[Abnormal distribution of trace elements in keratoconic corneas]

Our understanding of etiology and pathogenesis of many disorders, corneal included, greatly relies on existing knowledge in human biochemistry and biophysics. This study was aimed at chemical mapping of normal and keratoconic corneas.

Modern methods of analytical chemistry, such as X-ray fluorescence and energy-dispersive X-ray spectroscopy on the basis of scanning electron microscopy, were adapted to the needs of cornea research. Normal human corneas obtained postmortem and corneal buttons obtained during penetrating keratoplasty were analyzed.

In keratoconus, abnormal accumulation of iron, copper, and zinc was found in the periphery of the buttons, i.e. in the zone of visible pigmentation (Fleischer ring), while the center - the ectatic zone - demonstrated a total deficiency of trace elements. This data suggests that keratoconus pathogenesis is associated with impaired mineral metabolism and formation of a physicochemical barrier in corneal tissues with subsequent keratectasia. The authors discuss several possible vicious circles involved.