Certified Paraoptometric (CPO) Practice Exam 2024

What would a lens described as 'spherical' indicate about its surface?

1. It has multiple curves

2. It is flat

3. It has a continuous curvature

4. It has varying thickness

The correct answer is: It has a continuous curvature

A lens described as 'spherical' indicates that it has a continuous curvature across its surface. This means that the lens is shaped like part of a sphere, providing a consistent radius of curvature at any point along the surface. This uniformity in shape is important for the optical properties of the lens, ensuring that light is refracted in a predictable manner, contributing to clear vision and the proper function of corrective eyewear. The concept of continuous curvature implies that the lens will focus light in a way that is characteristic of its spherical design, making it distinct from other lens shapes that may involve variations in curvature, like aspheric lenses. Understanding the spherical nature of a lens is essential for those working in optometry and opticianry, as it influences both the design and the application of different lenses in vision correction and other optical uses.