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Types of Prescription Glasses
Prescription lenses are the heart of what makes a pair of glasses provide the sharp, clear vision you want to have. There are several types of prescription eyeglasses to address your visual needs, whether you are nearsighted, farsighted or need multiple prescriptions in one lens:
Single Vision – Single vision prescription lenses are used to correct a single vision problem such as nearsightedness, farsightedness, astigmatism. They contain the same amount of vision correction throughout the entire lens. In terms of single vision reading glasses, full frame readers are the most common. You’ll also find single vision lenses in half frame reading glasses which are narrower and sit at the end of your nose for easier up-close and distance viewing.
Multifocal Lenses – People who have more than one vision problem often need eyeglasses with multifocal lenses. Multifocal lenses, such as bifocals and progressive lenses, contain two or more vision-correcting prescriptions.
Bifocal – Bifocals contain two prescriptions within the same lens. The eyeglass lens is split into two sections; the upper part is for distance vision and the lower part for near vision. When you’re looking at someone who is wearing bifocals, you can often see the line between their nearsighted and farsighted prescription.
Progressive – Progressives are multifocal lenses that contain three main fields of vision including near, intermediate and distance. However, progressives do not have a visible line between prescriptions. This gives the wearer a seamless and uninterrupted transition when looking from up-close objects to far-away distance.
Computer Glasses – The lenses of computer glasses are designed to deal with eyestrain caused by computer screens. Computer glasses help with an intermediate distance of around 20 to 26 inches, which is the distance most people sit from their monitor. Many computer glasses have tinted lenses to block out blue light radiating from your electronic devices.
Reading – Even if you don’t have an eyeglass prescription from your eye doctor, you may find yourself needing reading glasses. A valid prescription is not required to purchase reading glasses, though your eye doctor can tell you the magnification you need.
Which Is Better Bifocal or Progressive Lenses?
When you are now thinking about which lenses you should choose. Stay with me because we will break down exactly the pros & cons of progressives and bifocals for you.
In most cases, progressives are a better choice. Because they provide a continuous clear vision from far to near and in between. Although you need to plan in a little more time to get used to them due to the blurry sides. Progressives also look better because of the missing line. And if you need a strong reading zone they will not have a blurry gap in front of you. But you will learn in the article when each of them would work better.
Usually, bifocals have a bigger reading segment. However, this depends on what kind of segment you choose in your bifocal lenses. There is a variety of them. You can choose between different shapes of the reading segment and different sizes. The standard bifocals come with a shape that has a flat or slightly rounded top and has a semicircle shape in the bottom. The size of it varies between 25-28mm which gives you as a wearer the ability to perform really big eye movements as you read your newspaper.
But bifocals just provide you with only one sharp distance. Compared to bifocals, progressive lenses have a smaller reading zone that gives lets you see two to three articles clearly in your newspaper depending on your prescription. But progressive lenses enable you to have every distance sharp between the distance vision and the near range which bifocals do not. In progressive lenses, you can not really choose the size of the reading zone but you can stretch the transition into the reading zone a bit more to get more out of the middle distance.
On the one hand, really short progressive glasses will have a smaller zone for the middle distance like your laptop and you do not have to look down as much while reading. On the other hand, you get really long progressive lenses to force perform bigger eye movements down to be able to read. But therefore you get a slightly bigger reading zone.
Blue Light: the good and the bad
The light that reaches and enters the human eye is divided into visible light, comprising wavelengths from 380 to 780 nm, and non-visible light, which includes light in the ultraviolet range (UV light) and the infrared range (IR light).
Experts have been aware for some time that UV light can potentially damage biological tissue, such as our skin and eyes. That is why people typically take precautions to protect themselves from the sun, using items such as sun cream or a pair of sunglasses. However, visible blue-violet light also has the potential to cause damage to our eyes. Although blue-violet light has less energy than ultraviolet light, it is almost entirely unfiltered as it passes through the eye and reaches the retina. By way of contrast, ultraviolet light is almost entirely absorbed by the front part of the eye, and significantly less than 5% of it reaches as far as the retina.
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