What parameters should I look at when buying contact lenses? Which brand is good?

Contact lenses are very popular and there are many brands to choose from in the market. What parameters should be considered when fitting contact lenses? Which brand of contact lenses is good?

What parameters should be considered when fitting contact lenses?

The parameters we need to pay attention to when fitting contact lenses are base curve and water content. The former is related to whether the lens is suitable for the shape of your eyeball, and the latter is related to whether the lens is oxygen permeable.

1. Base curve and friction

Contact lenses are personalized products, and their diameters and base curves may vary. Everyone needs to choose according to their own eyesight. Ill-fitting contact lenses can be uncomfortable and may cause corneal abrasions. The base curve represents the radius of curvature of the contact lens and determines the curvature of the contact lens. The smaller the base curve, the larger the curvature of the lens. The base curve is an important indicator when choosing glasses. If the base curve of the glasses is smaller than the eyeball, it means that the lens is too flat, which will cause it to not stick and easily shift; if the base curve of the glasses is much larger than the eyeball, it means that the curvature of the lens is too large, and it will be very tight and uncomfortable to wear. Generally speaking, the base curve of hard contact lenses can be the same as the eyeball, while the base curve of soft contact lenses should be 10% larger than the base curve of the eyeball. The curvature indicator of the eyeball is the corneal curvature. Your corneal curvature plus 0.4~0.8 is basically the base curvature range of the contact lens that is suitable for you.

2. Water content and oxygen permeability

The cornea absorbs oxygen from the air. Contact lenses block the cornea from the air, causing the cornea to be deprived of oxygen. The longer you wear it, the more severe the hypoxia will be. When it reaches a certain extent, it will cause diseases, such as keratitis, corneal edema and so on. Therefore, the oxygen permeability of contact lenses is also very important, which determines how long this type of contact lenses can be worn. You must have heard at the contact lens counter that the higher the water content, the better the oxygen permeability. This statement is not accurate. Contact lenses have a high water content, and the cornea can absorb the oxygen in the moisture of the contact lenses to ensure a certain oxygen supply. However, in order to produce a high water content, the thickness of the contact lens must be increased, which will further block the oxygen exchange between the cornea and the air. Therefore, high water content does not necessarily lead to good oxygen permeability. In addition, water-containing contact lenses have another drawback, which is that water will evaporate in a dry environment. At this time, the contact lens will absorb moisture from the cornea and cause dry eyes. You can achieve oxygen permeability by choosing a breathable lens material, such as silicone hydrogel. The material itself has good air permeability, and with the low water content design, it can be breathable and comfortable and not easy to dry out. If I had to recommend one, I think silicone hydrogel contact lenses with a low water content would be a better choice.

What brand of contact lenses is good?

I believe that every long-term wearer has a favorite brand and model in mind, but objectively speaking, there are currently four major brands of contact lenses in the world, namely:

1. Johnson & Johnson Acuvue: A subsidiary of Johnson & Johnson, its product diversity is relatively insufficient, but it has a good reputation and a large market share. In addition, the "beauty contact lenses" that are very popular among girls have been registered by Johnson & Johnson, and refer to Johnson & Johnson's colored contact lenses.

2. Alcon/Vision Biomedical: Alcon and Vision Biomedical merged in 2013 and belong to the same parent company, Novartis Group.

3. Cooper: Very professional and focused on R&D, but its popularity in China is relatively lower than the first two.

4. Bausch and Lomb: The products are relatively low-end, and the domestic promotion is very good, so it may be the one you wear most often, but it is only ranked fourth.

Okay, that’s all the introduction about contact lens brands. I think you all understand it.