Wolfram|Alpha has ophthalmology calculators. Solve problems related to the corrective lens equation for farsightedness or nearsightedness, optical power, pantoscopic tilt, radiant vs. luminous flux, radiant flux vs. luminous intensity, irradiance vs. illuminance, irradiance vs. luminance, the spherical equivalent, the probability of glaucoma, Prentice's rule, prism diopter calculations and pupillary distance.
