Why should you choose a small plus lens blank vs a larger plus lens blank?

• A. A larger plus lens blank will leave the final lens thicker
• B. A larger plus blank reduces edge thickness
• C. A smaller blank increases cost
• D. A larger blank improves optical performance

Answer: (A)

In plus lenses, the thickness is concentrated at the center. The final center thickness is largely set by the stock blank’s center thickness, and edging primarily removes material from the outer periphery to achieve the required frame size. So a larger blank brings more material into the center into the finished lens, making it thicker. Using the smallest blank that still provides the needed optical zone and frame fit minimizes that central material and yields a thinner lens. The other ideas don’t fit because blank size doesn’t reliably reduce edge thickness, it doesn’t inherently raise or lower cost in a way that matters here, and it doesn’t improve optical performance—the power comes from the lens’ curvature, not the blank’s diameter.