Calculating intraocular lens power in eyes with keratoconus using videokeratography

A patient with keratoconus had cataract extraction and intraocular lens (IOL) implantation in both eyes. The IOL power was determined using keratometric values (K-values) measured by standard keratometry in the right eye and videokeratography in the left eye. The ideal IOL power and the K-value that would have led to the ideal IOL power were determined from the postoperative refraction at 6 weeks. The ideal K-value was compared with the K-values derived from videokeratography and standard keratometry. Refraction at 6 weeks postoperatively was 5.60 and 1.00 diopter more myopic than the aim in the right and left eye, respectively. The mean power in ring 3 in videokeratography of the left eye was the same as the ideal K-value calculated using the Holladay formula. Determining IOL powers with videokeratography-derived K-values might be more accurate than standard keratometry in patients with keratoconus.