The IOL is made with precise power based on the position of the lens, the curvature of the cornea, and the length of the eye. Each of these measurements is taken prior to surgery and may be checked again during surgery, when adjustments can be made. Your intraocular lens is designed to work very much like your natural lens or prescription eyeglasses or contacts. As light passes through the front of the eye, it bends based on the power of the IOL. This focuses rays of light to land accurately on the retina at the back of the eye. The accuracy of the rays of light supports crisp, clear vision at multiple distances.