Fig. 7

Ocular surface alignment (angle kappa) and scleral curvature changes along with axial length. a The composite anterior segment tomographic image of an eye with shorter axial length (21.93 mm) and larger angle kappa (6.39°); the extracted ocular surface outline from this image is the red line in d. b The composite image of an eye with medium axial length (25.40 mm) and medium angle kappa (4.72°); the extracted ocular surface outline is the green line in d. c The composite image of an eye with longer axial length (27.38 mm) and smaller angle kappa (1.68°); the extracted ocular surface outline is the blue line in d. d The overlap of the lines extracted from the outermost layer of the ocular surface using the MATLAB software. The red line represents the eyes with shorter axial length (Fig. 7a), the green line represents medium axial length (Fig. 7b), and the blue line represents longer axial length (Fig. 7c). The nasal scleral curvature flattens considerably less than the temporal side owing to the flattening of the scleral curvature with longer axial length, counteracted by the steepening effect of the accompanying decreased angle kappa