Finishing – after the contact lens has been created, either by moulding or lathing, the lens requires more specific curvature to be created for it fit comfortably on the wearer’s eye. As with the polishing part of the lathing process when creating the contact lens, the contact lens is placed upon an arbor where small slices are taken, followed by precise smooth finishing with emery paper.

Quality Control – further to the contact lens being created and finished, each contact lens must pass through a rigorous Quality Control procedure. This is carried out throughout the manufacturing process and once again at the end, by two separate procedures. Firstly, the contact lenses are viewed under a microscope to see any obvious problems. Secondly, a shadowgraph is created of the contact lens, which shows any issues with the contact lenses on a greater scale for easier viewing. Whilst some differences between contact lenses may be not be problematic (mainly for cosmetic contact lenses), if the contact lenses are custom made, it is extremely important that any issue or problem with the contact lens is discovered and amended before it is ready to be sold.

Packaging – before the contact lenses can be delivered to the store or pharmacy, they must be packaged to a certain standard. Generally, contact lenses are first boiled for hours and packaged in sterile material, with a saline solution. Once this process has taken place, the contact lenses are ready to be delivered and worn.

• How Contact Lenses Are Made – Part 1

When contact lenses are being created, there are two initial ways to create the contact lens – the moulding method and the lathing method. Both have their own benefits and both are still used to create contact lenses today.

Moulding – when contact lenses were first being produced by the moulding procedure, they were initially created by pouring a mixture of fluids into a rotating mould. The contact lens shape was created by both the mould itself and by how fast the mould was rotating.

Over the years, injection moulding was introduced, which is a much more reliable and easier means of creating contact lenses by moulding. In essence, the fluids are injected into a pressure mould at a high temperature, quickly removed and allowed to cool, with finishing taking place on a lathe. Extremely effective in creating high quality contact lenses in mass quantities, injection moulding has only been in use in recent years.

Lathing – A longer, but more finished process of creating contact lenses is by using a lathe for the full process. The contact lens material is mounted upon a lathe, which turns at a set speed and angle, allowing for the cutting tool to carry out its work and effectively make the actual contact lens. After the process, the lens is placed upon a separate machine where it is polished and coated to ensure no rough or uneven edges and to give it a safe finish.

• How Contact Lenses Are Made – Part 2