Certified Paraoptometric (CPO) Practice Exam 2025

What type of lens would best correct astigmatism?

1. Spherical lenses

2. Multi-focal lenses

3. Planocylindrical lenses

4. Bifocal lenses

The correct answer is: Planocylindrical lenses

The correct answer is indeed planocylindrical lenses, which are specifically designed to correct astigmatism. Astigmatism occurs when the cornea or lens of the eye is irregularly shaped, causing light to focus unevenly on the retina. Planocylindrical lenses have a cylindrical component that helps in addressing the specific curvature of the cornea. This cylindrical power effectively counteracts the irregularity, allowing for proper focusing of light and improving vision clarity. In contrast, spherical lenses are uniform in shape and primarily correct nearsightedness or farsightedness but are not effective for astigmatism since they do not account for the different curvatures present in the eye. Multifocal lenses, which are designed to help with presbyopia by providing multiple optical powers, do not directly address the specific needs of astigmatism. Bifocal lenses, while useful for individuals needing correction for both distance and near vision, similarly do not provide the customized correction needed to manage astigmatism effectively. Therefore, planocylindrical lenses are the optimal choice for correcting astigmatism specifically.