Keratectasia After LASIK

December’s Archives

Meghpara et al. examined the histopathologic and immunohistochemical features of corneal buttons from patients who developed keratectasia after LASIK.
Five keratectasia corneal buttons were obtained during penetrating keratoplasty. Histologic features were examined by hematoxylin-eosin staining using paraffin-embedded sections and by transmission electron microscopy. Immunostaining for alpha1-proteinase inhibitor, Sp1, and matrix metalloproteinases 1, 2 and 3 was performed with two normal human corneas and two corneas with keratoconus as controls.
Central stromal thinning was observed after hematoxylin-eosin staining in all corneas with keratectasia. By transmission electron microscopy, collagen fibril thinning and decreased interfibril distance were observed in the stromal bed. However, no histologic features specific to keratoconus—including Bowman’s layer disruption—were identified in the corneas with keratectasia. Immunostaining intensity and/or pattern for alpha1-proteinase inhibitor and Sp1 in the corneas with keratectasia was comparable to that of normal control corneas but different from that of keratoconus. No significant staining with anti-matrix metalloproteinases 1, 2 and 3 antibodies was observed in either the corneas with keratectasia or the normal controls.
The authors conclude that post- LASIK keratectasia results in collagen fibril thinning and decreased interfibril distance within the residual stromal bed. Discrepant immunohistochemical findings between keratectasia and keratoconus suggest that the pathogenesis of the two conditions differ