Abstract
Purpose:
Descemet’s stripping automated endothelial keratoplasty (DSAEK) has replaced penetrating keratoplasty as the treatment of choice for corneal endothelial dysfunction. Surface quality of the donor button plays an important role in determining the visual outcome following DSAEK. This study measured and compared the surface roughness of endothelial grafts dissected with a femtosecond laser (FS) and two mechanical microkeratomes (MKs).
Methods:
Endothelial buttons were harvested from 18 human corneas unsuitable for transplantation with the Intralase FS60 laser (Abbott Medical Optics, Santa Anna, Ca.; n=4) and the Moria ALTK (Moria, Antony, France; n=6) or the Gebauer SLc MKs (Gebauer Medizintechnik, Neuhausen, Germany; n=8). Following dissection the endothelial buttons were fixed in 3.0% glutaraldehyde and examined using a confocal profiler (Sensofar PLu 2300, Terrassa, Spain) and environmental scanning electron microscopy (ESEM) (FEI-Quanta 600; Hillsboro, OR). Linear mixed model analysis was used to quantify the difference in surface roughness between the different dissection techniques.
Results:
Confocal profiling was able to obtain quantitative surface roughness measurements and high resolution 3-dimensional reconstructions of the central 2x1.5 mm2 area of the dissected buttons. ESEM evaluation allowed wide field analysis at lower magnification which corresponded well with the 3-dimensional confocal reconstructions. Surface roughness of FS dissected buttons (RMS =1.89 µm) was significantly higher compared with the Moria (RMS=1.05 µm) and Gebauer MKs (RMS=0.92 µm) (p<0.01). However, there was no significant difference between the surface roughness of the MK dissected buttons (p=0.29) despite ultrastructural differences between the buttons as demonstrated by the 3-dimensional reconstruction and ESEM analysis.
Conclusions:
FS laser dissection of corneal buttons results in significantly rougher stromal surfaces compared to mechanical MKs. MK dissected corneal buttons did not differ in surface roughness. Confocal profiling, a novel non-contact optical profiling method, enables submicron surface roughness measurements and 3-dimensional reconstructions of large areas of human corneal buttons, corresponding well with qualitative 2-dimensional ESEM imaging. This innovative technology may be useful for quality judgement of lamellar dissection techniques.
Keywords: 479 cornea: clinical science •
480 cornea: basic science •
551 imaging/image analysis: non-clinical