Femtosecond Laser Deep Anterior Lamellar Dissection for DALK and DSAEK
Narrative Responses:
Purpose
Identify and optimize the parameters for smooth femtosecond deep anterior lamellar corneal dissection to be used in deep anterior lamellar keratoplasty (DALK) and in preparation of tissue for Descemet stripping automated endothelial keratoplasty (DSAEK)
Methods
Thirty human cornea-scleral rims were mounted on an artificial anterior chamber. Lamellar cuts close to Descemet's membrane were performed with a 150 kHz femtosecond laser (iFS IntraLase, Abbott Medical Optics, Santa Ana, CA) with a range of energy from 0.2 to 2.5 microJoules. Single pass and up to 8 multiple passes, consisting of spiral, raster, and combined patterns were made. A flat applanating and a curved applanating interface were compared. Direct observation of the ease of tissue separation and the gross appearance were recorded and the tissues were processed for scanning electron microscopy.
Results
A single pass requires energy levels above 1.5 microJoules to achieve separation and consistently resulted in an irregular surface with a flat or a curved applanating interface. In contrast, multiple passes at low energy (0.3 to 0.45 microjoules) resulted in a markedly smoother surface. A raster pattern was usually smoother than a spiral pattern. For most corneas, 6 passes, each rotated 45 degrees relative to the previous pass, yielded the best tissue separation. A curved compared to flat applanation interface resulted in no difference.
Conclusion
The femtosecond laser can achieve smooth deep anterior corneal lamellar dissection utilizing specific parameters. This technique may be useful in both DALK and in donor tissue preparation for DSAEK. Clinical trials are required to evaluate the optical performance compared to other techniques.