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Clinical validation of an adjusted corneal power estimation algorithm in patients with previous LASIK surgery

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Session Details

Session Title: Presented Poster Session: Laser Refractive Surgery

Session Date/Time: Sunday 06/09/2015 | 15:00-16:30

Paper Time: 16:10

Venue: Poster Village: Pod 2

First Author: : D.Piñero SPAIN

Co Author(s): :    V. Camps   A. Artola   V. Mateo   R. Perez-Cambrodi   P. Ruiz-Fortes  

Abstract Details


To validate clinically an algorithm for the minimization of the errors in the estimation of corneal power when using a keratometric index (nk) in eyes with previous LASIK surgery for the correction of myopia


Department of Ophthalmology (OFTALMAR), Vithas Medimar International Hospital, Alicante, Spain


A total of 62 myopic eyes (range, -1.00 to -6.00 D) of 62 ranging in age from 21 to 52 years were enrolled in the study. All patients underwent LASIK surgery using the Pulzar Z1 solid-state laser (CustomVis Laser). Corneal power was measured with the Pentacam system (Oculus) considering both corneal surfaces and neglecting (Gaussian corneal power, PcGauss) or not the corneal thickness (True Net Power, TNP). Likewise, the keratometric corneal power considering a variable keratometric index was calculated (Pkadj): nkadj=-0.0064286 r1c +1.37688. Agreement between of Pkadj with PcGauss, TNP and Haigis-L approach (PHaigisL) was evaluated


Statistically significant differences (p<0.01) were found between Pkadj and PcGauss, but not (p=0.319) between Pkadj and TNP. Mean difference between Pkadj and PcGauss was 0.14  0.24 D, with limits of agreement of -0.33 and +0.60 D. Mean difference between Pkadj and TNP was 0.03  0.24 D, with limits of agreement of -0.50 and +0.44 D. A strong and statistically significant correlation was found between Pkadj and PcGauss (r=0.994, p<0.01) and between Pkadj and TNP (r=0.994, p<0.01). Mean difference between Pkadj and PHaigisL was -0.04  0.17 D, with limits of agreement of -0.37 and +0.29 D


The keratometric approach using the proposed adjusted keratometric index (nkadj) is a valid and easy method to estimate the corneal power after myopic LASIK and comparable to that proposed by the Haigis-L approach

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