Is an optical device that measures the distance from the corneal vertex to the retinal pigment epithelium by means of partial coherence interferometry; the IOL Master is consistently accurate to within ±0.02 mm or better.The IOL Master allows fast, accurate measurements of the eye length and surface curvature, a data that is required by the modern formulas which are used for calculating the focusing capability of intraocular lens implanted during cataract surgery. This device represents a fivefold increase in accuracy, when compared to ultrasonic biometers.