How your eyes work

The eye is one of nature’s complex wonders. It is a specialized sense organ that reacts to light, processes it and then transmits information to the brain.
Your eyes are able to distinguish around 10 million colours. But it’s your brain that actually does the ‘seeing’. The eyes act only as a ‘central processor’, taking information, in the form of light waves, and transmitting it to the brain.
In a number of ways, the human eye works much like a digital camera:
1. The Cornea and the lens provide focus.
2. The Iris does the work of the camera aperture.
3. & Retina plays the role of the film on which inverted image of the objects are formed.
4. This image is then send to the brain via the Optic nerve where it is processed and we see an upright image.

A closer look at the parts of the eye

Conjunctiva

The conjunctiva is the clear, thin membrane that covers part of the front surface of the eye and the inner surface of the eyelids. It keeps the front surface of the eye and inner surface of the eye lids moist and lubricated. It has two segments.

Bulbar conjunctiva.
Palpebral conjunctiva

Cornea

The cornea is the outermost layer of the eye. It lies directly in front of the iris and pupil, and it allows light to enter the eye.

Eyelid and Eyelashes

The eyelids serve to protect the eye from foreign matter, such as dust, dirt, and other debris, as well as bright light that might damage the eye.

The eyelashes help filter out foreign matter, including dust and debris, and prevent these from getting into the eye.

Orbit

The orbit is the bony eye socket of the skull. The orbit is formed by the cheekbone, the forehead, the temple, and the side of the nose. The eye is cushioned within the orbit by pads of fat.

Pupil

The circular opening in the center of the iris through which light passes into the lens of the eye. The iris controls widening and narrowing (dilation and constriction) of the pupil.

Iris

The iris regulates the amount of light that enters your eye. It forms the coloured, visible part of your eye in front of the lens. Light enters through a central opening called the pupil.

Optic Nerve

The 1.2 million optical nerve fibres connecting to the eye and terminating in the brain where images are created and processed.

Retina

Light processing membrane; converts light into electrical impulses that are transmitted to the optic nerve.

Tear film

A very thin film of water and other chemicals riding on top of the corneal epithelium (surface) that lubricates the front of the eye.

Other Terms:

Dry eye

A syndrome characterised by corneal dryness due to deficient tear production.

Keratoconus

A rare inherited condition of the cornea in which the cornea is steepened to the point of being cone-shaped. Keratoconus is a form of Ectasia.

Under-correction

The result achieved when desired change in refractive error is not fully achieved.

Cataract

A cataract is a clouding of the lens in the eye. Vision with cataract can appear cloudy or blurry, colors may seem faded and you may notice a lot of glare.

Glaucoma

Glaucoma is a group of diseases that can damage the eye’s optic nerve and result in vision loss and blindness. It is usually associated with high pressure in the eye and affects side or peripheral vision.

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