Eyeglasses

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by sk74z7mhs
Last updated 7 years ago

Discipline:
Science
Subject:
Physics
Grade:
10

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Eyeglasses

Eyeglasses are used to correct vision problems in children, teens and adults. The vision problems can range from nearsightedness, farsightedness and astigmatism. Nearsightedness also known as myopia is when objects at a distance appear to be blurred. Farsightedness or presbyopia is when objects that are close appear to be blurry. Lastly astigmatism can range in a variety of defects in the eye and the lens of the eye, which causes blurred or distorted images. For example the eye could be stretched horizontally causing the viewing angle to be tilted and create distorted images.

The vision problems that are diagnosed determine the kind of lens that is used. For example a person who suffers from myopia would require a concave lens because there eye is producing an image right before the retina so the far objects are blurry. The concave lens makes the refracted light rays diverge which allows a virtual, upright image to be formed on the retina. If the problem is presbyopia the image is focus behind the retina and makes it so that objects up close appear blurry. The convex lens eradicates this problem as it makes the light rays from the object refract in a converging pattern. This makes the image focus at the retina and make objects up close visible. Lastly astigmatism requires special lenses called toric lenses which are in a cylindrical shape. The cylindrical shape is put at a perpendicular viewing angle as that of the eye. This makes the eye have a rounded viewing angle and counters the astigmatism.

How do eyeglasses work?

Advantages: Prior to eyeglasses humans used emeralds and water in glasses as magnifiers. Current day eyeglasses are easier to manufacture as opposed to using emeralds as they do not require extracting a mineral from the ground. Eyeglasses are made according to each individual to ensure that each individual gets the most out of their eyeglasses. This makes eyeglasses more reliable as emeralds would give a magnification of a certain amount magnification that isn’t appropriate for everyone. The water in the glass does the same thing and therefore makes eyeglasses more reliable. Also they are more compact and require less care to keep than emeralds and water in glass.

The very first original pair of eyeglasses were invented in 1286 in Italy. However they were very different from what we think of when someone says eyeglasses. The first pair of eyeglasses were simply two pieces of glass placed on the eyeball. However the original inventor of eyeglasses still remains anonymous, but a man by the name of Alessandro Della Spina talked to the original inventor and then began creating his own eyeglasses. In 1301regulations were put into place to allow the sale of eyeglasses in Venice, Italy.

When and by whom were eyeglasses invented?

What are eyeglasses used for?

Eyeglasses

Disadvantage: The disadvantages of eyeglasses compared to the previous technology is that eyeglasses are more expensive compared to using water in a glass. Also eyeglasses have to be changed as the persons vision gets worse, this can be very costly as lenses have to be remade and new eye exams have to be done. Eyeglasses also have disadvantages compared to the newer technology like contacts. The frame of the eyeglasses sometimes blocks peripheral vision which can be dangerous when operating a vehicle. This is where contacts have the upper hand as they do not block peripheral vision. Eyeglasses can also be uncomfortable with the frame being extra weight, but contacts don’t have that problem as they are put directly on the eye.


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