What does a power cross depict in lens manufacturing?

The power cross is a graphical representation that illustrates the power of a lens in two principal meridians, which are typically oriented at 90 degrees to each other. This concept is essential in understanding how cylindrical lenses work, as it helps to determine the amount of correction needed for astigmatism by showing the power in the horizontal and vertical directions.

In lens manufacturing, it's crucial to understand the orientation and magnitude of power for both meridians since this information directly affects how the lens corrects vision. The power cross visually indicates the strength of the lens in each meridian and allows opticians to quantify and visualize how the lens will bend light, enabling precise fitting and customization.

The other options, while relevant in different contexts of optics, do not describe the function of the power cross specifically. The lens thickness refers to the physical size of the lens, the focal point pertains to where light converges or diverges, and edge configuration relates to the shape of the lens edges, none of which are part of the power cross’s purpose.