What is a secondary curve?

A secondary curve is typically designed to provide additional support and stability to a contact lens, and it is often designed to be flatter than the base curve. The base curve is the primary curvature of the lens that directly conforms to the shape of the central cornea, while the secondary curve, being flatter, helps in managing the lens' fit and movement on the eye. This flatter curve assists in ensuring that the lens has appropriate alignment and comfort, allowing for tear exchange beneath the lens and minimizing the risk of edge-lift or discomfort during wear.

For effective lens design, the use of a secondary curve can be crucial in accommodating various patient needs, ensuring proper fit, and maintaining overall ocular health. The distinction in curvature between the base and secondary curves is essential for optimizing performance, comfort, and stability of the lens during wear. Thus, recognizing the characteristics of a secondary curve as usually being flatter than the base curve is important for a lens fitting and design context.