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DSAEK GRAFTS WITH PARALLEL FACES : IS THE FUTURE? Luca Avoni IV ivis suite user meeting Innsbruck, 6 July 2013. Grafts with parallel faces. Purpose: avoid hyperopic shifts post DSAEK
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DSAEK GRAFTS WITH PARALLEL FACES : IS THE FUTURE?Luca AvoniIV ivis suite user meeting Innsbruck, 6 July 2013
Grafts with parallel faces • Purpose: • avoid hyperopic shifts post DSAEK • obtain a thin graft with a uniform thickness from one side to the other in order to reduce the incidence of post-operative detachment
Retrospective observational study 15 donor corneas not suitable for transplantation, for morphological abnormalities or donor is not suitable for medical history, according to the following protocol : Corneal pachymetry with corneal optical tomography Setting pachymetry to a constant thickness of 550 um with excimer laser Acquisition of corneal pachymetry Cut of stromal flap with microkeratome for a thickness of 400 um Acquisition of corneal pachymetry Histological analysis of the cross section of stromal and endothelial flap
Retrospective observational study: Instruments Optical tomography Software for customized ablation. Excimer laser. Microkeratome Ophthalmic microscope
Retrospective observational study Software for the regularization of the corneal stroma to a desired thickness by a customized ablation with excimer laser
OBJECTIVES: • Realization of stromal lenticule with uniform thickness of 550 μ by a customized ablation with excimer laser • Realization of endothelial lenticule with uniform thickness of 150 µ • To evaluate the safety and effectiveness of this procedure
Step 1 Evaluation of the cornea by microscope according to the traditional criteria of the EYE Bank (cell density, margins, morphology and mortality) ITER
Step 2 Optical Corneal tomography with and study of the pachymetry map with high repeatability ITER
STEP 3 Set up a Customized ablation to regularize the stroma to a constant residual thickness of 550 microns ITER
STEP 4 Customized ablation with laser in order to obtain a regular stroma lenticule of 550 microns thickness ITER
STEP 5 Optical corneal tomography to assess the pachymetry ITER
ITER STEP 6Cut of the stromal flap with a microkeratome 400 micron-head to obtain a endothelial lenticule of 150 micron thickness.
ITER STEP 7Pachymetry of endothelial lenticule. Thickness of stromal lenticule is obtain by the difference between the pre-cut pachymetry and post-ablation pachymetry. Optical Pachimetry after the 400 microns cut with microcheratomy of the endothelium lenticule Pachimetry[ µ ] N=13 Target 150 ±50 µ Left point Center point Right point Mean 142.1 156.05 170 σ CI 95% 1.82 141.11 143.09 3.202 154.31 157.79 5.56 166.98 173.02
ITER STEP 8Evaluation of the endothelial lenticule by microscope according to the traditional criteria of the EYE Bank (cell density, margins, morphology and mortality)
ITER STEP 9Histological evaluation of endothelial lenticule (thickness and morphology)and the stromal lenticule (thickness and morphology.)
CONCLUSIONS This clinical study showed that the procedure of regularization of the cornea thickness with the excimer laser IRES is effective and safe as shown in the following endpoints.
Histological evaluation • Paraffin embedding • Staining with hematoxylin and eosin • Scanner digital slides • Measurement with morphometro
CONCLUSIONS Endpoint 1 –Stromal regularization: The pachymetry after the customized ablation of the stromal lenticule has shown that the average thickness of 550 ± 25 micron has been achieved successfully
CONCLUSIONS Endpoint 2 – Endothelial lenticule: The pachymetry after the microkeratome cut of the endothelial lenticule has shown that the average thickness of 150 ± 50 micron has been achieved successfully In addition to optical pachymetry, histological analysis, performed at the Pathology Department of Ospedale Maggiore-Bologna in October 2012, provided a further confirmation of the results.
CONCLUSIONS Endpoint 3 – Stromal Lenticule: The difference between the pachymetry performed before and after the customized ablation of the stromal lenticule has shown that the average thickness of 400 ± 50 micron has been achieved successfully. The histological analysis has shown in this last case a stromal lenticule of 508,7 μm thickness of the left side, 522,7 μm of the center and 540,1 μm of the right side. Probably, this inconsistency is due to the delay of more than four months from the date of execution of the procedure and the date of execution of the histological analysis.