High-speed Optical Coherence Tomography of Corneal Opacities

Abstract

To evaluate corneal opacities with optical coherence tomography (OCT). Prospective observational case series. Twenty-three eyes of 19 patients with corneal opacities referred to a tertiary medical center. Twenty-three consecutive eyes with corneal opacities were imaged with a high-speed corneal OCT prototype (Carl Zeiss Meditec, Inc., Dublin, CA). The OCT system operates at a speed of 2000 axial scans per second and a wavelength of 1.3 microm. Slit-scanning tomography (Orbscan II, software version 3.12; Bausch & Lomb, Inc., Rochester, NY) and ultrasound pachymetry (Corneo-Gage Plus; Sonogage, Cleveland, OH) also were performed. Central cornea thickness was measured by the 3 instruments. In eyes with central opacities (n = 17), OCT central cornea thickness measurements were statistically equivalent to ultrasound pachymetry, whereas Orbscan II measurements were significantly less than ultrasound pachymetry (difference, -132.7+/-143 microm; P = 0.006). The OCT and ultrasound pachymetry results were obtained for all eyes, whereas Orbscan was unable to provide readings in 4 eyes. In eyes with off-center opacities (n = 6), OCT and Orbscan II central cornea thickness measurements were statistically equivalent to ultrasound pachymetry. The OCT measurements of epithelial thickness and scar depth also were demonstrated. Optical coherence tomography provides consistent pachymetry mapping, whereas Orbscan II significantly underestimates corneal thickness in the presence of central corneal scars. Optical coherence tomography could be valuable in the planning of surgical treatment of corneal scars.