Which statement is true about Dk and CT in diagnostic fitting sets?

Which statement is true about Dk and CT in diagnostic fitting sets?

• A. Dk is low and CTs are all the same
• B. Dk is high and CTs vary
• C. Dk varies and CTs vary
• D. Dk is medium and CTs are all the same

Answer: (A)

Diagnostic fitting sets are built to let you judge how a lens sits on the eye based on geometry, not on how much oxygen the material can deliver or on thickness differences. To keep the assessment focused on fit, the set uses lenses with the same center thickness so sag, vault, and edge behavior are driven by base curve and overall design rather than thickness. Using a material with relatively low Dk further minimizes variations in corneal response between lenses in the set, so differences you observe are mainly due to shape rather than oxygen supply. That’s why a low Dk and identical center thickness across the set is the true setup described. If Dk varied or center thickness varied, you’d be mixing material properties and thickness into the comparison, making it harder to isolate fitting characteristics.

Diagnostic fitting sets are built to let you judge how a lens sits on the eye based on geometry, not on how much oxygen the material can deliver or on thickness differences. To keep the assessment focused on fit, the set uses lenses with the same center thickness so sag, vault, and edge behavior are driven by base curve and overall design rather than thickness. Using a material with relatively low Dk further minimizes variations in corneal response between lenses in the set, so differences you observe are mainly due to shape rather than oxygen supply. That’s why a low Dk and identical center thickness across the set is the true setup described. If Dk varied or center thickness varied, you’d be mixing material properties and thickness into the comparison, making it harder to isolate fitting characteristics.