Eye | Definition, Synonyms, Antonyms & Etymology


Eye is the sensory part of the human body. It allows you to see. Eyes capture visible light from the world around you and turn it into a shape your brain uses to form your sense of vision because the brain does not have its sensory abilities. Its major function is to inform the form, dimension, shade, and the texture of any object.

Definition of Eye

It is an organ of vision that receives light and visual images or it is an organ responsible for visualization.

Etymology of Eye

The word eye originated from Old English eage of Germanic origin related to Dutch oog and German Auge.

Structure of Eye

Human has 2 eyes and is positioned on the left and right side of the face. The eyes sit in the bony cavities known as the orbits. There are 6 extra-ocular muscles in the eyes that manage the movements of the eyes.

Its front observable part is made up of the white color sclera, a colored iris, and the pupil. A thin layer of the eye is known as the conjunctiva glands. The form of the eye is approximately spherical.

Eyes have an anterior or front part comprised of the cornea, iris, and lens. The cornea is a clear and curved part of the eye. Also, it has the back part associated with the posterior section composed of the vitreous, retina, choroid and the external white shell called the sclera.

Tunic of Eyes

The tunics in the eyes inwardly lessen in size as they become more specialized and internally, it contains the lens and the aqueous and vitreous humors. Eye has 3 tunics from the outside surface of the eye inward which are known as:

Fibrous tunic: This tunic consists of Cornea and Sclera.

Vascular tunic: It is composed of the Iris, Ciliary Body, and Choroid.

Nervous tunic: This inner tunic consists of a retina.

Parts of the Eyes and Their Functions

Cornea: It is the crystal clear part of the eye. It covers the iris and pupil. The cornea permits the light to enter the inside of the eye.

Iris: This is the color part. It controls the size of the pupil. It manages the quantity of light entering the eye.

Pupil: It is the black opening in the center of the colored part of the iris.

Sclera: It sustains the shape of the eyeball. Also, it protects the eyes.

Retina: It is a layer of the photoreceptors and glial cells in the eyes.

Ciliary Body: It makes the fluid in the eyes. Also, it comprises the ciliary muscles which adjust the shapes of the lens.

Choroid: It is also recognized as choroidea or choroid coat. It is the vascular layer of the eye.

Lacrimal Glands: It is also identified as a tear gland. This gland produces tears which help the eyes when they become dry. Also, it clears away the particles which bother the eyes.

Lens: It is the crystal clear structure in front of the eye at the back of the pupil.

Vitreous Humor: It is a clear, neutral, and jellylike liquid. It fills the space between the lens and the retina.

Aqueous Humor: It is a clear water-like fluid like the blood plasma. It contains low protein concentrations.

Optic Nerve: It is also identified as the cranial nerve. It consists of over 1 million nerve fibers. This sends visual messages to the brain to help you to see.


Its size differs between adults by 1mm or 2mm only. The eyeball is usually less high than it is wide. The height of a human mature eye is about 23.7 mm, the width is 24.2mm, and the size or depth averages from 22.0 to 24.8 mm with no major difference among sexes and age groups.

Uses of Eyes

There are many uses of eyes which some of which are given below:

  • Sense of Sight
  • Improves Brain Focus
  • Storage and Transference of Information
  • To understand the surroundings
  • Keeping Balance
  • Maintaining circadian rhythm
  • To visualize objects

Eye Conditions and Diseases

  • Age-Related Macular Degeneration
  • Amblyopia
  • Astigmatism
  • Cataracts
  • Color Blindness
  • Diabetic Retinopathy
  • Dry Eye
  • Floaters
  • Glaucoma
  • Pink Eye
  • Retinal Detachment

Similar Words

  • Loop
  • Hoop
  • Circle
  • Ring
  • Round
  • Belt
  • Band


  • Organ of sight
  • Eyeball
  • Peeper
  • Orb
  • Optic
  • Globe
  • Visibility
  • Range of vision
  • Observation

Antonym of Eyes

  • Disregard
  • Neglect
  • Aloofness
  • Disinterest
  • Indifference
  • Unconcern


  • My cat is blind in one eye.
  • Her eyes are very beautiful.
  • He opened his eyes at night.
  • Sara’s eyes filled with tears.
  • The color of the eyes of the Ali is green.

FAQs (Frequently Asked Questions)

Which are the parts that the human eye consists of?

  • Sclera
  • Cornea
  • Iris
  • Pupil
  • Lens
  • Retina
  • Optic Nerves

Mention the name of some sensory organs.

  • Eyes
  • Ears
  • Nose
  • Tongue
  • Skin

Mention the types of optic nerves.

It is of two types which are:

  • Cones
  • Rods

Mention the name of the most significant part of the eye.

The cornea is the most significant part.

Tell us the average weight of the human eye.

The weight of the human eye is nearly about 7.5 grams.

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