Eye Anatomy

Before moving on to diseases which can affect our eyes, it is better to know the basic anatomy of structures inside our eye. Although, generally referred to as a globe, the eyeball is not a perfect sphere. Each eyeball acts as a camera. It receives the light from objects and images it on back portion of the eye which then transferred to our brain for better imaging. Eyeball can be divided into two parts.


anatomy of eye



eye acts as a camera


Anterior Segment: - This include cornea, iris, aqueous humor filled two cavities and lens.


Ø Cornea:  Anterior transparent portion of the eyeball

Ø Iris: Colored structure behind Cornea, which is opaque. The pigment density in iris decides on the color of our eyes. There is a hole in this iris through which light enters into the eye which is called “Pupil”.

Ø Lens: Transparent, crystalline structure behind iris, which helps in focusing the objects at distance and near.

Ø Aqueous humor: Transparent liquid between lens and cornea. The quantity and flow of aqueous humor decides the pressure inside the eye.


Posterior Segment: - This includes the structures behind lens i.e. Vitreous humour, Retina, Optic Disc, Choroid and Sclera.


Ø Vitreous humor: It is also a transparent liquid between Lens and Retina. This helps to keep the normal shape of the eye. Unlike aqueous humor, vitreous humor is in jelly form.

Ø Retina: It is the most important part of our eye. It acts like a film in a camera. It includes millions of neural structures which transfers all the light impulses into neural impulses. Macula is the place where retina has maximum vision.

Ø Optic disc: All the neuronal structures from retina joins at this point and traverses to brain through a common pathway called Optic nerve. The anterior portion of the optic nerve, which can be seen in dilated evaluation of retina is called Optic disc.

Ø Choroid: It is posterior to the retina. It is pigmented layer of tissues which helps in reducing scattering of light inside eye.

Ø Sclera: It is the outermost covering of the eye, part of which is seen outside in a whitish color. This is the structure where the eye muscles which help in moving our eyes are attached firmly to the eyeball. It is not transparent. It is continuous with cornea in front, where it becomes transparent for the light to enter inside the eye.



Protective Structures :

Ø Conjunctiva: The scleral tissues which are exposed outside and inner parts of eyelids are covered with another transparent and vascular tissue namely Conjunctiva.

Ø Tears: They help in lubrication and also protection of eyeball from infections to an extent

Ø Eyelids: Eyelids are the most outermost structures of the eye. They help to prevent direct injuries to eyeball to an extend.


external structures of eye