How to buy contact lenses online?
Choose a standard retailer. Contact lenses belong to three types of medical device products, and the sale of contact lenses and their care solution belongs to medical behavior. No matter it is an optical shop or contact lens e-commerce website, it must have a Medical Device Trading Permit before it can be sold. The trend of buying contact lenses online is obvious, and there are a lot of websites of individuals and contact lenses that do not have business licenses. Therefore when the user buys a contact lens on the net, be sure to look for management qualification of Medical Device Trading Permit, guard against being cheated.
The frame materials
You should choose the driver's glasses with alloy materials. The glasses made of this material are light and strong, so your ears won't be uncomfortable when you wear them for a long time.
How to Test Blue Light Glasses (Amber and Red Lenses)
This section will show you how to test blue light glasses with amber or red lenses.
1. The Black and Blue Squares Test
1. Prepare black and blue paper.
2. Wear your blue light glasses after sunset and check whether both paper appear black.
3. If they do not appear black, your blue light glasses can’t block all blue light.
2. RGB Color Chart Test
1. Prepare an RGB color chart as follows.
2. Wear your blue light block glasses and look at the chart.
3. After wearing blue light blocking glasses, if the B section becomes black and the G section becomes darken, it shows that your blue light glasses block blue light and some filter some green light.
4. The less bright the green circle with your blue light glasses, the better they are.
Besides the above ways, you can ask the professional optician to perform a professional blue light glasses test, which would be more reliable. After that, you can know whether your glasses work effectively to block blue light.
What’s more, if you want to purchase a pair of effective blue light blocking glasses, you can try Koalaeye Optical. It is cheap and provides free shipping services.
Each pair of glasses has its own size.
People began to shop for myopia glasses online, but because of lack of experience, many times the size of glasses is not appropriate. At this time they used to complain about the business or glasses. It is really because that they do not see the size of the frame. Just like our clothes and shoes, each qualified frame has its own size. Usually, the size will be marked on the inside of the temple or the bridge of the nose. The manufacturer will clearly mark the width of the frame, the width of the bridge of the nose, and the arm length of the glasses.
Disadvantages of bifocal glasses
The disadvantage of bifocal glasses is that the different areas are clearly spaced and the appearance is not beautiful. The medium distance is fuzzy, and the adaptation period is needed, there is a prismatic jumping phenomenon. The focal distance between the upper and lower lenses is different, with a clear dividing line. The main disadvantage is that when the line of sight moves from far to near, there will be interference like jumping, and the middle distance object image is blurred. Students can adapt to sitting still in a class by wearing bifocal glasses, but they can only wear glasses when they are in class or studying because of the inconvenience and even danger caused by the interruption of the glasses.
When were the first glasses invented?
No one knows when the first pair of glasses were invented, but we do know that the grinding techniques for making simple magnifying glasses have been around since 1000 AD, especially in regions where glasses were already produced (including northern Italy). The earliest artwork of glasses appears in the Treviso Cathedral fresco painted by Tommaso de Modena in 1352. There is reliable evidence that eyeglasses were invented in Italy in the late 13th century. The first pair we think of as eyeglasses appeared in Italian pizza in the late 12th century and looked more like two small magnifying glasses (made of raised glass) riveted together at the top of the handle. In 1266, The English Franciscan Monk Roger Bacon wrote about the scientific principles of corrective lenses, but there is no evidence that he applied this knowledge to the manufacture of eyeglasses.
Do all glasses come with nose pads?
The glasses without the nose brace are plate glasses. In reality, there is still a nose pad, but it is relatively small and it's part of the frame. The westerners have high nose bridges, and many glasses have no or very small nose pads. For example, Harry Potter's glasses have no nose pads. European and American brands will change their nose pads for the Asian market. Eyeglasses without a nose pad rely on the bridge of the nose to support the center beam. It's hard for Asians to stand up, and their eyes are more protruding than sunken like westerners. Glasses are usually demanded to keep a 12mm distance between the lens and the eyeball, otherwise, the optical performance will have a great impact.
