Secondary anterior crocodile shagreen of Vogt.

The clincopathological features and pathogenesis of secondary mosaic degeneration of the cornea (anterior crocodile shagreen of Vogt) are described. The structural basis for the normal anterior corneal mosaic pattern seems to lie in the particular arrangement of many prominent collagen lamellae of the anterior stroma that thake an oblique course to gain insertion into Bowman's layer. Since, at normal intraocular pressure, Bowman's layer is under tension, when viewed from the anterior surface the cornea appears smooth. By releasing the tension, however, a reproducible polygonal ridge pattern becomes manifest. It is suggested that a prolonged phthisical state of the eye is one condition wherein the mosaic pattern may become permanent and that, as a secondary event, this is followed by irregular calcification of Bowman's layer which particularly involves the ridges projecting into the epithelium. Biomicroscopically these ridges corresponded to the branching reticular arrangement of the mosaic opacities.