A distance Rx of -3.50 -2.25 x 090 with a frame PD of 65 and a patient PD of 61 will have the majority of its thickness:

• A. Nasal
• B. Superior
• C. Temporally
• D. Inferior

Answer: (C)

The situation involves how lens thickness distributes when a frame’s distance between eyes is larger than the patient’s PD, requiring decentering of the lenses. Because frame PD is 65 and patient PD is 61, the lenses must be decentered toward the nose to align with the eyes.

For a distance Rx with axis 090, the cylinder power adds to the horizontal meridian, giving -5.75 D in the horizontal direction and -3.50 D in the vertical direction. This makes the lens inherently thicker toward the horizontal edges. When you decenter the lens nasally (to match the smaller PD), the thicker portion shifts toward the temporal edge.

So, the combination of stronger horizontal power and nasal decentration moves the bulk of the lens thickness to the temporal side.