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R.N. Khurana, Y. Li, M.M. Lai, D. Huang; High–Speed Optical Coherence Tomography Mapping of Corneal Opacities . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1325.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the accuracy of high speed optical coherence tomography (OCT) in measuring corneal thickness in corneas with opacities.
Central corneal thickness was prospectively measured in sixteen consecutive eyes with corneal opacities using a high–speed corneal OCT prototype (Carl Zeiss Meditec Inc., Dublin, CA), Orbscan II (Bausch & Lomb Inc., Rochester, NY) and ultrasound pachymetry (Sonogage, Cleveland, OH). The OCT system has a speed of 2000 axial scans/sec and operates at 1.3 micron wavelength. Paired t–tests were used to compare measurements between pacymetry, Orbscan II, and OCT.
In patients with central opacities (n=11), there is a difference of 157.1 µm ±142 (p=0.004) between ultrasound and Orbscan II while the difference is –10.8 µm ±18 (p=0.075) between ultrasound and OCT. Figure 1 demonstrates a scatter plot of pachymetry in cases with central opacity. There is one case with a dense corneal scar where Orbscan II was unable to measure corneal topography nor corneal thickness while OCT and ultrasound were able to. In patients with off–central opacities (n=4), there is no statistically significant difference between ultrasound, Orbscan II and OCT. OCT measurements of epithelial thickness, scar depth and corneal thickness maps were also demonstrated.
High speed OCT provides reliable pachymetry mapping while Orbscan II significantly underestimates corneal thickness in the setting of corneal scars. OCT could be valuable in the planning laser and surgical treatment of corneal scars.
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