Why do spectacle frames rust?
Before solving this problem, we can first understand the causes of rust spots on the frames and skin allergies due to rust spots. Many alloy products in daily life contain nickel, and direct contact with the skin will cause allergies to sensitive people. The temples and nose pads are the parts that contact the skin with a large area, especially the outer surface of the metal frame and the interior of metal containing a large amount of nickel. Through contact with the skin and erosion of sweat, the appearance of rust spots and skin allergies are caused. Once allergy occurs, it will cause contact dermatitides such as redness, swelling, itching, and yellow water on the surrounding skin.
The Customization of Glasses
For the first time, you must go to a professional medical institution for medical optometry. Before the age of 12, you should dilate mydriasis and optometry. After the age of 12, you should decide whether to dilate mydriasis and optometry according to the specific situation of the eyes. The lens must be smooth, transparent, without bubbles and particles, with a uniform texture. The hanging ear of the temple should be attached to the outline of the outer ear, and the tightness should be moderate, so as not to slip.
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Bifocal lenses have two observation areas separated by visible lines, a larger observation distance area, and a smaller reading area. It may take some time for people who are wearing bifocal glasses for the first time to get used to the lenses. This is mainly due to learning how to move the eyes between the observation distance area and the reading area. Some people will also find that there will be an 'image jump' phenomenon at the visible line between the distance and the reading area, especially for those with limited mobility, who must look down when walking. The best way to get used to bifocals is to wear them as much as possible.
What is a progressive lens?
Progressive multifocal lenses are lenses with different upper and lower powers for seeing far above and below for seeing near. The distance from the fixed far power above the lens to the near power fixed below the lens does not change suddenly, but a gradual transition between the two through the gradual change in refractive power. Compared with ordinary lenses, there are many advantages. The appearance of the lens is like a single vision lens, and the dividing line of the power change is not visible. Not only is the appearance beautiful, but more importantly, it protects the age privacy of the wearer, and there is no need to worry about revealing the age secret due to wearing glasses.
Since the change of the lens power is gradual, there will be no image jump. It is comfortable to wear and easy to adapt. So it is easy to be accepted. Because the degree is gradual, the replacement of the adjustment effect is gradually increased according to the shortening of the short distance. There is no adjustment fluctuation, and it is not easy to cause visual fatigue. Clear vision can be obtained at all distances in the visual range.
Such a pair of glasses meets the use of long-distance, near-use and various distances in the middle at the same time. It is especially good news for teachers, doctors, music workers, and computer operators, because these people not only need to see far and near objects clearly, but most of the time they also need to be able to see middle distance objects such as blackboards, piano scores, and computer screens. . This is not possible with any lens other than progressive lenses.
Production technology of progressive lenses
In addition to the evolution in design, the production technology of progressive lenses is also constantly improving: the most representative one is the free-form technology. The emergence of free-form surface technology makes the production more flexible and rapid and can realize a more personalized design. For now, progressive lens design is done on the inside surface of the lens by a computer-controlled lathe, as if a master engraver could carve a piece of stone into a work of art.
Confirm the optometric data
It is necessary to confirm the accuracy of optometric data. If you stay up late or look at the phone or computer for too long before the optometry, leading to visual fatigue, it will increase the degree. But if you can let your eyes have a good rest, and then take optometry, the degree may be restored to the original situation, so you need to know the state of optometry, to check if it really had increased in degrees. The main purpose of progressive lens is to use it for people who have bleached eyes and often take off the lens.