Abstract
Purpose::
To determine the safety and efficacy of the Intralase® and the Moria ALTK® in creating pre-cut endothelial keratoplasty donor tissue
Methods::
Sixteen corneoscleral buttons from 8 donors were evaluated within 2 days of the death of donor. The mean donor age was 72 years and mean death to preservation time was 11 hours. Eight eyes underwent deep lamellar keratectomy using the femtosecond laser (FL) (Intralase® - firing rate 30 kHz , lamellar cut energy 7.4 uJ, side cut energy 5.5 uJ, spot size 10 uM, diameter 9.0, depth 400 microns, spiral pattern), while the other 8 eyes were cut using the Moria ALTK® microkeratome (M) (350 micron head). Ultrasonic pachymetry and endothelial cell density (ECD) were done before, immediately after, and 48 hours after keratectomy. The residual stromal bed was examined with electron microscopy to determine the smoothness of the surface. Cell viability was assessed using a TUNEL assay.
Results::
There was no statistically significant difference in the mean preoperative pachymetry between the two groups, being 576+/-34 microns in the FL group and 557+/-28 microns in the M group. There was a statistically significant difference in anterior flap thickness, with the M group displaying a consistently deeper keratectomy (447+/-27 vs. 399+/-41 microns) (p=0.023), and thinner residual stromal bed (115+/28.5 vs. 177+/-42 microns)(p=0.005). The mean ECD was similar in each group, being 2427+/-434 cells/mm2 in the FL group and 2308+/-402 cells/mm2 in the M group. Forty-eight hours after keratectomy, there was no statistically significant difference in ECD between the two groups, comparing to the preoperative state, there was a 4% and 1% reduction in ECD in FL and M groups respectively (p=0.436). Electron microscopy of the stromal surface consistently showed a smoother contour in the M group. Neither group demonstrated significant endothelial cell toxicity via TUNEL assay.
Conclusions::
The femtosecond laser is as effective as microkeratome in creating pre-cut endothelial keratoplasty (EK) donor tissue, without displaying adverse side effects. The less smooth stromal surface created by the femtosecond laser may improve disc adherence, which continues to be a problem in EK. A prospective, randomized clinical study which evaluates the efficacy and safety of femtosecond laser produced EK donor tissue is planned for the future.
Keywords: cornea: endothelium • transplantation • cell survival