The calculation of the diopter power of intraocular lenses (IOL) is an essential part of the preoperative examination in cataract surgery (2) and is determined mainly by factors such as biometry, a non-invasive, fast and safe linear ultrasound technique that allows the measurement of the diameter…
Cataract surgery has evolved enormously over time and is now considered a refractive procedure, but no matter how much you master the technique of phacoemulsification, microincision and other advances, success is influenced by the correct power of the intraocular lens calculation. The most important factors of this are the biometry that measures the axial length of the eye by means of contact and immersion technique, the optical coherence tomography, the keratometry that measures the radius of curvature of the previous surface of the cornea and the theoretical and empirical formulas for the calculation of the IOL, among which of 3rd generation (SRK-T, Holladay, and Hoffer Q) are those of greater use and whose capacity of prediction depends on the correct application of the constants A, SF and ACD that differ in each formula. Knowing all this range of variables and knowing how to apply them is indispensable to achieve a good surgical result and the satisfaction of the patient’s visual result; otherwise it will determine the refractive surprise. Keywords: Ultrasound, biometry, keratometry, intraocular lens, formulas, calculation constants