Incisional corneal refractive procedures like radial and astigmatic keratotomy are being used since 1980s. Intraocular lens (IOL) calculations are important in the cataract surgery. The theoretical formulas and the statistical formulas are used to determine the IOL power in cataract surgery. Various variables required for calculating these formulas are described. Several methods to calculate the exact IOL power for the eye that had undergone surgery are explained. These are clinical history method, the Feiz-Mannis method, the Hamed method, the Aramberri double-K method, and many others. The technology and methodology used in the light adjustable lens (LAL) technology is described. The device used and the mechanism to adjust power are explained with a diagram. Various advantages, its unique features and case studies are also discussed.