Fig. 4.

Schematic representation of contact stress and deformation according to contact mechanics. a, The image illustrates two interacting spheres where the point of maximum contact pressure is located centrally, resulting in a semi elliptic pressure distribution, as depicted by the green dashed elliptic area in C. b and c, These images demonstrate that the theory is applicable even when a spheroid object, such as a retinal cyst, engages with a more or less flat surface, akin to the retina. This principle holds because even a “flat” plate can be equated to a sphere with an infinite radius, as shown in B

Legends: F, forces between the bodies; R, radii of curvature; a, radius of the contact area; d, depth of deformation; E, moduli of elasticity; ν, Poisson’s ratios; d, depth of identation; R*, flat surface with an infinite radius; E*, undeformable solid