What does spherical correction provide?

Spherical correction is designed to address vision problems related to myopia (nearsightedness) or hyperopia (farsightedness). It provides a single focal length correction, which means it corrects the overall refractive error by using a lens with a consistent curvature throughout. This is essential for individuals who require a straightforward adjustment to their vision.

For myopia, spherical lenses are concave (thinner at the center), which helps diverge light rays before they enter the eye, allowing clearer vision for distant objects. Conversely, for hyperopia, spherical lenses are convex (thicker at the center), converging light rays to assist with focusing on nearby objects.

Since spherical lenses have the same curvature across their entire surface, they provide just one focal length, which is suitable for correcting the primary refractive errors without addressing the complexities of conditions like astigmatism or the need for separate focal points for tasks such as reading or distance vision. Thus, the correct answer highlights the function of spherical correction effectively.