Figure 2 of Steinhart, Mol Vis 2012; 18:1093-1106.

Figure 2. Schematic for scleral analysis. Schematics for the scleral analysis indicate the meridional and circumferential directions with angles Φ and θ, respectively, and the radius of curvature of the undeformed meridian with R2. A: The superior view of the sclera with curvilinear coordinates (Φ), which is used to locate a point along the scleral edge. B: The posterior view of the sclera indicating the two principal directions used for strains and stress calculations. C: The superior view of the undeformed (solid line) and deformed (dashed line) scleral edge, indicating the undeformed position, X(s), the deformed position, x(s), the displacement vector, u(s), and the diameters d and D of the deformed and undeformed cross-sections at s, respectively.