Base Arc (BC) refers to the degree of curvature of the lens, expressed by the radius of curvature
The base arc radian is related to the comfort of wearing the color contact lenses, and also affects the health of the eyes
2.Size of base arc
Most of the normal eyeball base arc is 8.4 ~ 8.6mm
A few are as high as 8.8 to 8.9mm, or as low as 8.3mm
The size of the base arc is no good or bad, it is just a natural parameter of the eyeball
3.Lens base arc and eyeball base arc
The base arc of the lens is larger than the base arc of the eyeball, and there will be a sliding phenomenon that the lens cannot stick to the eyeball.
The base arc of the lens is smaller than the base arc of the eyeball, and the eyes will feel too tight and uncomfortable
The base arc of the lens cannot be completely matched with the base arc of the eyeball. Generally, the base arc of the lens should be 10% larger than the base arc of the eye.
4.How to choose base arc?
Eyeball base arc 8.4, choose 8.4~8.6 lenses, not over 8.6
Eyeball base arc 8.6, choose 8.6~8.8 lenses, not below 8.4
It is best to choose the lens base arc larger than the eyeball base arc 0.2mm.
Before buying color contact lenses, it is best to measure the base arc radian (BC) of the eyeball in an optical shop. If there’s no shop, it is recommended to choose a base arc of 8.6mm, which has the widest range of adaptability.
