Certified Paraoptometric (CPO) Practice Exam 2025

What lens type is primarily used for treating a combination of myopia or hyperopia and astigmatism?

1. Single vision lenses

2. Spherical lenses

3. Planocylindrical lenses

4. Spherocylindrical lenses

The correct answer is: Spherocylindrical lenses

The correct answer is spherocylindrical lenses. These lenses are specifically designed to correct vision problems associated with myopia (nearsightedness), hyperopia (farsightedness), and astigmatism simultaneously. Spherocylindrical lenses incorporate both spherical and cylindrical optics in a single lens. The spherical component addresses refractive errors such as myopia and hyperopia, while the cylindrical component corrects astigmatism by compensating for the uneven curvature of the cornea or lens. This dual-functionality is essential for providing comprehensive visual correction for patients who experience these combined refractive errors. In contrast, single vision lenses would only correct one type of refractive error at a time, whether it's myopia or hyperopia, but not astigmatism. Spherical lenses are designed solely for correcting either myopia or hyperopia, lacking the necessary cylindrical correction for astigmatism. Planocylindrical lenses predominantly offer cylindrical correction without the spherical aspect necessary to address all three conditions at once. Thus, spherocylindrical lenses are the optimal choice for effectively treating this combination of vision issues.