Is it a good idea to buy glasses online?
If the product is purchased from a reputable and trusted retailer, buying glasses online is just as safe as buying any other product online. Buying custom-made products, such as 'prescription glasses' online, is a bit more complicated than buying regular 'ready-made' glasses. All uploaded prescription glasses orders are reviewed and notified when serious errors are found in the prescription. All prescription glasses to be shipped are also carefully checked by quality control personnel to ensure that the glasses match the required prescription to the highest standard.
What is the best lens material?
Early lenses were made of natural materials because they were easy to get. But natural materials have obvious drawbacks. According to records of the Qing Dynasty, Emperor Yongzheng wore crystal glasses given by the imperial court, which greatly improved the efficiency of reading documents. However, because of the cold nature, the crystal will make the temperature around the eyes low when wearing, and part of the crystal lens has color so that the light into the eyes becomes soft.
How do you know Ray Ban's frames are real?
Ray-ban Spectacle Case
The true Ray-ban spectacle case has good workmanship and thick leather. The case is covered with flannel. There are MADE IN ROMANIA words in the case. The leather of the imitation is rough and has two layers, one of which is pure hard plastic.
Ray-ban glasses lens cloth
The authentic Ray-ban glasses lens cloth is silver-gray, with the Ray-ban logo, and the lens cloth is shorter than the regular glasses cloth. The imitation is different in color, lacks hierarchy.
Ray-ban glasses ear rests
The authentic Ray-ban eyeglass glasses ear rests are made of metal, comfortably wrapped, and removable. The copies are not filled, and some cannot be taken off at will.
Ray-ban Glasses manual
There is not much difference in the instructions. The red part of the original is lighter than the imitation.
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.
Acetate is a kind of thermoplastic resin obtained by esterifying acetic acid to acetic anhydride under the action of a catalyst. Acetate is resistant to water, gasoline, mineral oil, and lipids, weak alkaline solutions, and acids, excellent weather resistance, not resistant to ethanol, strong acids, and strong alkaline solutions. During thermoforming, it is very necessary to dry the material before forming. Acetate was born in the early 20th century, and was successfully trial-produced and industrialized by the UK in the early 1920s. At present, it is the second-largest variety in cellulose fiber after viscose fiber. Acetate can be used to make textiles, cigarette filters, film bases, and plastic products.
Contact Lens Materials - Nesofilcon A and Omafilcon A
Nesofilcon A is super water glue. This is the proprietary material of Bausch & Lomb and is now used in only one product, the Bausch & Lomb Pure Suncast (launched in the US in 2012). Water content is 78%, and the oxygen permeability is DK/T =42.
Through PC Technology, the Omafilcon A material contains substances that mimic the composition of cell membranes--- including human eyeball cells, and locks water, and prevents dryness.
About the Glasses Direct
Glasses Direct is an online professional eyewear shopping site based in the UK, with the leading online sales volume in Europe. Over the past five years, its online sales have increased by 50%, and it has had more than a million customers. Since 2004, they have been providing affordable glasses with uncompromising quality and professional service. The frames selected included big brands like Ray-Ban and Oakley and came in a variety of shapes and sizes. Its main goal is to provide a convenient option for people who need corrective glasses.