With the improvement in quality of life and the need for various social occasions, as well as the requirement for aesthetic convenience, colour contact lenses are gradually becoming one of the beauty products that people buy on a daily basis. However, whether you truly understand colour contact lenses and whether you can choose the right product for you is exactly what the growing consumer base needs to consider practically when purchasing.
The Development of Colour Contact Lenses
Since the 16th century, when Leonardo da Vinci proposed the idea, color contact lenses have had a history of more than 400 years, from the initial demand for convenience and simplicity; to later hygiene and comfort; to later fashion and beauty. It is no longer just a substitute for frames on specific occasions but has become a new product for vision correction, beauty, and fashion.
The reason contact lenses were introduced was because of the inconvenience of heavy frames when playing sports or attending social functions. But the early contact lenses were a temporary substitute to be worn as a last resort. At that time, the immaturity of science and technology made it possible for consumers to experience eye discomfort and other adverse effects within a few hours of wearing contact lenses.
Later, after discovering their unparalleled characteristics, people worked to develop products that were more comfortable and could be worn for longer periods of time.
During this period, hygiene and comfort became the criteria for purchase, and a boom in contact lens wear was created.
Eventually, businesses realized the potential market for contact lenses and developed other features: aesthetics. A variety of colored lenses were created, making the trendy young generation its fans.
In fact, in a modern world of rapid change and increased stress, people have higher expectations for their health. The damage of contact lenses to the cornea is gradually surfacing and becoming a growing concern for wearers. Our cornea has no blood vessels and therefore needs to absorb oxygen from the air to maintain cellular physiological activity. Lenses that come into direct contact with the cornea need to have good oxygen permeability. The discovery of this issue also left contact lens manufacturers with a technical challenge.
Selection of Colour Contact Lenses
The material of colour contact lenses commonly used in the market is a hydrogel, which is a gel with water as the dispersion medium.
- This is a polymer network system, soft in nature, can maintain a certain shape and can absorb a large amount of water.
- This material can rely on its own characteristics to replenish water and oxygen dissolved in water to the cornea. So the standard of water content is slowly becoming one of the criteria for people to buy glasses.
- The higher the water content is, the better it is because if you rely on water as a channel, the water contained in the lens itself will be evaporated after a long time, and the super absorbent performance of the lens will absorb moisture in the tear fluid, which is an essential cause of dryness in the eyes.
(2) Silicone hydrogel
There are also new colour contact lenses on the market that have advanced technology and are made of silicone hydrogel. The addition of chemical elements such as silicon and fluorine to the hydrogel has made a qualitative change in their ability to permeate oxygen.
First, the special elements allow for a smoother flow of oxygen in and out.
Secondly, the special mesh material structure forms a dual channel for oxygen and water, allowing oxygen to reach the cornea directly.
In addition, silicone hydrogel material has been found by researchers to be a better choice for healthy colour contact lenses, as it not only corrects vision, but is also easy and comfortable to wear, and has a lower chance of inducing eye disease.
2. Oxygen permeability
After understanding the categories of contact lens materials, what criteria should we use to measure their merits among similar products? Now there is a more scientific and direct reference standard: oxygen permeability (DK/T), which is the amount of oxygen per unit thickness of the lens. Oxygen permeability has now become a popular international standard for measuring colour contact lenses.
(1) Conventional hydrogel lenses: their oxygen permeability is generally around 30, while silicone hydrogel, as a new material, is several times more advanced than conventional lenses in terms of oxygen permeability.
(2) Freshlady’s colour contact lenses have passed CE and ISO international certification and can be worn continuously for 30 days as a safe contact lens.
(3) We should note that there are several groups of people who should pay special attention to the use of products with high oxygen permeability, including people who often wear makeup; people who attend various social venues; people who spend a lot of time facing computers and various monitors; people who spend a lot of time outdoors and engage in sports; people who have a rich nightlife, etc.
As a special reminder, if you are going to wear colour contact lenses overnight, then we recommend that you choose products made of silicone hydrogel with an oxygen permeability of 125 or higher, as hydrogel lenses cannot be worn overnight.
3. Base arc
The radius of curvature of the optical center of the inner surface of the lens is called the base arc in mm, and the longer the base arc, the flatter the curved surface of the lens; the shorter the base arc, the curved surface of the lens. So how should we choose the right base arc for our eyes?
(1) If you are wearing colour contact lenses, first determine if the product you are wearing is comfortable. If it is comfortable, then just check the BC parameters on the bottle, or look up the base arc of the brand you use, and then buy the same or close to the base arc of the lens, if it is not comfortable to wear, too tight means your original lens BC parameters are too small, too loose means the original BC parameters are too large.
(2) If you have never worn colour contact lenses, then you can go to a large optical store to measure, too much trouble, it is recommended to choose 8.6mm, for most people, 8.4-8.6mm base arc lenses can be better adapted; relatively speaking, the 8.6mm adaptation range to a wider range. Because in general, the lenses are a little loose and do not affect comfort, while a little tighter is easy to produce eye soreness, but of course, in the case of small differences, the eyes can adapt quickly after 1 or 2 days of wearing.