Certified Paraoptometric Practice Test

These lenses are thin in the center and thick on the edges. Objects viewed through these lenses will appear smaller or minified. Light rays passing through these lenses will be diverged. What type of lenses are these?

1. Astigmatism lenses

2. Concave lenses

3. Plano lenses

4. Prism lenses

The correct answer is: Concave lenses

The described lenses are known as concave lenses. These lenses are characterized by their construction, where they are thinner in the center and thicker at the edges. As a result of this design, concave lenses diverge light rays that pass through them. When light rays diverge, they spread apart rather than converge to a point, leading to a visual effect where objects viewed through these lenses appear smaller or minified. This minification occurs because the image formed by a concave lens is reduced in size compared to the object. In optics, concave lenses are commonly used in situations where corrective vision is needed for individuals who are nearsighted (myopic). By diverging the light rays before they reach the eye, the lens helps focus the image properly on the retina, allowing for clearer vision at a distance. The incorrect options refer to different types of lenses that serve various functions but do not match the characteristics outlined in the question. Astigmatism lenses are designed to correct for astigmatism by having differing power in different meridians, plano lenses are flat and do not alter the path of incoming light, and prism lenses shift the light pathway to correct alignment issues without the minifying effect described.