The structure of the eye has always been a fascinating topic to discuss. Apart from all the romantic lines, you heard about the eyes and its colour, which makes them fascinating is their small detail structure. The eye is a small yet very important part of the body let us visualise the beauty of this world. In this modern era, our eyes are under various kinds of threats of digital rays hence acknowledgement of their structure and function helps to comprehend it efficiently. Do you ever wonder what light does to our eyes to let us see any object clearly? If not, then we are here to discuss the complete detail of the structure of the eye and their functions that help you to understand it better.
How does the Structure of the eye work?
Though the structure of the eyeball looks like a sphere, it is not exactly a sphere. The structure of the eye consists of two units called the anterior segment and the posterior segment.
Cornea, lens and iris make up the anterior segment while the cornea being a transparent and curved part also forms a part of the posterior segment.
The posterior segment is the back portion or two-third portion of the eye that is composed of the anterior hyaloid membrane and optical structures like vitreous humour, optic nerve, retina and choroid.
Iris is the pigmented circular part of the eye that is in the centre of the eye.
The black coloured looking structure is a pupil that predominantly controls the number of light rays entering in our eyes with the help of iris dilator and sphincter muscles.
The light rays enter the eye through the cornea and then pupil and then through the lens.
The lens changes shape for the accommodation which is controlled by the ciliary muscles.
When the light rays hit the retina, the light-sensitive cells called photoreceptor cones and rods convert it into electrical signals.
The electrical signals are then transmitted to the brain by the optic nerve hence our brain interprets it as a sight to behold.
Dive into the quick guide to the structure of eyes and the function:
Vitreous Body - The word vitreous is derived from the term vitreus in Latin meaning “glasses-like”. The vitreous body is a clear gel or glass-like gel that fills the gap between the lens and retina. It is also known as vitreous humour or the vitreous.
Function: The function of the vitreous is mainly to protect the eye. And most importantly, the fluid supports and holds the eyeball spherical shape.
Cornea - It is a transparent part of the eye present at the very front that covers other parts like the iris, pupil, and anterior chamber. It is the primary structure to offer light direction in the eye.
Function:The cornea is present at the outermost part of the eyes. The main function of the cornea is to regulate and focus the entry of the light rays. The excess and lesser amount of light are decided by the cornea by either bending or reflecting the incoming light into the lens.
Iris - It is a thin and circular structure composed of two different layers called fibrovascular layers also known as stroma and a pigmented epithelial cell beneath the other.
Function: Iris is mainly responsible for controlling the size and diameter of the pupil. By regulating the aperture of the pupil, it ultimately helps in the number of light rays entering the retina. Our eye colour is also defined by the iris.
Pupil - It is a hole in black colour located in the centre of the eye. It is responsible for regulating the amount of light in the eyes and then focusing it on the retina.
Function: The pupil of the eyes allows light rays to enter the eye and then focuses it on the retina to start the process of vision.
Ciliary Muscle/Body - It is a ring of smooth muscles that is present above the lens and produces aqueous humour.
Function: The ciliary muscle controls the accommodation of objects at different distances. It does so by replacing or tightening the zonules to make the lens change shape for focusing. The zonules hold the lens in the eye that controls the position of the lens to change its shape for accommodation.
Lens - The crystalline structure of the eye lens is a transparent structure present behind the iris that, along with the retina, helps to focus light on the retina.
Function - The lens changes its shape to change the focal distance of the eye. In simple words, the lenses focus the light rays onto the retina to form clear objects at any distance.
Anterior Chamber - It is an aqueous humour-filled space inside the eye lying between the iris and cornea innermost surface called the endothelium.
Conjunctiva - It is a tissue that lines the inner side of the structure of eyelids and covers the sclera.
Function - The main function of the conjunctiva is keeping the front surface of the eye moist and lubricated as well as the inner surface of the eyelids. The lubrication helps to cause easy opening and closing of the eyes without any friction or irritation. It also protects your eyes from unwanted foreign microorganisms.
Sclera - It is a tough and dense white cover over the structure of eyeball along with the cornea which forms the external coat. It is also known as the white of the eye.
Function - It is a tough and protective layer over the entire eyeball with the cornea over the front to the optic nerve. It offers protection to all the parts inside of the eyeball from foreign particles.
Retina - It is a light-sensitive tissue-lined at the back of our eye. Cornea, pupil and lens focus the light rays on the retina to form an image.
Function - The main function of the retina is to convert the light rays into electrical impulses that travel through the optic nerve straight to the brain. Where the brain interprets the message and forms the image we get to see.
Macula - It is a part of the retina at the back of the eye. It is made with majorly cone cells that are responsible for the colour, central and sharp vision.
Function - It has the highest concentration of photoreceptor cells that help to deduce light and further send the signal to the brain.
Optic Nerve - The optic nerve is the second of various cranial nerves that are responsible for bringing information from the sense organs to the brain.
Function - It connects the eye to the brain by carrying the impulses made by the retina which are sent to the brain to interpret and let us see images.
What are common eye diseases?
Apart from its beauty and magnificent structure, you’ll experience various common types of eye diseases. The most common ones are nearsightedness(myopia), farsightedness (hyperopia) and presbyopia. Other eye-related diseases which are most common are age-related macular degeneration, glaucoma, cataract and diabetic retinopathy. Other eye diseases which happen but are very rare include strabismus and amblyopia.