What does the "frame center" help establish during the lens fitting process?

The "frame center" plays a crucial role in ensuring that the lenses are properly aligned within the frame. This alignment is essential for achieving optimal visual performance and comfort for the wearer. By identifying the frame center, an optician can accurately position the optical center of the lenses, which is where light passes through most effectively. This alignment helps prevent issues such as distortions and visual discomfort that can occur if the optical and frame centers are not aligned.

In summary, establishing the frame center aids in the precise alignment of the lenses, ensuring that the wearer experiences an unobstructed visual pathway and optimal viewing comfort.