When prescribing aspheric lenses, what type of frame should you recommend?

• A. A wrap-around frame
• B. A frame with a fixed PD, regardless of patient PD
• C. A frame with large frame PD differences to improve aesthetics
• D. A frame where the frame PD closely matches the patient's PD

Answer: (D)

For aspheric lenses, precise centration is essential because the power distribution across the lens is designed to be viewed through the pupil. The frame PD determines where the optical centers sit relative to the eyes, so when the frame PD closely matches the patient’s PD, the pupil aligns with the designed optical axis and the aspheric profile works as intended. If the frame PD is off, decentration shifts the aspheric zones away from the pupil, causing unwanted prism and off-axis aberrations that reduce peripheral clarity and can induce eye strain. Other frame choices can complicate alignment: a wrap-around frame changes the tilt and effective decentration, a frame with a fixed PD ignores individual variations, and a large PD difference leads to significant decentration and distortions. Matching the frame PD to the patient’s PD preserves the benefits of the aspheric design by keeping the lens centered correctly.