What happens if the glasses are not positioned so that the patient looks through the optical centers?

When glasses are not properly positioned, and the patient does not look through the optical centers, a prismatic effect occurs. This happens because the optical centers of the lenses are designed to align with the patient’s line of sight. If the lenses are misaligned, light passing through them can bend or refract in a way that causes images to appear displaced. This displacement leads to visual discomfort and can create the sensation of images being skewed, akin to how prisms alter light paths.

Understanding the importance of proper lens positioning is essential, as misalignment can significantly impact the overall effectiveness of the prescription. While issues like blurred vision and increased eye strain can arise from misalignment, the distinct outcome of the optical center misalignment is the prismatic effect. Therefore, this answer emphasizes the necessity of proper fitting and adjustment of eyewear for optimal visual clarity.