What type of material is commonly used in high-index lenses?

High-index lenses are designed to be thinner and lighter than standard lenses, which makes them an ideal choice for individuals with strong prescriptions. The commonly used materials for these lenses include polycarbonate and high-index plastics.

Polycarbonate is a durable and lightweight material that offers impact resistance, making it an excellent choice for eyewear, especially for children or active adults. High-index plastics, on the other hand, have a higher refractive index, allowing them to bend light more efficiently. This means that lenses made from these materials can be made thinner while still providing the necessary corrective power.

The other materials mentioned in the question do not meet the criteria for high-index lenses. Glass, while it can be used for lenses, is generally heavier and thicker compared to modern high-index materials. Regular plastics also do not provide the same level of thickness reduction for stronger prescriptions as high-index options do. Wood is not a suitable material for eyewear lenses due to its inherent properties, such as weight and lack of optical clarity.

By using advanced materials like polycarbonate and high-index plastics, high-index lenses can offer improved comfort and aesthetics for those who need stronger vision correction.