Comparison of IOL powers by corrected method in eyes after PRK and LASIK

Koo, O Sub; Kim, June Gone; Song, Byung Joo

Abstract

The purpose of this study is to compare, by statistical analysis, intraocular lens (IOL) powers by SRK/T formula using autorefractokeratometer-measured keratometric (K) values (SRK/T-ARK-mK), by SRK/T formula using refraction-derived K values (SRK/T-R-dK), and by refraction corrected method (RCM), in eyes treated with photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) for myopia. Thirty-eight consecutive eyes of 23 patients with PRK for mild to moderate myopia and 35 consecutive eyes of 25 patients with LASIK for high myopia were followed up for more than 1 year. In the two groups, IOL powers by SRK/T-ARK-mK, by SRK/T-R-dK, and by RCM were compared by statistical analysis. In PRK group, the mean value of IOL powers by RCM was statistically higher than that obtained by the other two methods (p < 0.05), while there was no significant statistical difference between the mean values of IOL powers by SRK/T-ARK-mK and by SRK/T-R-dK (p > 0.05). However, in LASIK group, the mean values of IOL powers by RCM and by SRK/T-R-dK, which did not differ statistically (p > 0.05), were both statistically higher than that by SRK/T-ARK-mK (p < 0.05). In conclusion, there is a statistical difference in IOL powers by the methods used for IOL calculation, as there is according to the level of myopia in patients with PRK and LASIK treatment. We suggest that, in IOL power calculation in eyes with previous corneal refractive surgery, correction methods such as RCM and SRK/T-R-dK are more effective at higher levels of myopia.