Can't Use Alcohol To Clean Glasses
Generally speaking, alcohol is not suitable for cleaning resin lenses. Resin lenses are relatively soft and are usually coated with a film. It not only improves the hardness of the lens, but also has more other functions. The lens film is not suitable for cleaning with harsh cleaning agents. As we all know, alcohol has a certain stimulating effect, so it is harmful to the film of the lens.
What Are Progressive Lenses?
Your eyes change with your age. When your reach your 40s, you may find that it is difficult for you to focus between a book, a website on a computer screen and the conference room whiteboard. Progressive lenses are growing in popularity among people who need help seeing near, far and in-between.
Progressive lenses have grown in popularity and are one of the most common solutions to treat vision loss that occurs with age or presbyopia. Progressive lenses have a seamless increase in magnification from the top to the bottom of the lens, helping you see clearly at all distances with just one pair of glasses. The top portion of the lens enables you to see the far-away objects, the middle portion of the lens enables you to focus on the intermediate objects and the bottom to see objects close-up. The prescription changes little by little across the lens surface providing a gentle transition.
After knowing what the progressive lenses are, do you know what are the pros and cons of progressive lenses? If not, keep on your reading and we will show you some information.
What is the processing technology to make the lens thin?
For myopic lenses, the larger the diameter, the thicker the edge. Therefore, for customers with high myopia, we will recommend frames with smaller ring diameters, so that the edges of the processed lenses will be thinner. The edges of farsightedness lenses are already very thin (convex lenses are thick in the middle and thin on the sides), and the key determinant of lens thickness is the center thickness. In addition to the refractive index, which affects the thickness of the farsightedness lens, the influence of diameter is more important. Therefore, for patients with farsightedness, the most effective way to make lenses lighter and thinner is to choose a smaller frame and then customize a pair of lenses with the right diameter.
Why do people like wearing rimless glasses?
Suitable for a Variety of Face Shapes. The rimless glasses can perfectly present the lens without the wrapping of the frame, hence, they are very ornamental. Rimless glasses work on all face shapes, even if you have a heart-shaped face, a round face, a square face, or the enviable oval face. Compared with thick-rimmed glasses, rimless glasses do not cover too much face shape and can show the wearer's style and temperament. People with small faces will have a better wearing effect.
Why is a prescription for glasses different from a prescription for contact lenses?
The frame glasses degrees are the optometric degrees of the eye, and the difference between the frame glasses degrees and the contact lens degrees is mainly due to the different contact distances between the two lenses and the eye. Usually, degrees of contact lenses and glasses need to be converted by a professional through vertex diopter. The conversion formula is Fc=Fs/(1-d×Fs). In the formula, Fc is the diopter of contact lens, Fs is the diopter of glasses frame lens, and D is the distance between frame glasses lens and cornea. Assuming that the prescription of frame glasses is -4.00d and the distance between lens apex is 12mm, the prescription of contact lenses is -4.00/ [1-0.012×(-4.00)] = -3.82d.
The benefits of bifocal glasses
People with myopia often need to wear bifocal glasses after the appearance of presbyopia. The upper and lower parts of the lens have different diopters. The upper part is used to see distant objects, and the lower part is used to read and do close work. In addition to presbyopia, some people who work long hours in close quarters need bifocals to reduce eye strain. Studies have shown that long-term nearsightedness is the main cause of myopia. According to the adjustment principle of the eyeball and the height of the patient diopter, a reasonable measure is to wear myopia glasses with full correction when seeing the blackboard in class. When reading and writing. they should take off glasses or wear low myopia glasses. But the practice of continuously removing and putting on or changing glasses is clearly unrealistic. Bifocal glasses will solve this problem.
Disadvantages of Progressive Lens
There are deformation areas under the left and right sides of the lens, which make the image blurry and irregular. It takes 1-3 weeks to get used to it. In addition, it has a narrower field of view in the near and middle distances, and long-term concentration on the narrow focal point can easily make the eyes tired. Suitable for people who need to alternate between distant, medium, and near vision.
However, with the development of science and technology, more and more progressive multifocal glasses have emerged that have a wider field of view, more comfortable wearing, and better meet the needs of eyes. Nowadays, the use rate of progressive lenses among middle-aged and elderly people abroad is quite high. Single-lens and double-lens reading glasses are gradually being replaced by progressive multifocal glasses.