How many lenses are included in a diagnostic fitting set?

• A. 1-3 lenses
• B. 10-20 lenses
• C. 50-60 lenses
• D. 100 lenses

Answer: (B)

When fitting gas permeable lenses, you need enough options to test how a lens sits on the eye—its curvature, diameter, and how well it moves and centers—without having to guess too much. A diagnostic fitting set is built to provide a practical range of lenses to trial, so you can evaluate different base curves and diameters and see how they affect fit and vision.

Having only a few lenses wouldn’t cover the natural variability of corneas or show how the lens behaves on different eyes or with blinking. On the other extreme, hundreds of lenses would be unwieldy and unnecessary for most fittings. Ten to twenty lenses strikes a balance: it gives enough variation to identify a good initial fit and appropriate vision correction while remaining manageable in a clinic.

So, the typical diagnostic fitting set includes about 10–20 lenses.