Losing one's eyesight is the same as losing a navigator through the world. This is because this front sight organs are of vital importance for all living organisms. There have been many evolutionary steps to ensure that living beings are able to see in the best possible way.
Eyes are believed by scientists to have evolved at about the same time as the first animals (during the Cambrian explosion) in one species and within a few million years had spread to most of the others. No other sense organ is more common among the animals, probably a measure of the eye's utility. With the eyes usefulness also comes it's vulnerability due to it being constructed of mostly soft tissue.
Eyes in all animals differ in the way they are protected. In humans, this protection is threefold: firstly, the eyelids protect and water the eye. Secondly, the soft eyeball is situated in a resistant shell made of bone. Thirdly, a membrane surrounds it to protect it from outside influences. It is only natural that the human body has evolved to preserve the eye as much as possible. Therefore, people should also take extra care of their eyes so as not to lose the wonderful possibilities of eyesight.
Explaining the basic working principle of the eye is simple, despite this, human beings are yet to create a device that even comes close to matching the eye's function. This is because the light is not simply a light detector, but does what it does through a complex interaction with the brain. In fact, it would take a powerful super computer to model the visual cortex on it's own.
One of the most surprising things you would find if you were to do a survey of sight and sight organs among all the animals is the range of eyes that are out there. There are believed to be more than 10 distinct kinds of eyes existing in nature currently, some having evolved independently of each other. This goes back to the earlier point about the evolutionary utility of sight.
Human eyes can detect color, depth and direction to a reasonable degree, but there are birds that can see in UV. There are also microorganisms that have eyes that do nothing but distinguish light from dark. The mantis shrimp has hyper-spectral vision and probably possesses the most complex color vision system among all animals.
The functioning principle behind a camera, telescope, microscope or any other light-focusing device is the same as the one in the human eye. Once light enters the iris, it is focused in the direction of a small patch of photosensitive cells. The iris can be expanded or shrunk to increase or limit the amount of light that enters the eye. While the initial stage does not differ, what follows afterwards is radically different and undeniably more complicated.
Things are relatively simple before the light reaches the rods and cones (the light sensitive cells) but afterwards become appreciably more complex and as yet no convincing explanation of how people actually see has been put forward by the scientific community. The eye is a fascinating instrument and more still remains to be known about it. This is one reason why everyone must take every precaution to keep his or hers healthy, imagine losing such a wonderful gift!
Eyes are believed by scientists to have evolved at about the same time as the first animals (during the Cambrian explosion) in one species and within a few million years had spread to most of the others. No other sense organ is more common among the animals, probably a measure of the eye's utility. With the eyes usefulness also comes it's vulnerability due to it being constructed of mostly soft tissue.
Eyes in all animals differ in the way they are protected. In humans, this protection is threefold: firstly, the eyelids protect and water the eye. Secondly, the soft eyeball is situated in a resistant shell made of bone. Thirdly, a membrane surrounds it to protect it from outside influences. It is only natural that the human body has evolved to preserve the eye as much as possible. Therefore, people should also take extra care of their eyes so as not to lose the wonderful possibilities of eyesight.
Explaining the basic working principle of the eye is simple, despite this, human beings are yet to create a device that even comes close to matching the eye's function. This is because the light is not simply a light detector, but does what it does through a complex interaction with the brain. In fact, it would take a powerful super computer to model the visual cortex on it's own.
One of the most surprising things you would find if you were to do a survey of sight and sight organs among all the animals is the range of eyes that are out there. There are believed to be more than 10 distinct kinds of eyes existing in nature currently, some having evolved independently of each other. This goes back to the earlier point about the evolutionary utility of sight.
Human eyes can detect color, depth and direction to a reasonable degree, but there are birds that can see in UV. There are also microorganisms that have eyes that do nothing but distinguish light from dark. The mantis shrimp has hyper-spectral vision and probably possesses the most complex color vision system among all animals.
The functioning principle behind a camera, telescope, microscope or any other light-focusing device is the same as the one in the human eye. Once light enters the iris, it is focused in the direction of a small patch of photosensitive cells. The iris can be expanded or shrunk to increase or limit the amount of light that enters the eye. While the initial stage does not differ, what follows afterwards is radically different and undeniably more complicated.
Things are relatively simple before the light reaches the rods and cones (the light sensitive cells) but afterwards become appreciably more complex and as yet no convincing explanation of how people actually see has been put forward by the scientific community. The eye is a fascinating instrument and more still remains to be known about it. This is one reason why everyone must take every precaution to keep his or hers healthy, imagine losing such a wonderful gift!
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