Which method is most effective for reducing lens thickness?

The most effective method for reducing lens thickness is indeed the option related to smaller, rounder lens shape. This approach works because the curvature of the lens directly influences the optical properties and the amount of material required to achieve the desired prescription. A smaller lens shape means that less surface area needs to be covered with lens material, which leads to a reduction in overall thickness.

When lenses are rounder and smaller, there is less distance from the center to the edges, which minimizes the volume of material used for the lens. This is especially important for high prescription powers, where thickness can significantly impact the overall weight and appearance of the eyewear. By choosing a shape that is both smaller and rounder, the lens can also maintain its optical quality while managing thickness effectively.

In contrast, using a thinner material, while beneficial, only addresses the material itself rather than the lens design aspect, which is critical for thickness reduction. Increasing prescription power generally leads to thicker lenses as more curvature and material are needed. Adjusting the frame size may have some effect, but optimizing the lens shape provides a more direct and significant impact on the overall thickness.