ABO NOCE Practice Test 2026 - Free Optician Certification Practice Questions and Study Guide

A minus lens is characterized as a concave lens. This type of lens is thinner at the center than at the edges and is used to diverge light rays that pass through it. When light enters a concave lens, it causes the light rays to spread apart, which creates a virtual image that appears closer than the actual object. This is particularly beneficial for individuals who are myopic, or nearsighted, as it helps them to see distant objects more clearly.

In contrast, a convex lens, which is thicker in the center than at the edges, converges light rays and is used to correct hyperopia, or farsightedness. Cylindrical lenses are designed to correct astigmatism by having different powers in different meridians, while spherical lenses have the same power throughout. Each of these lens types serves distinct purposes in vision correction, highlighting the unique role of concave lenses (minus lenses) in addressing specific visual impairments.