How are my contacts made?

You wake up every morning and put a thin, clear material directly over your eye — and voila, the world becomes crystal clear. You no longer have to walk around scrunching your face to see the world around you. It almost feels like magic. 

If you’re here to demystify some of the magic behind contacts, you’ve come to the right place. We provide answers to questions about how contacts are made and what they're made of.  

Making contact lenses 

Contact lenses can be manufactured in various ways, including lathe cutting, spin casting, and injection molding. The exact details of how your contacts are made depend on the type of contacts you wear. Soft lenses are often mass-produced for a general fit, while hard contacts are made to fit the specific individual.  

As a result, if you wear hard contacts, your left and right eye contacts may differ even if they're produced the same way. Most people don’t have the exact same prescriptions or measurements for each eye. Turns out, we've all got a bit of Picasso in us, after all. 

Today, contacts are made of plastic polymers, but this wasn’t always the case. Contacts used to be made of glass. You heard that right; people put rigid, hard, and breakable glass in their eyes. Let's all take a moment to thank science for its advances. Contacts are a much safer and more comfortable experience today.  

The general process of manufacturing contact lenses today is as follows: 

1. The contact is designed based on prescription specifications. 

2. The lens is created from the chosen material. 

3. The lens is molded to the prescription specifications. 

4. The lens is cut into its shape using a method such as lathe cutting. 

5. The lens is polished and hydrated. 

6. The lens is inspected for imperfections and packaged.  

Method #2: Spin casting 

Spin casting is the process of injecting a liquid polymer into a spinning mold to form a soft contact lens shape. Unlike lathe cutting, which is used to make personalized shapes, spin casting is common for mass production. It can work faster and produce at a higher volume.  

The exact manufacturing process for spin casting is: 

1. A liquid monomer is injected into a curved mold that spins. 

2. The spinning motion of the mold works to spread the liquid over the mold’s surface. 

3. The spinning motion chemically changes the monomer into a solid plastic.  

4. Ultraviolet light or heat solidifies the lens.  

5. The lens is buffed to create a polished surface.  

6. The lens is hydrated by placing it in a sterile water bath. 

How are hard contact lenses made? 

Lathe cutting is used to make soft and hard contacts. As hard contacts are custom-made, the lathe cutting process is the most appropriate method (versus spin casting, which is for mass production).  

Lathe cutting is the same for soft and hard contacts. A computer-controlled lathe shapes a plastic disc of hard contact material into its shape.  

Hard contacts are also known as rigid gas-permeable lenses. These contacts are made of a more durable material, which makes them longer-lasting. The fact that “hard” and “rigid” are in the names should give you a clue about what we'll say next: Hard contacts can be uncomfortable to wear and take longer to get used to.