The outermost curve that conforms to the flatter periphery is known as

The outermost curve that conforms to the flatter periphery is known as

• A. central curve
• B. secondary/intermediate curve
• C. outer peripheral curve
• D. tertiary/peripheral curve

Answer: (D)

In gas permeable lenses, the lens is designed with multiple concentric curves to match different parts of the cornea. The central curve forms the optic zone that sits over the cornea’s steeper central area. The next curve—the secondary or intermediate curve—provides a smooth transition from the optic zone to the edge. The outermost curve is the one that sits over the flatter peripheral cornea and often guides how the lens edges interact with the lid and tear film. This outermost curve is called the tertiary or peripheral curve. The term highlights its position at the periphery and its role in fitting over the flatter peripheral cornea, helping with edge alignment and tear exchange. So, the outermost, flatter-periphery-fitting curve is the tertiary/peripheral curve.

In gas permeable lenses, the lens is designed with multiple concentric curves to match different parts of the cornea. The central curve forms the optic zone that sits over the cornea’s steeper central area. The next curve—the secondary or intermediate curve—provides a smooth transition from the optic zone to the edge. The outermost curve is the one that sits over the flatter peripheral cornea and often guides how the lens edges interact with the lid and tear film. This outermost curve is called the tertiary or peripheral curve. The term highlights its position at the periphery and its role in fitting over the flatter peripheral cornea, helping with edge alignment and tear exchange. So, the outermost, flatter-periphery-fitting curve is the tertiary/peripheral curve.