Comparative study of descemet stripping automated endothelial keratoplasty donor preparation by Moria CBm microkeratome, horizon microkeratome, and Intralase FS60

Abstract

Purpose: To evaluate the quality of stromal bed and the safety on endothelium in preparation of donor tissue for Descemet stripping automated endothelial keratoplasty in a masked fashion using 2 mechanical microkeratomes and a femtosecond laser.

Methods: Deep anterior lamellar dissection was performed on 15 donor corneas. Central endothelial cell density was calculated using specular microscopy before and after the dissection. One cornea from each of 5 donor pairs was cut with the Moria ALTK system with the CBm microkeratome using the 300-μm head and the mate cut with the Horizon disposable 300-μm microkeratome. Five additional donor corneas were cut with the Intralase 60-kHz FS laser. The donor corneas were then bisected with half of the cornea used for Live/Dead assay to study central endothelial viability. The other halves were sent for scanning electron microscopy of the stromal bed. Qualitative surface roughness of the scanning electron microscopy images was graded by 2 masked observers, and quantitative surface roughness was assessed using roughness evaluation software.

Results: The Horizon group showed a smoother stromal bed compared with the Moria or Intralase groups by 2 masked observers. However, the Moria group had the smoothest quantitative score of all the groups when assessed by roughness evaluation software. There was no statistically significant difference among the 3 groups in the percentage change in the central endothelial cell density or percentage of viable central endothelium by Live/Dead assay after the dissection.

Conclusions: Both mechanical microkeratomes created smoother stromal bed dissections than the femtosecond laser. All systems provided good endothelial cell viability.

FIGURE 1

Overlay image of maximum intensity projections of live (green) and dead (red with center mark) cells. Living cells have intracellular esterases that convert calcein AM to highly fluorescent calcein. Dead cells have damaged plasma membranes that allow ethidium homodimer-1 to enter and become fluorescent when bound to nucleic acids.

FIGURE 2

Representative SEM images (×14) of stromal bed of donor cornea cut with Horizon (A) compared with Moria microkeratome (B). Fine stromal ridges were occasionally seen with the Moria (arrow).

FIGURE 3

Representative SEM images (×200) of stromal bed cut with Horizon (A), Moria (B), and Intralase (C) used for quantitative assessment of smoothness with SPIP software.

FIGURE 4

A, The femtosecond dissection resulted in a variable quality deep stromal bed with a smooth bed using raster energy = 0.6 μJ and a new applanation cone. B, Raster energy = 0.5 μJ and a used applanation cone resulted in a rough surface with a central depression (arrow) and peripheral pits (arrow-head) (×14). C, The femtosecond dissection occasionally resulted in significant pitting of the stromal bed (×200).