Eyes: World inside the Retina

Eyes are one of the most fascinating and complex organs of our body. Upon visiting a doctor, one of the first things he does is examines your eyes. Why? It is because, just a glance at the eyes gives an insight to the health of an individual. Eyes are one of the most important senses, more of the brain is dedicated to seeing than any other senses.

Human eyes are just lenses with a resolution of 576 megapixels, which captures light, but what we actually see is an interpretation by our brain, so the brain sees through our eyes. Everything we see through our eyes is an upside down image of an object, our brain interprets the image the right way.

It is one of the fastest muscles in our body and responds to a stimuli quicker than any other part. Human eye reacts to pressure and is light-sensitive which allows vision. It provides a three-dimensional view of all its surroundings. Eyes are enclosed in a eye-socket made up of several bones fixed to the skull forming a four-sided pyramid like structure.

A brief mechanism of eyes: Light enters pupil and is focused at the back of the eye onto the retina. Retina converts this light received as a signal into electrical impulses. Optic nerves present is responsible to carry these signals generated to the brain where impulses are processed further.

Structure Of The Eye

Structure of eye is mainly composed of tissues, containing specialized cells. Tissues of the eyes consists of three layers, namely:

  • Light is focused on refractive tissues
  • Tissues sensitive to light
  • Tissues providing support

Refractive Tissues

These tissues consist of the pupil which is a dark spot in the centre. It expands and shrinks as a result of responding to light. The coloured portion of the eyes is called the Iris which is a muscle governing the amount of light entering the retina. Light after travelling through pupil enters the lens which is convex in nature. Process of accommodation takes place through the ciliary muscles which are muscular rings. The Cornea covers the pupil and is responsible for the focusing power of the eye. It consists of nerve fibres. There are two fluids flowing through eyes: The Vitreous fluid and the Aqueous fluid.

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Light-sensitive Tissues

It is the innermost layer of the eyes and consists of rods, cones and optic nerves. It consists of photoreceptors and converts light into electrical impulses.

Support Tissues

These tissues are fibrous in nature and provide support and structure to the eyes. Generally called the white of the eyes, it consists of the following parts: Sclera, Conjunctiva and Choroid.

Hence eyes are just lenses, the actual vision processing is carried out by the brain. Different parts of the brain are involved in reading and interpreting information. Human brain consists of three main parts – Cerebrum, Cerebellum and the medulla oblongata. The Occipital lobe situated at the back of the brain above the cerebellum is responsible for vision. Visual Cortex is part of the brain where sensory and motor information is integrated with vision.

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