pyramid, the apex of which points back into the head. Thus, the floor of the orbit is made up of parts of the maxilla, zygomatic, and palatine bones, while the roof is made up of the orbital plate of the frontal bone and, behind this, by the lesser wing of the sphenoid. The optic foramen , the opening through which the optic nerve runs back into the brain and the large ophthalmic artery enters the orbit, is at the nasal side of the apex; the superior orbital fissure is a larger hole through which pass large veins and nerves. These nerves may carry nonvisual sensory messages—e. There are other fissures and canals transmitting nerves and blood vessels.

Eyes are organs of the visual system. They provide animals with vision , the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and convert it into electro-chemical impulses in neurons. In higher organisms, the eye is a complex optical system which collects light from the surrounding environment, regulates its intensity through a diaphragm , focuses it through an adjustable assembly of lenses to form an image , converts this image into a set of electrical signals, and transmits these signals to the brain through complex neural pathways that connect the eye via the optic nerve to the visual cortex and other areas of the brain. The most simple eyes, pit eyes, are eye-spots which may be set into a pit to reduce the angles of light that enters and affects the eye-spot, to allow the organism to deduce the angle of incoming light. Complex eyes can distinguish shapes and colours. The visual fields of many organisms, especially predators, involve large areas of binocular vision to improve depth perception.


Three layers of human eye​​ Cornea further extends with a membranous structure called conjunctiva. The connecting area of cornea and conjunctiva is limbus. External fibrous coat is formed of cornea and sclera. This coat is formed by the iris, ciliary body and choroid (anterior to posterior).


The Human Eye: Anatomy, Structure, Working, Function and Defects

The human eye has been called the most complex organ in our body. It is amazing that so small can have so many parts. Eye is a natural optical instrument.

Members of the animal kingdom use different strategies to detect light and focus it to form images. Human eyes are "camera-type eyes," which means they work like camera lenses focusing light onto film. The cornea and lens of the eye are analogous to the camera lens, while the retina of the eye is like the film. To understand how the eye sees, it helps to know the eye structures and functions:. The coating on the interior back of the eye is called the retina.

Structure and Function of the Human Eye

Special cells called cones and rods are located in the retina. These cells are known as photoreceptors and help absorb light. The majority of the cones are located in the macula, or central area, of the retina. Cone cells help us see colour and detail. Similarly, the macula allows us to read and clearly recognize people's facial details, such as eye colour and whether they have freckles.

The structures and functions of the eyes are complex. Each eye constantly adjusts the amount of light it lets in, focuses on objects near and far, and produces continuous images that are instantly transmitted to the brain. The orbit is the bony cavity that contains the eyeball, muscles, nerves, and blood vessels, as well as the structures that produce and drain tears.


Each muscle coordinates with a muscle in the opposite eye. This allows for parallel movement of the eyes and thus the binocular vision characteristic of humans.


Eye anatomy and function

"what you seek,is what you get"

The open eye features the pupil, the black centre, the iris, the coloured ring surrounding the pupil, and the sclera, the white of the eye. The caruncle is tucked into the inner corner of the eye, while the upper and lower eyelids lubricate and protect. Our vision allows us to be aware of our surroundings. Eighty per cent of everything we learn is through our sight. Your eye works in a similar way to a camera. When you look at an object, light reflected from the object enters the eyes through the pupil and is focused through the optical components within the eye. The front of the eye is made of the cornea, iris, pupil and lens, and focuses the image onto the retina.

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