Which parameter is NOT associated with the Back Toric lens?

The parameter 'Equal ROC' is not associated with the Back Toric lens. Back Toric lenses are designed with specific characteristics to correct astigmatism and typically have a toric base curve (which differs in curvature across different meridians).

The other parameters play essential roles in the design and function of Back Toric lenses:

• The Base Curve Toric refers to the back surface of the lens having a toroidal shape to align with the patient's corneal topography. This is crucial for ensuring proper fit and visual correction.

• The Spherical Front indicates that the front surface of the lens is spherical, which is common in many lens designs and allows for consistent vision correction along the spherical meridian.

• The Cylindrical Back relates to the specific shape designed to counteract the astigmatism by providing varying power in different meridians, which is essential for achieving clear vision in individuals with astigmatism.

In contrast, 'Equal ROC' generally refers to a condition where the radius of curvature is the same across different meridians, which is not characteristic of Back Toric lenses. These lenses inherently have a different radius of curvature across their toric base to manage astigmatism, making ‘Equal ROC