Question

How many curves are in the new Ortho-K design? What are they?

a) One curve - Base curve
b) Two curves - Base curve and alignment curve
c) Three curves - Base curve, reverse curve, and alignment curve
d) Four curves - Base curve, reverse curve, alignment curve, and landing zone curve

Answer 1

The new Ortho-K design includes four curves: the base curve, reverse curve, alignment curve, and landing zone curve, which together provide refractive correction, comfort, and proper lens fitting.

Step-by-step explanation:

The new Ortho-K (orthokeratology) lens design includes four curves. These curves are:

1. Base curve - This is the central curve of the lens that primarily focuses on refractive correction.
2. Reverse curve - This curve is designed to create a space between the cornea and the back surface of the lens to facilitate tear exchange and corneal reshaping.
3. Alignment curve - It's intended to align the lens to the peripheral cornea to ensure proper centration and comfort.
4. Landing zone curve - Also known as the peripheral curve, it transitions to the sclera and helps with the distribution of lens bearing, thus aiding in lens stabilization and comfort.

Therefore, the correct answer is d) Four curves - Base curve, reverse curve, alignment curve, and landing zone curve.