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Ana I. Ortiz, Manuel Ramirez, Francisco Beltran, Andrea Portilla, Alberto Hernandez, Everardo Hernandez-Quintela; LASIK: Validity of Online Corneal Pachymetry. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4034.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the grade of agreement and correlation between Optical Coherence Tomography Online Pachymetry (OCT-OP) and Ultrasound Pachymetry (US-P) measurements of central corneal thickness during LASIK.
50 eyes of 25 patients underwent standard LASIK (M2 Moria, microkeratome, Doylestown, USA; Schwind Amaris Excimer Laser, Kleinostheim, Germany). 15 females and 10 males were enrolled in the study with a mean age of 35 ± 9.2 years. Mean preoperative sphere was -4.37 ± 2.18. Mean preoperative cilynder was -2.87 ± 1.15. Measurements were taken with both methods (OCT-OP and US-P) at 3 different time points during the procedure: before the corneal flap creation, measurement of the stromal bed after flap lifting and, after flap replacement. A correlation and agreement analysis was performed through a regression analysis, intraclass correlation coefficient estimate and a Bland and Altaman strategy.
The Mean preoperative central corneal thickness was 434.1 ± 97.5 microns and 433.8 ± 97.5 by OCT and US, respectively. A linear regression analysis showed an r=0.99 (p < 0.001, y=.99x+2.8). The interclass correlation coefficient was 0.99 (CI 95%, 0.98 - 0.99). Mean difference of measurements was 0.26 ± 9.81 microns, 94% of cases had a difference between instruments from -19.36 to 19.88 microns
Data found suggests that there is a high level of correlation and agreement between OCT-P and US-P during LASIK. OCT-P online appears to be a reliable method to evaluate corneal thickness. A lower degree of agreement was observed in higher corneal thickness values.
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