Materials and Performance of Soft Contact Lenses š§
ā¢Posted on August 21 2024
Contact lensesĀ are made from various materials, and these materials can significantly affect comfort and performance. Today, let's explore the key materials used in soft contact lenses and their characteristics!
Basic Materials of Soft Contact Lenses š§¬
Soft contact lenses are made from polymers that incorporate water. These polymers are created by cross-linking various monomers. In addition to polymacon, other materials used in soft contact lenses often have the suffix "filcon." The U.S. Food and Drug Administration (FDA) categorizes soft contact lens materials into four groups based on a 50%Ā water content.
- Group 1 (Low Water Nonionic Polymers): These have low water content and are less likely to accumulate proteins on their surface. Common materials include crofilcon (38%, 12) and hefilcon A&B (45%, 12).
- Group 2 (High Water Nonionic Polymers): These contain higher water content, allowing for more moisture. Materials like hefilcon C and lidofilcon A (70%, 31) are typical examples.
- Group 3 (Low Water Ionic Polymers): These are ionic and have low water content. An example is bufilcon A (45%, 12).
- Group 4 (High Water Ionic Polymers): These are ionic and have high water content. Notable materials include bufilcon A (55%, 16) and etaifilcon A (58%, 28).
What is HEMA? š¤
One of the most commonly used materials in soft contact lenses isĀ HEMAĀ (2-hydroxy-ethyl methacrylate). This material is highly stable across various conditions such as temperature, pH, and osmotic pressure. The basic water content of HEMA is 38%, and it can vary depending on what monomers it is combined with.
- Hydrophobic Monomers: When combined with materials like methylmethacrylate (MMA) or styrene, the water content decreases.
- Hydrophilic Monomers: When combined with materials like N-vinyl pyrrolidone (NVP) or methacrylic acid (MAA), the water content increases.
Tip: Many of Klenspop's products are made using HEMA, which provides excellent moisture retention and comfort for extended wear. If you're looking for comfortable colored lenses, explore Klenspop Colored Contacts to find a style that suits you!
Comparison with Other Polymers š
Similar to HEMA, glycerol methacrylate (GMA) is another material often used in contact lenses. GMA-based materials are known for their resistance to deposits on the lens surface, making them easier to maintain.
