Comparative evaluation of tomographic and biometric characteristics in bilateral keratoconus patients with unilateral corneal Vogt's striae: a contralateral eye study

Purpose: The aim of this study was to evaluate and compare tomographic and biometric characteristics measured by the corneal tomography and ocular biometry in bilateral keratoconus (KCN) patients with and without corneal Vogt's striae. Methods: Ninety-two eyes of 46 subjects with a reliable diagnosis of bilateral KCN with unilateral Vogt's striae were enrolled in this cross-sectional contralateral eye study. In addition to refraction (calculated by vectorial analysis) and visual acuity, corneal tomographic measurements were obtained by the Pentacam (Scheimpflug-based anterior segment tomography). Also, ocular biometric characteristics were evaluated using the Ocuscan (R) RxP (ultrasound biometer). The KCN eyes were categorized into two groups, including eyes with Vogt's striae and eyes without Vogt's striae. Results: Our results showed significant differences in the sphere, cylinder, spherical equivalent, J0, corrected and uncorrected distance visual acuity, flat, steep and maximum keratometry, anterior chamber depth (ACD), and central corneal thickness (CCT) between the two groups (all P<0.001). The eyes without Vogt's striae had a shorter ACD measured by the Pentacam and biometer. There were no differences in axial length (AL) and vitreous length (VL) between the two groups (all P>0.05). Also, there was poor agreement between the measurements of the Pentacam and ultrasound biometer for ACD in the study groups. Conclusion: Corneal tomographic and ocular biometric measurements showed significant differences between KCN eyes with and without Vogt's striae except for AL and VL. These differences should be noticed in clinical evaluations and treatment of KCN patients.