Posters

Repeatability of corneal and epithelial thickness measurements with Fourier domain optical coherence tomography

Poster Details

First Author: E.Miller UK

Co Author(s):    D. Reinstein   T. Archer   M. Gobbe        

Abstract Details

Purpose:

To assess the repeatability of epithelial and corneal thickness measurements using optical coherence tomography (OCT).

Setting:

London Vision Clinic, London, UK

Methods:

Five consecutive measurements were obtained for 10 eyes of 10 pre-operative patients and 10 eyes of 10 patients at least 3 months after LASIK using the RTVue Fourier-domain OCT. An equal amount of right and left eyes, chosen at random, were included for each group. Data were obtained according to the zonal averages included in the standard RTVue mapping of epithelial thickness within the central 6-mm diameter zone. Zonal averages were calculated for the central 2-mm diameter zone, 8 zones equally distributed within an annulus between the 2 and 5-mm diameter rings, and 8 zones equally distributed within an annulus between the 5 and 6-mm diameter rings. Repeatability analysis was performed for each zone and the thinnest point including the standard deviation, coefficient of repeatability (COR, 1.96xSD) and coefficient of variation (COV, COR/mean).

Results:

For corneal thickness in the pre-op group, the repeatability was 1.75μm (COR 3.43μm, COV 0.66%) centrally and 1.44μm (COR 2.82μm, COV 0.55%) for the thinnest point. The worst repeatability was found in the superonasal zone of the outer annulus. Repeatability was 8.45μm (COR 16.56μm, COV 2.77%). For corneal thickness in the post-LASIK group, the repeatability was 1.24μm (COR 2.44μm, COV 0.50%) centrally and 1.14μm (COR 2.23μm, COV 0.46%) for the thinnest point. The worst repeatability was found in the superior zone of the outer annulus. Repeatability was 10.70μm (COR 20.97μm, COV 3.63%). For epithelial thickness in the pre-op group, the repeatability was 0.81μm (COR 1.59μm, COV 3.05%) centrally and 0.73μm (COR 1.43μm, COV 2.87%) for the thinnest point. The worst repeatability was found in the superior zone of the outer annulus. Repeatability was 1.18μm (COR 2.32μm, COV 4.46%). For epithelial thickness in the post-LASIK group, the repeatability was 0.69μm (COR 1.36μm, COV 2.44%) centrally and 1.00μm (COR 1.97μm, COV 3.78%) for the thinnest point. The worst repeatability was found in the temporal zone of the outer annulus. Repeatability was 1.37μm (COR 2.69μm, COV 5.01%).

Conclusions:

Measurement of corneal and epithelial thickness showed high repeatability with the RTVue for pre-operative and post-LASIK eyes. FINANCIAL INTEREST: One of more of the authors... has significant investment interest in a competing company