Possible effects of driver's lens color on driving
Color plays a very important role in your everyday driving experience -- red, yellow, and green traffic lights, among many other signs and signals, are designed to grab your attention and keep you safe. If everything you see is yellow, you may make the wrong decision at the red light and may cause an accident. To keep your vision clear in night and day conditions, anti-glare night driving glasses are not just for night driving.
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.
What Is Progressive Lens?
Progressive lenses, also called multifocal lenses, have three prescriptions in one pair of glasses. So, it allows you to see near, middle distance, and far objects without changing your glasses. The progressive lenses are designed for people who are over 40 years old who are both nearsighted and farsighted. The progressive lenses come with the following features:
- There is no distinct line between all visions(near, intermediate, and far).
- Most popular lens for anyone with presbyopia who wears
- Expanded intermediate zone for better computer vision.
From the above information, you may have known the differences between bifocal lenses and progressive lenses. As for progressive vs bifocal lenses, which one is better? It is difficult to judge because each of them has unique features. So, if you do not know choose which, you can listen to the eye doctor.
How to Find Reading Glasses Strengths?
Some reading glasses also come with strengths. So, how do you know what strength reading glasses to get and how to find reading glasses strengths? The strength of all reading glasses is measured in dioptre, with units increasing by 0.25 dioptre depending on the power of the lens.
The reading glasses strengths range from +0.75 dioptre to +3.00 dioptre. Both lenses have the same power which is indicated by a permanent marking on the inside of the frame or with a removable sticker on the lens. So, you can find the reading glasses strengths of the glasses.
The important thing you need to notice is that when higher the number, the greater the power of the lenses is when choosing reading glasses. So, glasses with a marking of 1.0 are low power while those marking +3.0 are high powered.
General glasses material has plastic and metal two categories. Because the children's glasses degrees change faster, from the economic point of view, choosing plastic material is more affordable. And children love to move, they do not pay much attention to pick up and put on glasses. Choosing metal material is easy to distort, affecting the normal wearing. The material of the lens should be light and thin. The transmittance and refractive index should be high, and it should be wear-resistant and not easy to break.
Understand the basic knowledge of prescription of glasses
The prescription mainly includes the refractive status of the eye, degree of correction required, pupil distance, and the purpose of using the lens. Nowadays, there are many brands and varieties of glasses. Glasses are usually classified according to the material, structure, and use of the lens. Most of the glasses in the prescription are classified by structure. Nowadays, single vision glasses and multi-focal glasses are mainly used, and multi-focal glasses include bifocal glasses, three-lens glasses, and progressive multifocal lenses.
Buy Glasses For Kids - Appropriate Frame
To choose a frame for the child, we must first consider the measurement of the bridge of the nose of the child, and the pupil distance. Furthermore, if the eye is farsighted and the pupil distance is too large, it will produce the prism effect from the bottom out. If it is myopia and the pupil distance is too large, it will produce the prism effect bottom-inward. If the pupil distance is too small, it will have the opposite effect. The frame should be light, light glasses will not affect the development and shape of the child's nose bone.