Corneal topographic analysis in patients with keratoconus using 3-dimensional anterior segment optical coherence tomography

PURPOSE: To assess a new corneal topographer based on 3-dimensional anterior segment optical coherence tomography (OCT-based corneal topographer) for analyzing corneal topography in patients with keratoconus. SETTING: Osaka University Graduate School of Medicine, Osaka, Japan. DESIGN: Evaluation of diagnostic test or technology. METHODS: Keratoconic eyes and normal control eyes were assessed using a rotating Scheimpflug-based corneal topographer and an AS OCT-based corneal topographer. The OCT-based corneal topographer, a 1310 nm swept-source device, captures 8192 points during 0.34 second for 16 radial scans of the corneal topography. The success rate of precisely digitizing the corneal surfaces, patterns of the color-coded maps, central corneal thickness (CCT), and central axial power were compared between the 2 devices. RESULTS: Forty keratoconic eyes and 30 control eyes were assessed. The OCT-based corneal topographer measured corneal configurations despite corneal opacities. The success rate of precisely digitizing the corneal surfaces in keratoconic eyes was 95% using OCT and 80% using the Scheimpflug-based corneal topographer. The color-coded maps of the anterior and posterior corneal elevations, CCT, and corneal axial power maps generated by the 2 devices agreed well. The correlations between the CCT values and between the central corneal axial power values measured by the 2 devices were well correlated in both groups. CONCLUSIONS: The OCT-based corneal topographer, with its faster acquisition time, provided more consistent measurements than the Scheimpflug-based corneal topographer. The OCT-based corneal topographer seems promising for evaluating highly irregular corneas, as in cases of advanced keratoconus.