What is the difference between butterfly and cat-eye sunglasses? | KOALAEYE OPTICAL

What is the difference between butterfly and cat-eye sunglasses?

What Are Blue Blocker Reading Glasses? Reading What is the difference between butterfly and cat-eye sunglasses? 7 minutes Next Are bifocals better than progressives?

Can you get prescription glasses for night driving?

It is recommended to choose prescription night driving glasses with an anti-reflective coating.When you're driving at night, you'll encounter several bright light sources, including the car's headlights, taillights, and street lights. These light sources can be a distraction for any driver, but especially for those with eye problems. The light reflected from these light sources can cause these drivers to temporarily lose sight of the road, which can lead to many unfortunate situations. As a result, the anti-reflective coating protects your eyes from nighttime brightness and daytime UV damage. The coating on the glass prevents the reflection of these light sources, allowing you to better focus on what's happening in front of your car. Meanwhile, prescription glasses with an anti-reflective coating can reduce glare and improve vision. Whatever prescription glasses you choose for night driving, make sure they have an anti-reflective coating.


Refractive index of spectacle lens

It is generally believed that the higher the refractive index, the better the spectacle lens. Such spectacle lenses are relatively thin, and of course, the price is a bit expensive. When the refractive index increases, the direction of the light entering the lens will change greatly, the focus will move to the lens, the focal length will be smaller, and the diopter will become larger. In order to keep the diopter unchanged, it is necessary to reduce the curvature of the lens, that is, to reduce the curvature of the mirror surface, so that the thickness of the lens can be reduced. This is why the larger the refractive index, the thinner the lens is. Under the same premise of other things, the larger the refractive index, the thinner the lens, the lighter and more beautiful the lens, and the higher the price, but the larger the refractive index is not the better.



About Polarized Sunglasses

Polarized sunglasses only absorb the reflected light of the object itself, presenting what is being seen, making the field of view clearer and thus reducing eye strain. In addition, the light through a bumpy road, water, and other places also can produce irregular diffuse light. The polarized lens can be this kind of optical filter, only absorbing the reflection of the object itself. Because of its high-efficiency filter layer, the UV blocking rate of the polarized sunglasses is 99%, which can effectively reduce UV damage to the eyes. And if you are driving, fishing, traveling, skiing, it is recommended to choose more powerful polarized sunglasses.


Lens anti-fogging agent

To be specific, a layer of the anti-fogging agent is sprayed (coated) on the surface of the lens to form a dense, absorbent, ultra-thin, and ultra-transparent biological coating. The coating chelates the droplets inside the coating (chelating means processing the material into a digestible form) to form a continuous and supper transparent chelating coating, which converts the droplets into a transparent micro-glass layer, thus preventing fogging. Spray anti-fogging agent on the surface of the lens, and then wipe evenly with an ordinary lens cloth. It can be used on most lenses. They are easy to use but have relatively short anti-fogging time. During use, the lens should not be wiped or washed. Long time use will affect the lens life.



What Are Progressive Lenses?

Traditional eyeglasses are usually single vision lenses with one prescription. Progressive lenses are multiple with three prescriptions in a pair of eyeglasses. Progressive lenses let you see comfortably at different distances, allowing you to see close, near, and far without changing your glasses. There are other kinds of multifocal lenses like bifocals and trifocals, but progressive lenses differ because of their smooth transition between prescriptions.

Bifocals and trifocals work similarly to progressive lenses and feature either two or three prescriptions in a pair of glasses. These lenses have definitive lines separating the prescriptions. However, progressive lenses don’t use these lines and allow you to easily transition between prescriptions.

Hence, in the following section, we will show you 6 different types of progressive lenses.


Progressive Lens

Standard progressive lenses are multifocal lenses with three observation areas, farsightedness, intermediate vision, and nearsightedness. Unlike bifocals, there are no visible lines between each viewing area. They have a seamless, invisible design, where the optical power changes 'gradually' throughout the lens. Many people confuse 'bifocal' or 'trifocal' with 'progressive' but remember that bifocals and trifocals have visible lines in the lens, while progressive lenses do not. Because progressive lenses have no lines in the lens, they are more popular multifocal lenses than bifocal lenses.

The main observation area of the progressive lens is a far distance, the smaller area at the bottom of the lens is used for myopia, and the middle area in the middle is smaller. Standard progressive glasses are very suitable for general purpose glasses, focusing on hyperopia activities (such as driving and walking) and sufficient area in the lenses for nearsighted activities (such as reading and computer use). The left and right sides or 'convex corners' of the lens are deliberately blurred to achieve an invisible design. The clearest line of sight in the gradual process is from the center to the top of the lens.


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What is the cheapest way to buy prescription glasses?

The choice of frames is not only good-looking but also has a lot to do with whether the polished glasses can be worn correctly. Therefore, special attention should be paid to the selection of spectacle frames, and the pupil distance and the optical center of the spectacle lens should be placed in a suitable position. It should also match the shape of the face so that the paired glasses are not only beautiful but also comfortable to wear. If you don’t choose a frame according to this, but choose anyone according to the general rules, the pupils will not match the optical center of the glasses, and the deflection center of the glasses will appear, causing the prism effect, which is very harmful to the eyes. How do choose a frame? Glasses are worn on the face after all, and they have a decorative effect, so you still have to see if they fit your face shape. In addition, the weight should be light and the frame size should be appropriate. It is best to measure the interpupillary distance, otherwise, it is easy to cause squint and cross-sight. It is safer for children to choose a plate frame with resin lenses. There is a wide range of options for adults. Glass lenses have higher hardness and are not easy to wear, while resin lenses have lower hardness but lightweight, good clarity, and higher protection against ultraviolet rays. Although crystals are expensive, they have high ultraviolet and infrared transmittance.

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