Comparison of Four Systems of IOL Calculation after Keratorefractive Surgery in Eyes Requiring Cataract Surgery

ABSTRACT

PURPOSE: To report the evaluation and comparison of true corneal power after corneal refractive surgery through ARK, Orbscan II(R), Pentacam and IOL master. METHODS: Target IOL (Intraocular lens) power calculated with the SRK/T formula using SMK (Sungmo Eye Hospital keratometry), which is a new method for measuring corneal refractive power, was compared with the back-calculated ideal IOL power after cataract surgery for 30 eyes that required cataract surgery and had previously undergone refractive surgery. Target IOL powers calculated using 4 systems were compared with IOL power calculated using the clinical history method for 64 eyes that had undergone refractive surgery. RESULTS: Using SMK with the SRK/T formula, the actual refraction was within +/-0.5 diopter (D) of the intended refraction for 63.8% of eyes and within +/-1.0 D for 90.9% of eyes. Compared with target IOL power calculated with the clinical history method, target IOL power calculated by SMK with the SRK/T formula had a difference of 1.95 +/- 0.86 D, which was similar to the results calculated by the Haigis-L formula and by TNP with Haigis. CONCLUSIONS: The method of IOL calculation using SMK with the SRK/T formula showed the best predictability in patients after corneal refractive surgery. Comparatively accurate results were produced in IOL power calculations using the Haigis-L formula, and the TNP with Haigis method.