Certified Paraoptometric (CPO) Practice Exam 2025

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Prepare for the Certified Paraoptometric Exam with our comprehensive quiz featuring multiple-choice questions. Each question is accompanied by hints and explanations, helping you build your knowledge and confidence. Get ready to excel in your career!

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What is a planocylindrical lens?

A lens with power only in one meridian
A lens with no power in one part
A lens that combines spherical and cylindrical powers
A lens that provides equal power in all directions

The correct answer is: A lens with no power in one part

A planocylindrical lens is primarily characterized by having power in only one meridian, effectively acting as a cylindrical lens. This specific type of lens does not possess any power in the perpendicular axis, which means that it corrects astigmatism by focusing light differently along the two primary axes. Therefore, the correct answer highlights the nature of the lens’s functionality effectively. Option B suggests that there is no power in one part, which aligns with the definition of a planocylindrical lens since it operates with power limited to one direction. However, it is more correctly described as a lens with power only in one meridian, concentrating its power in a single direction while lacking it orthogonally. This distinction ensures that the lens addresses astigmatic errors effectively by altering the focal plane along the axis where it does provide power. The other options either mischaracterize the attributes or functions of a planocylindrical lens, leading to an inaccurate understanding of how it operates within the field of optometry.