Diode Laser Welding in Femtosecond Laser–Enabled Keratoplasty: Microscopic Characterization and Evaluation of Wound Strength
Purpose
To evaluate the effect of diode laser welding on wound strength in corneas cut with femtosecond laser Zig-Zag pattern and characterize the microscopic changes.
Methods
Ten eye bank corneoscleral rims were cut using the Intralase femtosecond laser in a 9.5 mm Zig-Zag configuration. Following the placement of 8 interrupted 10-0 nylon sutures, a saturated indocyanine green (ICG) solution was applied into the wound interface. The ICG-stained wound edges were irradiated using a 25 gauge endoprobe connected to a 810 nm diode laser emitting at low power (60 mW). Wound burst pressure was evaluated before and after laser welding. Laser welded corneas were then sectioned and examined using high magnification light microscopy and second harmonic generation (SHG) imaging microscopy.
Results
There was no statistically significant difference in wound burst pressure before (24.9 +/- 13.9 mmHg) and after laser welding (28.9 +/- 9.1 mmHg, p=0.76). Fragility of the wound interface was also observed during tissue sectioning. High magnification microscopy and SHG imaging of laser welded corneas showed ICG uptake at the wound edges, irregular stromal melt at the wound interface, and tissue disruption.
Conclusion
While diode laser welding does result in stromal melt and uptake of ICG in cadaver corneas pre-cut with the femtosecond Zig-Zag incision, it does not add significant mechanical stability to the wound.