Figure 4. Histopathological features of affected cornea from the right eye of the proband carrying the homozygous TGFBI R124H mutation at the age of 43. The visual acuity of the proband before penetrating keratoplasty was 20 cm/CF. A: Light microscopy of excised corneal tissue stained with congo red revealed variably sized and irregularly shaped deposits of amyloid material, predominantly in the anterior and middle stroma (arrows). B: The deposits stained with Masson’s trichrome showed brightly red accumulation of hyaline under the Bowman's membrane (arrows). The epithelium showed focal areas of dehiscence from Bowman's membrane.