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In our previous anatomy and physiology session we have discussed about Lung Anatomy, Function and Disease, Anatomy of Kidney, Functions of Kidney, Anatomy of Liver, Functions of Liver, Anatomy of brain, Gait Cycle. Please check out for the link below.

Functions of Kidney

Lung Anatomy, Function and Disease

Anatomy of Kidney

Anatomy of Liver

Functions of Liver

Anatomy of the Brain

Gait Cycle

Being a healthcare professional, it is very important to have knowledge about human eye.

In today’s topic we are going to discuss about anatomy of the eye.

Let's get into the topic.

ANATOMY OF THE EYE

The eyes are the organs of sight. The eyes are about an inch in size. The eyes are complex organs which are made up of many parts. The anatomy of eyes includes cornea, pupil, iris, sclera, conjunctiva, lens, retina, optic nerve, macula, choroid and vitreous body.

Let’s discuss in detail about each part of the eye.

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CORNEA

The cornea is the front window of the eye. A clear dome over the iris. The cornea transmits and focuses the light into the eye.

IRIS

The iris is the coloured part of the eye which helps to regulate the amount of light that enters into the eye. When the light is low, the iris opens up the pupil to let more light into the eye. When the light is more, the iris closes to let less amount of light into the eyes.

PUPIL

The pupil is the dark aperture present in the iris which determines how much light is let into the eyes. The pupil changes its size to alter the amount of light entering into eyes. The size becomes smaller for brighter light and larger for low light.

SCLERA

The sclera is the dense connective tissue of the eyeball which forms the white visible portion of the eyeball. The muscle that moves the eyeball are connected to sclera. The sclera is a tough covering with which the cornea forms the external protective coat of the eye. The sclera continues with the stroma layer of the cornea. The thickness of the sclera ranges from about 0.3mm to 1.0mm

CONJUNCTIVA

The conjunctiva is a clear, thin membrane which covers a part of front surface of the eye and inner surface of the eyelids. The main function of the conjunctiva is to keep the front surface of the eye moist and lubricated. The conjunctiva has two segments, bulbar conjunctiva and palpebral conjunctiva.

The bulbar conjunctiva covers the anterior part of sclera. It stops at the junction between sclera and cornea. It does not cover cornea.

The palpebral conjunctiva covers the inner surface of both upper and lower eyelids.

LENS

The lens in the eye is used to focus the light onto the retina. The lens is a transparent structure located directly behind the pupil. The lens which is enclosed in a thin transparent capsule helps in automatic focus of near and approaching objects through a process called accommodation. It acts as an autofocus camera lens.

The Cataract is a problem when lens become cloudy which can be corrected by replacing cloudy lens with artificial plastic lens.

RETINA

The retina is a light sensitive nerve layer which makes the inner lining located on the back of the eyeball. The retina converts optical images into electronic signals. The retina has two types of photoreceptor cells, the rods and cones.

The rods react well in low light providing black and white vision. The human eye contains about 125 million rods. The cones react in medium and bright light providing central and colour vision. There are about 6 to 7 million cones in the eye.

OPTIC NERVE

The retina sends light as electrical signals through the optic nerve to the brain. The optic nerve is made up of millions of nerve fibres which transmit these impulses to the brain.

MACULA

The macula is the central part of retina which contains the special light sensitive cells. These light sensitive cells allow us to see the finer details clearly in the centre of visual field.