Why do old people wear wrap around sunglasses?

5 Signs You Need Reading Glasses

In this section, we will list some signs you need reading glasses.

1. You are over 40 years old. Everyone’s eyesight changes at a different rate, but most people develop presbyopia in their 40s. Presbyopia is a condition in which the eye strain to focus on nearby objects, which is different from farsightedness, a condition in which you can see distant objects clearly, but objects nearby may be blurry. Farsightedness is usually present at birth, but presbyopia develops during the aging process.
2. If you find that you never seem to have enough light when reading, regardless of the room type or the number of lamps you have turned on, it may be time to get reading glasses. According to a study, a 60-year-old people requires three times as much light as a 20-year old to do the same task.
3. If your eyes get tired when reading or working at your computer, you may need reading glasses. Do you find yourself dozing off at your computer, or do your eyelids get heavy when your reading or do detailed work? If so, you may be developing presbyopia, and you may need the reading glasses.
4. Another sign you need reading glasses is that you are getting more headaches. Consistently straining your eyes to read or focus on craft could give more headaches. A headache right behind your eyes could be indicative of hyperopia. It is important to remember the 20-20-20 rule: every 20 minutes, look at something at least 20 feet away for 20 seconds. If your headaches persist, you should see an eye doctor and have a check.
5. If you see halos, you may need reading glasses. When your lens cannot focus light into your retina, it makes your vision appear blurry. Thus, reading glasses can solve this problem.

Do I need reading glasses? After reading this post, you may have a basic understanding. If you need a pair of reading glasses, try Koalaeye glasses. They are stylish and cheap, and the glasses will be mailed to you with great convenience.

Choose the cost-effective glasses.

Choose your favorite glasses online. Open the shopping website, and select a store with high credibility. Choose your favorite glasses according to the style, lens, frame color, blue light blocking, radiation protection, and other factors, and then communicate with the customer service about the thickness of the lens and other specific details. If you see the frame is not suitable for yourself, you can communicate with customer service ahead of time to see whether you can buy the frame to send freight insurance. If it is not suitable, can we return it for a refund? To buy a store with a high reputation, you can look at the store's good comments and bad reviews. Talk to customer service. Sometimes there are hidden discounts.

What is blue light?

To prevent blue light, we must first understand what blue light is. The visible light with a wavelength range of 400-500 nanometers is called blue light. The light sources used in daily LED lighting and display products, including mobile phones, flat panels, and TVs, are mostly LED light sources excited by blue light. However, not all blue light is harmful to the human body. The human eye has an extremely low tolerance to blue light radiation in the 400-440 nanometer range. When the light intensity enters this threshold, photochemical damage is likely to occur. However, blue light radiation in the range of 459-490 nanometers is essential for regulating the human body's circadian rhythm and can affect the secretion of human melatonin, which in turn has an impact on the body's biological clock, alertness, and mood.

Scientifically effective anti-blue light lenses must not only block harmful blue light but also cannot filter beneficial blue light. Most of the ineffective anti-blue light products on the market currently have two types of problems. One is that there is almost no protective effect on the blue light in the vulnerable zone of the human eye. The other is excessive protection, shielding the blue light spectrum in the beneficial band so that the blue light that is beneficial for physiological adjustment cannot enter the human eye. At the same time, the color of the lens is yellow, which is prone to color shift, aggravating visual fatigue, and even inducing the risk of myopia.

Cellulose Acetate

Acetate is a kind of thermoplastic resin obtained by esterifying acetic acid to acetic anhydride under the action of a catalyst. Acetate is resistant to water, gasoline, mineral oil, and lipids, weak alkaline solutions, and acids, excellent weather resistance, not resistant to ethanol, strong acids, and strong alkaline solutions. During thermoforming, it is very necessary to dry the material before forming. Acetate was born in the early 20th century, and was successfully trial-produced and industrialized by the UK in the early 1920s. At present, it is the second-largest variety in cellulose fiber after viscose fiber. Acetate can be used to make textiles, cigarette filters, film bases, and plastic products.

Driver's protective glasses

The principle of the driver's protective glasses is to use the special film on the glasses to reflect the strong light hitting the glasses back to protect the eyes. It can protect against ultraviolet, infrared and blue light on foggy and rainy days. In snowy weather and at night, the wearer can see the scenery more clearly, and it can also increase the vividness of red, yellow, green, white, and other colors, and eliminate the glare and reflected light of the oncoming cars when meeting cars at night.

Semi-rimless glasses give you a wider view than full-frame glasses.

It is believed that many people who wear semi-rimless and full glasses will have experience greatly. Because semi-rimless glasses have no frame at the bottom, our view expands as we look down, unlike full-rimmed glasses. When looking down, the line of sight is blocked by the lower half of the frame of the glasses, which is very inconvenient.

Injection frame

Acetate cellulose pellets are extruded by an injection molding machine, which is called an injection frame. Its characteristic is that it saves raw materials, can be mass-produced, has a lower cost, and is cheaper than a plate rack. But the firmness is not as good as the plate frame. However, injection frames are mostly used for glasses for the elderly and children because of their lightweight and resistance to allergies. The injection frame is made of laminated plastic. It is made by pasting a thin layer of plastic of one color on another thicker layer of plastic. Thick materials are mostly transparent pigments. It is also made of three or more layers of plastic.