Certified Ophthalmic Medical Technologist (COMT) Practice Exam

In regular mixed astigmatism, what is true about the cylindrical power compared to the spherical power?

1. The cylindrical power is less than the spherical power

2. The cylindrical power is the same as the spherical power

3. The cylindrical power is greater than the spherical power and of the same sign

4. The cylindrical power is greater than the spherical power and of opposite sign

The correct answer is: The cylindrical power is greater than the spherical power and of opposite sign

In regular mixed astigmatism, the cylindrical power is indeed greater than the spherical power and exhibits an opposite sign. This condition involves one meridian having a positive spherical power while the other meridian has a negative cylindrical power. In essence, the spherical component addresses the overall refractive error of the eye, while the cylindrical component corrects for the astigmatism by providing additional power at a specific angle to fully compensate for the unequal curvatures of the cornea or lens. Therefore, the presence of different signs reflects the nature of astigmatism, where one meridian is more powerful (often representing the cylindrical power) while the other corrects for the overall vision. This relationship is characteristic of mixed astigmatism, which requires careful assessment to ensure that both components work in tandem to provide a well-rounded correction for the individual’s vision.