To correct vision you worn a device known as a contact lens, sometimes people wear colored contact lenses to enhance or change their eye color. Many people prefer contact lenses over glasses for cosmetic reasons, an active sports enthusiasts prefer contact lens because of the freedom it provides them.
Contact lens is portable, lightweight that can be applied directly to the eyes to correct visual defects. There are two main types of contact lenses in today's market, soft contact lens made from hydrogen and the rigid contact lens that is not flexible. As innovation in materials grew, so did efforts to enhance manufacturing processes. Different manufactures developed an assortment of technologies to allow for today’s high production rates of quality lenses this article aims to summarise the technique of Manufacturing contact lenses.
1: Spin casting – In this method, monomer liquid is injected into a spinning mold. Heat or UV light is used to initiate polymerization. This method uses centrifugal force to form the shape of the base curve while the shape of the front curve is created by the mold. After being taken from the mold, lenses needed to be hydrated before packaging. Overall, this process has high throughput and lower manual costs.
2: Cast molding – This method is used to manufacture some brands of soft contact lenses. In the cast molding technology of silicone hydrogel lenses, the silicon hydrogen materials precisely replicate the mold surface. In this method, monomers are mixed and poured into a mold at a tightly controlled temperature. Lens material is heated or curved to produce a mobile phase. The polymerization is initiated by ultraviolet light as the mold travels along the production line and the lens hardens.
3: Lathe cutting – During this process, the anhydrous polymer is firstly got two small buttons with the required diameter. Then the first surface of the lens is cut by the lathe tool to the required curvature. For this after one side is complete, the button is transferred to another lathe to cut the other surface. Both sides are carefully polished to remove any age before it is soaked in saline solutions to hide with the lens.
4: Injection molding – In this process, the soft contact lenses material is heated to a molten state and is then injected into computer-designed molds under pressure. The lenses are then quickly cooled and removed from the molds. The edges of the lenses are polished smooth, and the lenses are hydrated to soft in them prior to undergoing quality assurance testing.
With the help of technology transfer, future materials with electronic properties provide better vision, help monitor and treat health conditions and even deliver an interactive visual experience.