Ocular ochronosis. Clinicopathological, histochemical, and ultrastructural studies
A. Kampik, J. N. Sani and W. R. Green
Presented here are the clinical, histological, histochemical, and
ultrastructural findings of an eye with notable ochronotic changes.
Ochronotic pigment is seen by light microscopy as amber globules or
fiber-like structures in the cornea, conjunctiva, and sclera combined with
degenerated collagen. In the area of a previous injury the intense
involvement of the cornea, which is usually not notably involved, indicates
the role of preexisting degeneration for the development of clinically
visible pigmentation. Although the ultrastructure of the ochronotic pigment
is similar to melanin, the chemical behavior is different and, it seems,
similar to elastin. Ultrastructurally, most of the pigment granules are
extracellular, partly altering the collagen fibers and fibrocytes. The
electron-microscopically observed four patterns of deposition are
interpreted as stages in the development of ochronotic deposits, according
to biochemical findings in the literature.
