Certified Ophthalmic Assistant Practice Exam

What is the common use of addition in a bifocal prescription?

1. To correct distance vision

2. To enhance near vision

3. To reduce astigmatism

4. To balance lens weight

The correct answer is: To enhance near vision

The common use of addition in a bifocal prescription is to enhance near vision. Bifocal lenses are designed to accommodate two different visual needs—distance and near vision. The addition refers specifically to the power that is added to the lower part of the lens, allowing individuals to clearly see objects up close, such as when reading or performing close-up tasks. While distance vision correction is important in bifocal prescriptions, it is not the purpose of the addition. The addition is specifically intended for helping with close-up visibility, which is why enhancing near vision is the central function of this aspect of the lens design. Similarly, astigmatism is typically corrected with cylindrical lenses, and balancing lens weight does not pertain to the optical function of bifocals but rather to the physical attributes of the lenses. Hence, the focus of the addition is directly associated with improving near vision.