The process of measuring the curvature of the cornea (keratometry) and the length of the eyeball and using these data to determine the power of an ideal non-contact intraocular lens. The IOL master is a non-contact instrument used to measure several parameters such as axial length of the eyeball, curvature of the cornea, depth of the anterior chamber, white-to-white horizontal distance (corneal diameter), and calculating the power of the intraocular lens. This examination is done before cataract surgery.

(source : www.doktermata.co.id)