Final answer:
The original Ortho-K lens design typically had one or two curves to modify the cornea's shape for vision correction.
Step-by-step explanation:
The old/original lens design of Ortho-K, which is short for orthokeratology, typically involved a single curve or a bicurve (two curves) on the contact lens. The purpose of these curves was to reshape the cornea temporarily to correct refractive errors such as myopia (nearsightedness). Over time, lens designs have evolved significantly to include multiple curves to improve the fit and the effectiveness of the treatment. The Keratometer, a device mentioned in the reference information, measures the cornea's curvature to help in fitting these lenses accurately.