A structural investigation of corneal graft failure in suspected recurrent keratoconus

Penetrating keratoplasty was performed on the right eye of a 51-year-old patient diagnosed with advanced bilateral keratoconus. Thirteen years later, an 8.5 mm regraft was required as a result of gross vascularisation, a poor epithelium, and suspected recurrent keratoconus. To learn more about the structural basis for graft failure, we examined the removed tissue for the presence of abnormalities in the stroma and limiting membranes.

X-ray scattering and electron microscopy were used to study the failed-graft tissue to provide information on the integrity of the limiting membranes and the diameter, dominant orientation, and distribution of collagen within the corneal stroma. The findings were compared with similar structural data from normal and keratoconus corneas.

In contrast to the keratoconus cornea, a normal orientation and distribution of collagen was seen throughout most of the failed-graft tissue, although abnormalities were observed in the infero-nasal quadrant at the original graft/host junction. The average diameter of collagen fibrils in the failed-graft button did not differ from that of normal corneas.

The structural abnormalities identified in this case of graft failure were not consistent with those typically seen in keratoconus. The clear demarcation of the graft/host boundary 13 years after surgery suggests that a normal stromal collagen arrangement may never be fully achieved in corneal graft wounds.