Abstract
Purpose: :
To analyze histopathological changes of corneal tissue caused by deep anterior lamellar keratoplasty (DALK) using the "big bubble" technique in patients with keratoconus, their variability in 10 patients and their possible clinical implication.
Methods: :
The excised anterior corneal lamellae of 10 keratokonus patients having undergone deep anterior lamellar keratoplasty (DALK) using the big-bubble technique were analyzed by light and transmission electron microscopy. In addition, clinico-pathological correlations and immunohistochemistry were done. Intralstromal air accumulations were quantified morphometrically.
Results: :
Intrastromal air was detected in all examined excised lamellae (overall 8 % of stromal volume), but with a large variability (SD 8.8). Intrastromal air bubbles were characterized by round shape, mean size of 1379 µm² (SD 1031) and surrounding collagen displacement causing a "pseudo capsule". The air was predominantly located at one periphery of the excised lamella and represented there up to 38 % of stromal volume. The different distribution of intrastromal air in the periphery was statistically significant (p=0.016).To differentiate intrastromal air from histopathological differential diagnoses we performed a CD68 staining which was negative. We detected no air-injection induced alterations of Bowman’s layer and epithelium by light and electron microscopy.
Conclusions: :
Our results show that "big-bubble DALK" causes significant intrastromal air accumulations in the cornea. Pathologists should be conscious of this phenomenon and the high topographic variability. Intrastromal air in the recipient rim may be accompanied by a decrease of mechanical stability and may contribute to postoperative suture loosening. In consequence, the surgeon should try to limit the injection of air to the excised central stroma.
Keywords: cornea: clinical science