Estimation of the focal length of t

Estimation of the focal length of the corneal lens
The corneal lens can be regarded as a thick biconvex lens, coming in touch with air at its outer (frontal or anterior) surface and with body fluid at its inner (posterior) surface. An anterior focal length (f) and a posterior focal length (f0) are distances that were measured from different principal planes, the anterior principal plane (H) and the posterior one (H0), respectively, in a thick lens, as shown in Fig. 1. When an object (of height A) was placed at a distance s from H, and its image (height B) was formed at a distance s0 from H0 as illustrated in Fig. 1, geometric optics gave the following equations, where n0 and n2 are the refractive indices of media in the object and image side, respectively (Born & Wolf, 1964).