Measurements of corneal/scleral sagittal height and corneoscleral junction shape using ultra-long scan depth spectral domain optical coherence tomography

Objective To investigate corneoscleral dimensions and sagittal heights in the cornea and sclera using ultra-long scan depth spectral domain optical coherence tomography (UL-OCT).Methods This was a cross-sectional investigation.Forty subjects (80 eyes,17 men,23 women; mean age,25.8±2.8 years) were recruited for the study.UL-OCT image acquisition was taken for each eye.Custom software was used to quantify corneal/scleral sagittal height and dimensions of the corneoscleral junction.The differences in sagittal heights and dimensions of the corneoscleral junction in the four quadrants were analyzed with a paired t test and repeated measures ANOVA.Results There were no significant differences in the X and Y axis coordinates in the corneoscleral junction,the tangential curvature difference between the corneoscleral junction and the mean tangential curvature of the central 3 mm cornea and the corneal/scleral sagittal height (chord distances of 1.5,3,5 and 7 mm from the corneal apex) in the same locations between the left and right eyes.Except for the X axis coordinates,other dimensions were larger on the nasal side than the temporal side (P＜0.05).There were no significant differences among all dimensions between the superior and inferior sides at the vertical meridian.The values of the X axis coordinates at the vertical meridian were closer to the corneal apex than the horizontal meridian.The values of the Y axis coordinates and the tangential curvature difference between the corneoscleral junction and the mean tangential curvature of the central 3 mm cornea were largest on the nasal side compared to other locations (P＜0.05).Conclusion There are no significant differences for any dimensions at the same location between the left and right eyes.The comeosclera presents a larger junction angle on the nasal side than at other locations. Key words: Ocular surface;  Sagittal height;  Corneoscleral junction;  Tomography,optical coherence