Anatomy of Eye

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Medically Reviewed by Dr. Aman Priya Khanna
Written by Hexahealth Care Team, last updated on 24 November 2023
Anatomy of Eye

The eyes are one of the vital sense organs of the human body. They absorb light from the environment and process it into nerve signals. The optic nerve transfers the nerve signals to the brain and translates them into the image. The eyeball is approximately one inch in size and enclosed in the pads of fat and skin. It is present in the cavity of the skull.

The major components that make up the eye are:- 

  1. Cornea
  2. Iris
  3. Pupil
  4. Lens
  5. Retina
  6. Macula
  7. Optic nerve
  8. Choroid
  9. Vitreous

Anatomy of the Eye

The components of the eye have three kinds of tissue. These tissues are based on their function in the eye: 

  1. Refracting tissues:  
    1. Refracting tissues consist of parts like the pupil, iris, ciliary muscle, cornea, aqueous, and vitreous fluid.  
    2. These tissues focus the incoming light on the light-sensitive tissue. It results in the formation of a clear and sharp image. 
    3. The vision can be unclear if the refracting tissue components get damaged or distorted. 
  2. Light sensitive tissues:  
    1. It is also known as the retina. 
    2. The retina is the deepest layer of the eye that consists of more than 120 million light-sensitive photoreceptor cells.  
    3. These cells detect light and process it into electrical signals. 
  3. Support tissues:  
    1. Support tissue of the eye includes the sclera, conjunctiva and choroid.

Components of the Eyes

Cornea

  1. The cornea is a clear, dome-shaped outermost membrane of the eye. 
  2. The pupil, iris, and anterior chamber are covered by the cornea. 
  3. It is accountable for the focusing potential of the eyes. However, it does not adjust to varying lengths as it has a predetermined focus. 
  4. The cornea is covered in nerve endings and is extremely sensitive. It is also the first line of defence against foreign objects and harm. 
  5. The cornea lacks blood vessels because it must remain clean to refract light. 

Sclera

  1. The sclera is the section of the eye that is frequently referred to as the "white of the eye." 
  2. It is a fibrous layer with a transparent cornea and forms the eyeball's supportive wall. 

Iris

  1. It is the coloured region of the eye, 
  2. The function of this muscle is to alter the size of the pupil to manage the proportion of light entering the retina. 

Pupil

  1. It is the dark area present in the centre region of the iris.  
  2. The pupil responds to light by expanding and contracting, much like the aperture on a camera. 
  3. Its role is to protect the delicate retina from harm. 
  4. The pupil can dilate or spread up to 10 mm in diameter when it is dark. The eye dilates to take in as much light as possible. 

Ciliary Muscles 

  1. The ciliary muscle is an intrinsic eye muscle that is developed as a ring of smooth muscle in the central layer of the eye, called the uvea (vascular layer).  
  2. It regulates the flow of aqueous humour into Schlemm's canal and governs accommodation for viewing objects at different distances. 

Lens 

  1. After passing through the pupil, light passes through the lens, which is a transparent convex structure. 
  2. The lens assists the eye by correctly focusing the light onto the retina. 
  3. The lens stiffens and gets less flexible as it ages, making focusing very challenging. 

Conjunctiva 

  1. It forms the lining inside the eyelids and surrounds the sclera. 
  2. The most significant functions of the conjunctiva are: 
    1. Protection and lubrication of the eye by producing mucus and tears. 
    2. Protection from microbial invasion 
    3. Immune surveillance  

Retina 

  1. It is the innermost component of the eye. 
  2. Its role is to sense the light and send it to the brain via the optic nerve. 
  3. The retina detects light with the help of millions of photoreceptor cells present in the eye. The two major cells which are responsible for transferring the electrical signal to the brain are known as rods and cones. 

Cones

  1. These cells are predominantly present in the fovea, i.e., the centre of the macula region. 
  2. They are responsible for precise colour vision. 
  3. In normal light conditions, they enable us to view and distinguish among colours. 
  4. The three types of cones present in the eye are- short or blue, middle or green, and long or red.  

Rods

  1. These cells are predominantly present around the edges of the retina. 
  2. In low light conditions, these excessively sensitive cells detect even the lowest amount of light and enable us to view. 
  3. However, rod cells cannot distinguish colours. 

Macula 

  1. The centre portion of the retina is referred to as the macula. It provides a sharp and clear vision. 
  2. The centre of the macula is known as the fovea, which consists of photoreceptor cells. 
  3. Due to the presence of cone cells in the fovea region, it is responsible for most of our colour vision and all of the central vision. 
  4. It is an essential component as damaging the macula could often lead to poor vision, deformity of images and other visual impairments. 

Optic Nerve 

  1. These are dense bundles of nerve fibres that consist of approximately 1 million tiny, retinal fibres known as ganglion cells. 
  2. It is responsible for transferring electrical signals from the retina to the brain. The transferring process is aided by the ganglion cells present in the nerves. 
  3. The optic disc is the region where the ganglion cells depart the eye. It is also known as the blind spot because there aren't any rods or cones. 
  4. By comparing the impulses from both eyes, the brain allows us to view them in three dimensions. 

Vitreous Humour 

  1. It is a translucent, jelly-like liquid that fills the void amid the lens and retina of the human eye.  
  2. The function of vitreous humour is to supply metabolic demands of the lens, coordinate eye growth and provide support to the retina. 

Aqueous Humour 

  1. It is a clear, watery liquid present between the cornea and front of the vitreous humour. 
  2. It is responsible for maintaining pressure in the eye and nourishing the lens. 
  3. As both the cornea and the lens lack blood supply, the aqueous humour carries the nutrients to these components.

Conclusion:

The eyes are among the vital sense organs of the body that enables us to see. The eye consists of various components and each of them has a specific function. It is important to take care of your eyes by taking precautions and indulging in healthy habits. You can opt for small habits like decreasing screen time and careful use of contacts to keep your eyes healthy.

Hexahealth is the first step towards the right treatment and care. We help you to connect with the top doctors and surgeons from the most trusted hospitals at affordable prices to make your healing and recovery process as relaxing as possible. From our nationwide network, we offer you the greatest and most suitable healthcare and surgical guide for the proper treatment. You are just a phone call away from the correct health care service that you require.

 

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Updated on : 24 November 2023

Reviewer

Dr. Aman Priya Khanna

Dr. Aman Priya Khanna

MBBS, DNB General Surgery, Fellowship in Minimal Access Surgery, FIAGES

12 Years Experience

Dr Aman Priya Khanna is a well-known General Surgeon, Proctologist and Bariatric Surgeon currently associated with HealthFort Clinic, Health First Multispecialty Clinic in Delhi. He has 12 years of experience in General Surgery and worke...View More

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HexaHealth Care Team

HexaHealth Care Team brings you medical content covering many important conditions, procedures falling under different medical specialities. The content published is thoroughly reviewed by our panel of qualified doctors for its accuracy and relevance.

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