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Roger Steinert, Marjan Farid, Sumit Garg, Matthew Wade; Femtosecond Laser "Mini-Bubble" Deep Lamellar Dissection for DALK and DSAEK. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3100.
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© ARVO (1962-2015); The Authors (2016-present)
To better define the parameters of femtosecond laser deep anterior lamellar dissection that result in a smooth bed for either deep anterior lamellar keratoplasty (DALK) or for preparation of donor material in thin stroma descemet stripping automated endothelial keratoplasty (DSAEK)
10 fresh human corneal scleral donors were mounted on artificial anterior chambers and exposed to femtosecond laser dissections 30-50 microns anterior to Descemet membrane using an iFS 150 kHz laser (Abbott Medical Optics, Santa Ana, CA). Variables studied were spot separation, pattern of laser scanning, and pulse energy. Key outcomes were 1) ease of tissue separation; 2) gross inspection of the tissue bed; 3) spectral domain optical coherence tomography (OCT); and 4) trypan blue/alizarin red staining of the endothelium.
Separation of the tissue plane was easiest with a combination of close spot separation (4x4 microns) and high pulse energy (3.5 microjoules). The smoothest bed was obtained with wide pulse spacing (10x10 microns); low pulse energy just higher than threshold (0.4 5 to 0.6 microjoules) and 8 alternating raster and spiral passes, rotated 45 degrees between each pair of passes. OCT revealed stromal separation either at or slightly anterior to Descemet membrane. Staining showed no evidence of endothelial injury.
Wide pulse spacing and very low pulse energy delivered in multiple passes results in a smoother stromal plane in the deep cornea, compared to tight spot spacing and higher pulse energy levels. This "mini-bubble" technique may be useful in both DALK and in donor tissue preparation for DSAEK.
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