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Lensmaker equation

The surface power of a lens = Ds = (n’- n)/r, where r is in meters, n = the index of the object space (air or fluid the lens is in) and n’ = the index of the lens. This is also called the refractive power or simply the power of a spherical refracting surface.

The power of a thin lens (IOL) immersed in fluid
D_air/D_fluid = (n_IOL – n_air)/(n_IOL – n_fluid)