Intraocular lens power calculation after refractive surgery

Abstract

Purpose: To analyze the results of phacoemulsification cataract surgery in eyes that had had refractive surgery and to compare the predictability of various methods of intraocular lens (IOL) power calculation. Setting: Instituto de la Visión, Buenos Aires, Argentina. Methods: The study involved 7 cases that had phacoemulsification after radial keratotomy or laser in situ keratomileusis. The spherical equivalent (SE) and visual acuity were evaluated preoperatively and postoperatively to assess the changes before cataract development. The IOL power calculated with conventional keratometry (CK), adjusted keratometry, the clinical history method (CHM), corneal topography (CT), and the contact lens method (CLM) was compared with the final refractive and keratometric results measured with the BackCalcs (Holladay® IOL Consultant Program, Holladay Consulting, Inc.) to assess the accuracy and predictability of each method. Results: The mean SE was –4.82 diopters (D) ± 5.13 (SD) before phacoemulsification and +0.19 ± 1.01 D after phacoemulsification, and the mean best corrected visual acuity was 0.39 ± 0.07 (20/50) and 0.80 ± 0.06 (20/25), respectively. Conclusions: Post-phacoemulsification refraction in cases with previous refractive surgery appeared to be predictable when the appropriate calculation method was applied. When all the data were available, the CHM provided the best results. Adjusted keratometry and CT seemed to be more accurate than CK and the CLM.