The base curve is abbreviated as BC, which is one of the important parameters of contact lenses, which represents the size of the curvature of the contact lens. The larger the value, the flatter the inner surface of the lens, and the smaller the base curve, the more curved the inner surface of the lens.
When the base curve of the contact lens is larger than the base curve of the eyeball, the lens cannot be attached to the eyeball well, and the phenomenon of displacement is likely to occur, causing problems such as unstable vision. And if the base curve of the lens is smaller than the base curve of the eyeball, the lens will be tightly attached to the eyeball, and the eye will be more prone to hypoxia and fatigue than usual, and neovascularization may occur, which affects eye health.
The base arc of Chinese is mostly between 8.4-8.6, but there are a few higher or lower than this range. If you feel uncomfortable when changing to several brands of products, it may be due to the special base curve of your eyeball. Generally speaking, it is normal for the difference between the base curve of the lens and the base curve of the eyeball to be within 0.2mm, but if you find that there is no suitable base curve, remember to choose the big one and not the small one.
When fitting glasses, measuring the radius of curvature of the cornea is a very critical step, which determines the subsequent wearing comfort, but many optical shops may ignore this step. If you have doubts about the lens you are wearing, you can check it yourself. When you push the lens with your finger, you can only partially push it away, indicating that the base curve is just right.
For contact lens wearers, the choice of parameters is very important. A well-fitted contact lens can ensure stable vision and clear vision. If the lens parameters are not suitable, it is easy to cause various ocular discomforts such as corneal hypoxia, asthenopia, and severe corneal damage.