IOL Master Optical Biometry versus Conventional Ultrasonic Biometry in Intraocular Lens Power Calculations in Highly Myopic versus Emmetropic Eyes

Abstract

Cataract is the leading cause of preventable blindness worldwide. Cataract extraction with implantation of an intraocular lens (IOL) is the most frequently performed ophthalmic surgical procedure worldwide. Accurate calculation of the IOL power for attaining the desired postoperative refraction remains a research issue. Several factors affect the refractive outcome after cataract surgery, including axial length, keratometry, and lens formulas. Of these factors the preoperative axial length measurement is a key determinant in the choice of intra-ocular lens (IOL) power. This study aimed to determine whether intraocular lens (IOL) power calculations for cataract surgery -as measured by postoperative refractive error- using IOL master are more accurate in improving postoperative outcomes than applanation ultrasounic biometry (AUS) in highly myopic versus emmetropic eyes. Traditionally, contact A-scan ultrasonography is used. This measures the time taken for sound to traverse the eye and converts it to a linear value (spikes) using a velocity formula. The distance between the corneal and retinal spikes gives the axial length of the eye. Keratometry reading (K1&K2) taken by manual keratometer.