Intra-ocular lens calculation status after corneal refractive surgery.

The transition from incisional methods such as radial keratotomy (RK) to excimer laser surgery, eg, photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) has dramatically increased the volume of corneal refractive surgery performed worldwide in recent years. As the current younger generation of patients who have undergone refractive surgery ages, we can assume that the presently small number of postrefractive patients requiring cataract surgery and intraocular lens implantation will increase correspondingly. This article addresses the problems encountered with calculating intraocular lens power after corneal refractive procedures. Starting with a description of keratometry in normal eyes, the causes of evident mismeasurements and miscalculation of the corneal power after keratorefractive surgery will be discussed, and different approaches to improving IOL power prediction will be described.