When choosing a frame for a wearer of PAL's, what is the most important factor to consider?

When selecting a frame for a wearer of progressive addition lenses (PALs), the most important factor to consider is providing sufficient vertical depth. This is crucial because PALs have different zones for near, intermediate, and distance vision that are arranged vertically in the lens. The vertical depth of the frame affects how well these zones align with the user's eyes when they look through the lenses.

If the frame does not have enough vertical depth, it can limit access to the progressive areas of the lens, potentially leading to blurred vision or a narrow field of view in the various zones needed for everyday tasks. A frame with adequate vertical depth ensures that the wearer can utilize the full functionality of the PALs, allowing seamless transitions between different vision zones.

The narrow "B" measurement or insufficient horizontal depth may accommodate certain aesthetic preferences or specific face shapes, but these factors do not significantly affect the overall effectiveness of PAL performance as much as vertical depth does. A frame with a wide bridge measurement primarily addresses fit comfort and stability rather than functionality related to lens performance. Therefore, prioritizing vertical depth is key for maximizing the visual experience in progressive lenses.