SRK1

SKR1 formula: P = A – 0.9 K – 2.5 * L

SRK2

SRK2 formula is similar to SRK1, but provides the following adjustments to the A constant for very long or short eyes:

• L<20.00mm: add 3 to A constant
• L between 20.00mm and 20.99mm: add 2 to the A constant
• L between 21.00mm and 21.99mm: add 1 to the A constant
• L>24.50mm: subtract 0.5 from the A constant