Eye Diagram

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Human Eye - An Introduction

The human eye is one of the most important organs of the human body which when interacts with light gives us the sense of sight or vision. There are two kinds of cells in the eye namely rods and cones. The basic function of Rods and Cones are conscious light perception color differentiation and perception of depth. The human eye is capable of distinguishing between about 10 million colors, and it can also detect a single photo. The human eye is a part of the sensory nervous system.


Labelled Diagram of Human Eye 

The eyes of all mammals consists of a non-image-forming photosensitive ganglion within the retina which receives light, adjusts the dimensions of the pupil, regulates the availability of melatonin hormones, and also entertains the body clock.

  • The anterior chamber of the eyes is the space between the cornea and therefore the iris and is crammed with a lubricating fluid, aqueous humor .

  • The vascular layer of the attention , referred to as the choroid contains the animal tissue .

  • The iris and therefore the choroid are connected by the membrane .

  • Fovea is a minute pit placed in the macula of the retina that helps in forming a clear vision.

  • Cornea is a dome-shaped tissue covering the front of the eye.

  • Iris is that the coloured a part of the eyes and controls the quantity of light entering the eyes by regulating the dimensions of the pupil.

  • The lens is located just behind the iris. Its function is to focus the light on the retina.

  • The optic nerve helps in transmitting the electrical signals from the retina to the brain.

  • Pupil is the opening at the centre of the iris. Its size changes with the amount of light.

  • The retina lines contain several photoreceptors.

  • Vitreous humour is the fluid present within the centre of the attention and provides form and shape to the eyes.


Operation of an Human Eye

The operation of a human eye can be compared to that of a digital camera because of the following reasons -

  • Light focuses mainly on the cornea, which acts sort of like an optical lens .

  • The iris controls the light that reaches by adjusting the dimensions of the pupil, and thus it functions just like the diaphragm of a camera.

  • The lens of the attention is found behind the pupil, and it focuses light. This lens helps the attention to automatically specialise in near and distant objects, and also the approaching objects, like an autofocus optical lens .

  • The cornea and lens focus light to succeed in the retina, which may be a light-sensitive zone present on the inner lining of the rear of the attention .

  • The retina converts optical phenomenon images into electronic signals, and thus it acts as a bitmap sensor of a camera . These electric signals are then transmitted by the nervus opticus to the visual area , which is liable for the sense of sight.

Function of the Human Eye

Human eyes are a specialized sense organ capable of receiving visual images and producing the sense of sight in us. The eye receives direct oxygen through the aqueous humour. The aqueous humour nourishes the cornea, lens, and therefore the iris, by carrying nutrients, removing wastes materials excreted by the lens, and maintaining the form and structure of the eyes. The aqueous humour is liable for providing shape to the eyes. It must be clear to function properly.


Function of Lens in the Human Eye

The lens may be a transparent flexible tissue located directly behind the iris and therefore the pupil. To focus light and images on the retina becomes the basic function of the lens. The cornea and the lens are responsible for focusing the image in the retina.


Due to the elastic & flexibility the lens has, it can change its curved shape to focus on nearby or distant objects as per the requirements. The lens provides around 25-35 you look after the entire focusing power of the eyes.


The lens is attached to the ciliary muscles, which contracts and releases in order to change the shape of the lens and also its curvature.

FAQ (Frequently Asked Questions)

1. What are the external structures of the eye?

The external structures of the eye include:

  • Sclera

  • Conjunctiva

  • Cornea

  • Iris

  • Pupil

2. What is the function of conjunctiva?

Conjunctiva lubricates the front surface of the eye. It also protects the eyes from debris, dust and infection-causing microorganisms.

3. What is the function of the iris? How many layers does it have?

The iris regulates the amount of light entering the eyes by controlling the diameter and size of the pupil.

The iris consists of two layers:

  • Stroma, the front pigmented fibrovascular layer

  • Pigmented epithelial cells.

4. What are the internal components of the eye?

The internal components of the eye include:

  • Lens

  • Retina

  • Aqueous humour

  • Optic nerve

  • Vitreous humour