Comparison of Refraction-Derived Keratometric Value and Orbscan Corneal Power after Laser in Situ Keratomileusis

ABSTRACT

PURPOSE: To determine the Orbscan corneal power which gave the best correlation with refraction-derived keratometric value (clinical history method) after LASIK in cataract surgery. METHODS: A total of 38 consecutive eyes of 19 patients who were followed up for at least 1 year after LASIK were included in study. The refraction-derived keratometric values were correlated with Orbscan corneal power within 1, 2, 3, 4, and 5 mm diameter zones of keratometric, anterior and total selections of mean, axial, tangential and optical power maps. RESULTS: The Orbscan corneal power of the 5-mm zone optical power total map gave the best correlation with refraction-derived keratometric value. The following regular relationship in linear regression analysis was derived: RDKV(refraction-derived keratometric value)=0.9 X OPT5(corneal power of Orbscan optical power total map 5-mm zone)+4.941(r=0.883). CONCLUSIONS: These results indicate that the corneal power of the 5-mm zone optical power total map was the most appropriate to calculate IOL power in cataract surgery after LASIK when using Orbscan topography.