Eyeglasses

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by sp8v4tse7
Last updated 5 years ago

Discipline:
Science
Subject:
Physics
Grade:
10

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Eyeglasses

History of Eyeglasses:

Eyeglasses

• You don’t need to replace your glasses frequently (saves money in long term compared to contact lenses)• Most adults, children, and infants can wear glasses.• Less expensive than getting laser eye surgery to correct your vision• Easier to take care of compared to contact lenses• Unlikely to cause side effects because it doesn’t directly touch the eyeball• It is easy to find them in stores and can be easily be replaced as your vision changes• Glasses can protect your eyes from injuries (such as something getting in your eye).

• Lens reflection and glare (especially when taking photos)• Can become uncomfortable on your face, especially around the nose (because of weight)• Cannot wear them for sports because it can easily break and it is dangerous• Eyeglasses can be broken or lost.• Some people find glasses inconvenient, uncomfortable and annoying (they tend to fog up in humid or cold environment• Cannot take them under the water • Prevents you from applying for certain jobs because it is dangerous or not allowed (e.g., firefighters, lifeguards and etc.)

Advantages:

Disadvantages:

How the Eye Can See:When someone has very good eye vision, the light rays enter through the cornea, then the pupil, lens and finally retina. The cornea and lens refract the light so it can focus on to the retina. The retina forms an inverted image and then the brain makes the picture upright.

Eyeglasses are made from two major components which include the frame and lenses. The frame keeps the whole structure in place and enables the individual to actually place it on their face, so the lenses can do their job. However, refractive errors make images blurry because the light is not being refracted towards the retina. This is due to the eye’s shape. On the other hand, you can fix where the light rays land by wearing glasses with concave and convex lenses. So, when you wear glasses with concave lenses, you are nearsighted, meaning the light rays lands in front of the retina. Concave lenses are divergent lenses, so these lenses refract the light ray before it can reach the cornea. In result, the light rays refract outwards and now the light rays are focused on the retina. So, now you can see far object clearer than without eye glasses. Moreover, when you need to wear glasses with convex lenses it shows you are farsighted, meaning the light ray lands behind the retina. Convex lenses are convergent lenses. So, the light rays refract inward before the light rays reach the cornea. Now the light rays are focused on the retina, so now you can see objects near you clearer than without eyeglasses. To sum it up, concave and convex lenses refract the light so; it can focus on to the retina, making the image a lot clearer.

How Eyeglasses Work:

Many individuals use eyeglasses to correct or improve their eye vision with the help of the lenses in the eyeglasses. There are many possible reasons which could include refractive errors (myopia and hyperopia) and also because of old age (presbyopia). First of all, myopia also known as nearsightedness occurs when the individual’s eye is larger than an average eye. This causes the light to land in front of the retina, whereas a person with very good vision has the light focus on the retina. In result, these individuals can see clearer when the objects are near them, however objects that are farther are blurry to them. To fix this, the person should get eyeglasses that have concave lenses. In result, they are able to see objects that are farther from them better than without glasses. For example, it can be used to watch TV, look at the whiteboard and etc. However, people with high myopia might have to wear their glasses all the time. Secondly, hyperopia also known and farsightedness occurs when the individual’s eye is smaller than an average eye. This causes the light to land behind the retina, which causes the individuals to see clear only when the item is far away from them. However, when they wear glasses with convex lenses, they are able to see clear even if the item is near them. You can use this type of glasses for reading, sowing and etc. Lastly, presbyopia is an eye condition which everyone develops over time. People who are 40 years old and onwards usually develop this condition (a normal process in everybody’s life). Practically, the lens in the eye loses it ability to focus on nearby objects. Some people can manage without glasses even with this condition, but others might have to get the eyeglasses. So, individuals who develop presbyopia can correct there vision by wearing glasses like reading glasses.

Why and What Eyeglasses are Used For:

Eyeglasses are one of the oldest optical devices that humans use regularly on a day to day basis. There is no exact date or inventor which causes many dilemmas. Additionally, many historians believe that monks or craftsmen in Italy produced the first form of eyeglasses. The frame was made out of metal or bones and the lenses were made out of quartz. However, the first recognized pair of glasses that wear wearable was invented by Salvino D’Armate in around 1285. In the 14th century the convex lenses were invented to correct hyperopia. Later on in 1451, Nicholas of Cusa in Germany invented concave lenses to correct myopia. All in all, many people contributed to make this optical device a functional and useful device to improve eye vision for humans.

Myopia

Hyperopia

Here is an optometrist who explains how eyeglasses work:

First wearable eyeglasses

Anatomy of Eyeglasses


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