Certified Ophthalmic Assistant Practice Exam

In spectacles, why must the optical centers of lenses be properly aligned?

1. To prevent reflection

2. To improve contrast

3. To avoid prismatic effect

4. To enhance magnification

The correct answer is: To avoid prismatic effect

Properly aligning the optical centers of lenses in spectacles is necessary to avoid prismatic effect. This is because the optical center is the point where the lens is thinnest and light passes through most accurately. If the optical center is not properly aligned, the light passing through the lens will be distorted and can cause visual disturbances such as double vision or blurring. Aligning the optical centers also helps to ensure that the spectacles provide the correct level of correction for the individual's vision. So, while reflection, contrast, and magnification may also be affected by the alignment of the optical centers, it is the prismatic effect that is most directly impacted by this alignment.