It is widely published that nerve fibers are present in the rim area only whereas the central cupped area of the disc is empty. In other words the optic disc is analogous to a doughnut. It also implies that someone with 0.8 cup will have all the nerve fibers in the 20% rimmed area and not in the 80% central cupped area. Although it is not mentioned, I assume the authors believe that the central empty hole is extending through the lamina cribrosa (LC) as well.

However, by reviewing the histology of the several normal and glaucomatous optic discs I have been unable to find even one single histology in which such doughnut shaped arrangement of the nerve fibers exists. Histology of the normal optic disc reveals that the entire LC is densely packed with nerve fibers and there is no central empty space.

Then, what are physiological cups? According to Wolf’s anatomy, the physiological cups are produced by the varying degree of atrophy of the Bergmeister papilla (BP); a tuft of hyaloid vessels supplying nutrition to the lens in fetal life. The remnant base of the BP is identified as central connective tissue meniscus (CCTM) lying superficially on the surface of the prelaminar nerve fibers layer quite apart from LC. If true, then why are the fibrous based on CCTM, which are not even the part of nervous tissue given so much importance in glaucoma? Why should a fibrous plate get enlarged concentrically in response to a raised IOP?

It is also mentioned that there is posterior bowing of LC in response to raised IOP. Ironically, why would raised IOP cause posterior bowing of multi-layered rigid LC and not push it outward? The nerve fibers originating closest to the disc lie most superficial (closest to vitreous) and exit from the most central part of the disc. Therefore, these central fibers should be destroyed first resulting in concentric enlargement of the blind spot and not the initial loss of peripheral fibers if cupping was indeed taking place. I am very puzzled with the term cupping which Heinrich Muller originally gave in 1856. Can someone elaborate the cupping phenomenon, as I am very confused about it? Thank you.