How are contact lenses made ?

Exactly how are contact lenses made?
Many people wear them but few know how a contact lens is made.
Contact lenses can come in a variety of shapes, sizes and color .
The most popularly used contact eye lenses today are the soft variety.
The first soft contact lenses were developed in 1960 – but it was only in 1971 when the public had access to eye contacts.
Toric eye lenses for astigmatism were approved for use in 1978.
The first rigid gas permeable lenses were introduced in 1979.
Subsequent advances in eye wear technology saw the introduction of bifocal eye lenses, tinted eye lenses, daily wear soft lenses, and disposable contacts.
In the nineties, eye wear became even more advanced when companies started introducing disposable tinted eye lenses, and disposable contacts with UV protection.
How Are Contact Lenses Made Exactly?
In most cases, the manufacturing of lenses is automated.
Key factors companies use to determine the type of lens include 1) Total power the finished lens must have; 2) Strength and size of the segment contact lenses; 3) The strength and orientation of the lens curves; and 4)
Minute details such as the location of the optical center, and any induced prism that may be needed.
Contact eye lenses are generally categorized as hard or soft.
Hard contact lenses are manufactured from rigid material such as polymethylmethacrylate.
This sturdy material is sometimes combined with other plastics to improve oxygen permeability.
These are called rigid gas permeable lenses. Soft contact eye lenses are made from a plastic hydrogel polymer, hydroxyethylmethacrylate, which has a high water content.
Aside from being categorized as hard or soft, contact eye wear can also be identified by its longevity (extended wear, daily wear, disposable) and by its prescription type (aspheric, bifocal, toric, etc.).