Mandell-Moore Calculation: BC Flat
• If Cyl < 2.50D → BC = K
• If Cyl ≥ 2.50D → BC = K - 0.25D BC Steep
• If Cyl < 3.00D → BC = Ksteep - 0.50D
• If Cyl ≥ 3.00D → BC = Ksteep - 0.75D
Clarity Plus Multifocal
Standard center-distance multifocal
If Cyl < 2.0D, BC=K + 1.00D If Cyl > 2.0D, BC = K + 1.25D
Clarity Plus Extended Add Multifocal
Higher add for greater near demand
If Cyl < 2.0D, BC = K + 1.50D If Cyl > 2.0D, BC = K + 1.75D