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The Manufacturing Process for Soft Contact Lenses

Tue 4th Aug 2009 - 8:18 am - Back to Article Selection

How soft contact lenses are made

Contact lenses are made through a complicated and unique process. There are several different ways to make the lens, and each method yields slightly different results. Each manufacturing brand uses one of the following two methods to construct their disposable contact lenses. This method can be through moulding or cutting the lens. Sometimes the manufacturing process will determine if the lenses will be cheap contact lenses or if they will be expensive. Different brands also have different price levels based on brand recognition and perceived value. Some popular soft lens brands are: Acuvue, Focus Dailies, Biomedics and Soflens. There are many other soft lens brands as well.

First lenses

The first contact lenses were created in 1887. These early contact lenses were made of glass, and were shaped to fit over the eye. These contacts were extremely heavy and bulky, and they irritated the eyes of whoever wore them. The first plastic lenses were created in 1938. They were made of Plexiglas. People enjoyed these contact lenses much more because they were lighter and less bulky. However, by today’s standards they would appear irritable and bulky. 1952 was the first year that soft plastic was made for contact lenses. The scientists wanted to create a plastic that allowed the absorption of water. When this plastic was discovered, they quickly started using it for vision correction. The first year that soft contact lenses were sold was in 1971.

Shaping the lens

The first part of the soft lens manufacturing process is the shaping of the plastic into a form that fits over the eye. There are two main ways in which this is done. Usually the lenses are either shaped by moulding the plastic into the proper shape, or by cutting the plastic on a lathe. Recently the moulded version of construction has been the most popular. Since the introduction of computers and laser cutting techniques the process of creating contact lenses has changed somewhat. However, the basic principles remain the same.

Moulding

Some soft lenses are created by moulding the lens. Different kinds of plastic are poured into the mould and then the moulds are rotated. The spin of the moulds causes the plastic to shape itself into the necessary shape inside the mould. Another way to mould lenses is to inject the melted plastic into the mould so that it stays in the proper shape. More recently it has been possible to mould the perfect shape of lenses with computer controlled moulding techniques.

Cutting

Another way to shape lenses is by cutting and shaping the plastic on a lathe with a knife. Usually the cuts are made with a laser, but in the past, actual knives were used. The plastic is shaped with the cutter by making concave cuts into the plastic while the lathe is spinning. The lens is then moved to another machine which polishes the plastic until it is transparent. Last of all the lens is flipped and moved to another lathe to make the final shaping cuts. Then the second side is polished smooth.

Final shaping

The last part of disposable contact lenses production is the additional cuts or polishing required for finishing the lens. The lenses have to be shaped exactly so that they will fit over the eye. These final shaping cuts are usually made on a lathe. A razor or emery paper is usually used to make these final, tiny adjustments. The introduction of laser production for contacts has made this last step unnecessary for many manufactures.

Packaging

The contact lenses next go through rigorous quality control before being packaged for sale. Usually this is done by inspecting the lenses with a microscope. The lenses are then boiled in salt water for several hours to prepare the lenses for wear. Next the lenses are packaged in a saline solution and are placed in lens boxes to be shipped out. The lenses are often placed in glass tubes with rubber stoppers. Both cheap contact lenses and more expensive ones are packaged in the same way.

Disclaimer: The author is not a medical doctor, optician, ophthalmologist or any other medical professional, this article has been compiled using a variety of internet reference sources and while every effort has been made to ensure accuracy this cannot be guaranteed. No preference for product or brand is inferred or intended and the contents of this article are not to be used in whole or in part to inform a decision regarding any aspect of contact lens use.

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