There are two parts to what the eye perceives – the object and the color of the object. Here’s how our eye functions in normal conditions:
How do we see objects
Vision is usually the dominant sense used by people with sight. The eye is the organ of sight and is shaped as an irregular hollow sphere. To get a better view let’s see the eye in a vertical section and enlarge the eye. Here’s the midline view of various structures in the eye that translate light into recognizable images, among these are the cornea the lens and the retina.
Light from a bulb can be used to show how the light translates light waves into images:
First the light passes through the cornea ( a clear dome-like structure covering the iris /cover part of the eye). The cornea bends or refracts the candlelight onto the lens. The light is then refracted the second time while passing through the lens, finally focusing on the retina. The retina is the light-sensitive part of the eye. This double refraction causes the image of the candle to appear reverse and turn upside down on the retina.
Fortunately, that’s not the end of the story or the world will appear upside down ;-). The image gets transferred right side up in the brain which is connected to the eye by the optic nerve. Impulses travel down the optic nerve to the occipital lobe of the brain which then interprets the image of the candle in the correct perspective.
How do we see color?
Light has three basic colors or frequencies that we can see they are red, blue and green. The high-frequency light looks violet and low-frequency light looks red and in between are the other colors having different frequencies. The color is a physical property of light itself.
The human eye has the retina which perceives color, it has two different light detecting cells called the rod and cones. The rod helps see in low light conditions whereas the cones are mainly of three kinds and they help us see and understand color.
There are mainly three types of cones that detect the three basic colors- red, blue and green. When we see a color the cone sends its own distinct signal to the brain depending on the frequency. You must be wondering, how we see other colors. Except for red, blue and green all the other colors are the mixture of these basic colors. When two different color frequencies interfere with each other we see another color.
For example, the red and green frequencies, when they enter our eye the red and the green cone detect this frequency simultaneously and hence a neither red nor blue is detected but an entirely different color called yellow is seen by our eyes. Amazing isn’t it, our eyes are very important to us but, imagine if something goes wrong…
Common causes of imperfect vision:
The shape of the eye is very important in keeping the things we see in focus. If the shape of the eye changes it affects the person vision. Let’s take a look at the Common causes of imperfect vision.
Cause: Normally light is precisely focused on the retina at a precise location called the focal point. The nearsighted eye is longer than the normal eye, that’s why the light is focused in front of the retina instead of falling directly on it. This makes it difficult to focus on things that are far away. A person with a long eye is referred to as near sighted.
Remedy: Concave lenses are used to correct this condition. The concave lens helps in focusing the light directly on the retina (the focal point of the retina).
Cause: Far-sightedness is when the length of the eye is shorter than the normal eye. Light is focused behind the retina making it difficult to see things that are close. A person with a short eye is referred to as far-sighted.
Remedy: A convex lens is used to correct farsightedness because it directs the focal point back on the retina.
The eye is a vital part of our senses and hence, we should take care of it. To know more about the concepts of Physics Chemistry or Biology your can simply click here.279 Views