The human eye, layer, Segments and Different part

Human eye

The human eye is the most important sensory organ in our body that allows us to vision. shape of eyeball is not a sphere but an oblate spheroid, generally it’s referred to a globe And the eyeball is made up of three layers. The outer layer is fibrous layer. Middle layer of the eye is known as vascular layer and the innermost layer is called nervous coat.

The fibrous layer

It is The outer most layer of eyeball

it is the outer white fibrous wall of the of the eyeball, that is protect the whole eyeball

fibrous layer of the eye contain cornea and sclera

The middle layer (vascular coat)

it is a pigmented vascular layer of the eyeball between the retina and the sclera.

it is supply nutrients to the various structure of the eyeball.

it is consist of three parts, which are iris, ciliary body, and coroid

The nervous layer

It is inner most coat of the eyeball, also known as retina, retina having large number of the light sensitive cells

It’s a complex tissue that performs the visual functions

The light sensitive cells absorbs light and sends sensory information to the brain through the visual pathway

The light sensitive cells (or the photoreceptor cells) are two types for the vision,The rods and cones


The roads cells are response to the intensity of light.

These cells are responsible for the size, shape, and brightness of visual images


the cons cells are respond to the color of the objects, and function best in relatively bright

these cell more actively function in relatively bright

Different part of an eye



it is The front bulging part of the eyeball

it is the transparent layer forming the front portion of the eye

The cornea allows light to enter the eye for vision.

it is convex in shape and bulges outside

 the Iris

it is the thin and dark coloured muscular diaphragm located just behind the cornea

it regulate the amount of light that entering the eye by controlling the diameter and size of the pupil


it is it the small circular opening or hall located in the middle of iris of the eye, and it is appear black

It is a contractile structure; Size of the pupil gets wider or narrower depending upon the intensity of light entering in the eye.


Crystalline lens.

The Eye lens is made up of transparent jelly like substance, which is made up of proteins.

it is healed by the Ciliary muscle and suspensory ligament, it’s focuses light and allows you to see

The suspensory ligament adjust the focal length of the eye so that we can see distancetant and nearby object  clearly.

ciliary muscle

The ciliary muscle is consists of circular smooth muscle fibers

the ciliary muscle helps in the changing the curvature and focal lenth of the eye lence

that controls accommodation for viewing objects at varying distances

The Space between the lance and the cornea filled with a colorless fluid known as


Aqueous Humor

it is a viscous transparent fluid filled in the area between the cornea and eye lens

Aqueous Humor is secreted from the ciliary epithelium, into the posterior chamber

it Maintains the intraocular pressure and prevent the eyeball from collapsing due to the change in atmospheric pressure


 Vitreous humor

it is the highly transparent, colorless, jelly like substance field in the space between the retina and eye lance

it’s most of part made up of water and the rest is solid,

it’s Most importantly function is the maintaining the shape of the eyeball

The pressure of the vitreous humor also helps to keep the retina in place.


it is an oval-shaped yellow pigmented spot near the center of the retina which is response to clear sharp vision


The fovea is perhaps the most important part of the eye

it’s contains the largest concentration of cone cells.

It is cells takes the picture that is sent to the brain through the optic nerve fiber, and give rise to the sensation of vision

Blind spot

it is the small region in the retina where the optic nerve enter in the eye

It is do not have photoreceptor cells, so it is insensitive to light. That’s why it is called the blind spot.

Segments of eyeball

Posterior segment

Vitreous humors, retina, choroid, optic disc

Anterior segment

Crystalline lens, iris, cornea, anterior chambers,  and posterior chambers

Anterior chambers of anterior segment are the

The anterior chamber is between Anteriorly – back of cornea

and Posteriorly is situated  – iris and part of Ciliary body

it is 2.5 mm deep chamber

Posterior chambers

The posterior chamber situated in the middle between the lance and back of the iris

It’s Anteriorly – posterior surface of iris

and Posteriorly is – crystalline lens and its zonules

and it is Laterally – Ciliary body are situated


Author: Dr. vivek saini

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