Manufacture of contact lenses
There are different manufacturing systems according to contact lens materials.
For soft contact lenses:
Lathing: consists of placing a disc of the contact lens material, in a non-hydrated state, on a axis that is rotated. Then, cutting tools, controlled by computer, cut the anterior and posterior surface. Then, the finished lenses are removed to pass to a process of hydration and subsequent quality control.
Modeling by injection: the material of soft contact lenses is heated to a melted state and then injected into a mold. Then it is cooled quickly, then removed from the molds, hydrated and finally, the quality control is performed.
The manufacture by injection molding has allowed the market to use the lenses of use and throw, because the costs of manufacturing are lower.
For semi-rigid contact lenses:
Lathing: the manufacture must be very accurate because these lenses are rigid and any wrong parameter can make a failed adaptation.