Contact Lens Materials - Non-HEMA materials
The non-HEMA materials are hydrophilic soft lens material, which does not contain HEMA components. They are stronger and more oxygen permeable than most HEMA polymers.
The water content of regular hydrogel lenses varies from 30% to 58%. When oxygen passes through the hydrogel, it needs to be carried by water molecules in the material. Therefore, the higher the water content of the lens, the higher the oxygen permeability value. The softer the lens, the more comfortable it is to wear, which is conducive to the metabolism of the cornea. However, at the same time, the higher the water content of the lens, the faster the water evaporation, easy to dehydration, and easy to cause dry eyes. A lens with high water content has low material density, poor durability, and easy breakage, so they are suitable for making lenses that are frequently changed or discarded. On the contrary, the lens with low water content has good formability, easy operation, durability, and is not easy to dehydrate and cause dry eyes.
Choose high-quality lenses.
As resin lens technology becomes more and more mature now, resin lens has gradually become popular, so the use of resin lens is the trend. Now resin coated lenses are very popular now. There are anti-reflection films and hard films (anti-wear films) anti-UV films. Anti-reflection film can improve the transmittance of light, making people see more clearly, at the same time, because it can reduce the reflection, the lens is more beautiful in appearance. Hard coating films can effectively protect the lens surface from wear and tear and can resist the damage of hard objects, to prolong the life of the lens. UV-resistant films block the harmful ultraviolet rays of sunlight. For example, the UV400 lens is good for engineers who work outdoors for a long time.
Design principle of progressive multifocal lens
For the same piece of the lens, the top is used to see far, the bottom is used to see close. The upper and lower degrees are different.
There is not a sudden change in the distance degree fixed above the lens to the near degree fixed below the lens, but a gradual transition between the two through gradual changes in refractive power, which has special benefits over common bifocals or trifocal lenses.
Features of progressive lenses
With the proper head position, the wearer can have a clear and continuous vision at all distances from the distal point to myopia through the progressive lens. When the eye moves from one area of vision to another, the eye adjustment process is natural and smooth, without any visual fluctuations. With natural vision and better adaptability, it is in line with physiological optics. The mid and near vision area is relatively small: Some wearers may feel that the gradient area of the progressive lens is smaller, which limits the width of the saccadic eye and requires increased head movement in order to achieve the same reading range. At medium and short distances, the wearer needs to coordinate certain head movements.
The fabric of eyeglasses cloth
Ordinary fabric: They are only applicable to the surface that has been cleaned.Because the ordinary fabric has no space to accommodate dirt, the surface of the cloth will be very dirty, and difficult to wash clean.
Microfiber fabrics: They are used wet to emulsify dirt and oil, and the microfiber is easier to wipe off. It is highly absorbent, making it very quick to clean the spilled liquid.
Fine fiber double velvet fabric: It feels soft, gentle, with the plump texture, but more single velvet.
Suede fabric: The feel and appearance are quite like natural suede, fine and smooth, soft and plump, used to wipe glasses. It will be clean and won't scratch the lens.
Cosmetic Contact Lenses & Chromatic Contact Lenses
We are used to referring to chromatic contact lenses as beautiful contact lenses. In fact, beautiful contact lenses are a registered trademark of Johnson & Johnson in 2007. It is the name of a product series of Johnson & Johnson. Not all chromatic contact lenses are called beautiful contact lenses. Regular contact lenses can have complications if they are not properly worn, and these can also be seen in chromatic contact lenses. But because the color piece was much a layer of pigment, if the quality is not up to standard, there will be greater safety hidden trouble.
Prepare a few pairs of glasses
Many people now have a 'reserve' of glasses. For example, you can choose two pairs of glasses. One pair is for daily use, and the style should be relatively simple and traditional. The other pair is for use at gatherings or weekends and can be as cool as you want. The more conservative style is a thin and bright metal frame that matches the shape of your face. For the other pair, you can choose a flat plastic frame or a shiny polished metal frame with a unique shape.
