Articoli Scientifici di Oftalmologia

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Repeatability of corneal epithelial thickness measurements using Fourier-Domain Optical Coherence Tomography in normal and Post-LASIK eyes

To evaluate the repeatability of corneal epithelial thickness (ET) and corneal thickness (CT) measurements in normal and LASIK eyes using the optical coherence tomography (OCT, RTVue).

Methods—In 35 right eyes of 35 normal subjects and 45 right eyes of 45 subjects with prior myopic LASIK, corneal ET and CT were evaluated in 17 areas: 1) one central zone within 0-2.0 mm diameter, 2) eight paracentral zones from 2.0-5.0 mm diameter, and 3) eight peripheral zones from 5.0-6.0 mm diameter. The repeatability was assessed using within-subject standard deviation (SD), coefficient of variation (CoV), and intraclass correlation coefficient (ICC).

 Results—At the central and paracentral zones, respectively, the SD values were 0.7 μm and 0.6-0.9 μm in normal eyes and 0.7 μm and 0.8-1.7 μm in LASIK eyes for ET, and 1.0 μm and 2.8-4.6 μm in normal eyes and 1.3 μm and 4.0-4.8 μm in LASIK eyes for CT. At the peripheral zones, in normal and LASIK eyes, respectively, SD values ranged from 0.8-1.2 μm and 1.4-2.2 μm for ET, and 4.1-6.4 μm and 6.0-9.1 μm for CT. The CoV values were low and ICC values were high in both groups for both ET and CT measurements.

Conclusion—The OCT produced excellent repeatability, especially at the central and paracentral zones up to 5-mm diameter for both corneal epithelial thickness and corneal thickness measurements.