Histopathology and spectral domain OCT findings of pneumatic-assisted dissection in DALK.

Purpose: To correlate big-bubble deep anterior lamellar keratoplasty findings in donor corneas with anterior segment optical coherence tomography (OCT) and histology.
Methods: This research was conducted entirely at the University of Texas Southwestern Medical Center in Dallas, Texas. We performed deep intrastromal air injections in donor corneas on artificial chambers. Surgical patterns (big bubble, intrastromal emphysema, and perforation) were assessed by spectral domain OCT with a handheld probe and histology.
Results: Surgical patterns were evaluated by histology using a novel embedding technique. A classic big bubble may be a Descemet membrane (DM) detachment with a few attached stromal fibrils. There were no large intra-DM separations as previously reported. The emphysematous surgical patterns result from intrastromal emphysema, which can be accompanied by microdetachments of DM. We saw indirect OCT signs of big bubble, but scatter from intrastromal emphysema limits deeper imaging.
Conclusions: Surgical patterns of big bubble and intrastromal emphysema correlate with characteristic histology findings. Marked scatter on OCT by intrastromal emphysema limits visualization of deeper corneal structures, but the presence of a big bubble may be inferred.