Correcting the corneal power meaurement for intraocular len power calculation after myopic laer in itu keratomileui

Purpoe To decribe and evaluate a refraction-derived method and a clinically derived method to calculate the correct corneal power for intraocular len (IOL) power calculation after laer in itu keratomileui (LAIK) and to compare the reult to the commonly ued hitory-derived method. Deign Interventional cae erie. Method Retropective analyi of conecutive cae from clinical practice. Two hundred randomly elected eye from 200 patient were evaluated before and after LAIK urgery. For each patient, we etablihed the pre-LAIK and pot-LAIK pectacle refraction, the pre-LAIK (Kpre) and pot-LAIK K reading (Kpot). We then calculated for each cae the pre- and pot-LAIK refraction at the corneal plane and the amount of correction obtained by the refractive urgery (CRc). The cae were divided into two group. Group I wa ued to derive the two formula. The K value were calculated uing the hitory-derived method (Kc.hd) in which Kc.hd = Kpre – CRc. Kc.hd wa compared with Kpot. The average difference wa 0.23 diopter for every diopter of myopia corrected. Thi value wa ued to calculate the corneal power uing the refraction-derived method (Kc.rd) where Kc.rd = Kpot –0.23CRc. A regreion equation wa ued to develop a clinically derived method (Kc.cd) where Kc.cd = 1.14Kpot –6.8. The value obtained with the two method were compared with the Kc.hd value in group II to validate the reult. Reult Both Kc.rd and Kc.cd value correlated highly with Kc.hd when plotted on a cattergram (P < .001), and there wa no tatitically ignificant difference between the mean keratometric value (P > .5). Concluion The corneal power meaurement for intraocular len power calculation after LAIK need to be corrected to avoid hypermetropia after cataract urgery by either the hitory-derived method, the refraction-derived method, or the clinically derived method.