If a lens rotates 10° to the right during evaluation, which parameter adjustment might be necessary?

When a lens rotates 10° to the right during evaluation, it indicates that the orientation of the lens is not aligning properly with the specified axis. This misalignment can lead to less effective vision correction, especially in toric lenses which are designed to correct astigmatism.

Lowering the axis value is a necessary adjustment because it effectively compensates for the lens rotation. The axis of a toric lens is the meridian that will have the least power, and if the lens rotates to the right (clockwise), changing the axis value downward will help re-align the lens to its intended position. This adjustment ensures that the cylindrical power aligns optimally with the eye's shape, improving vision clarity.

Other parameters like diameter, curvature, and power are not directly addressed by the lens rotation. Increasing the diameter might change the fit but does not correct the orientation issue. Changing curvature would alter the shape of the lens but again would not specifically address the axis misalignment. Adjusting power relates to the strength of the lens rather than its orientation. Thus, for a lens rotation specifically, adjusting the axis value is the most appropriate response.