Abstract
Purpose :
To evaluate the results of three different Bowman layer (BL) graft preparation methods: manually (m-BL), femtosecond laser-assisted (fs-BL), and by femtosecond laser followed by excimer laser (fs/ex-BL).
Methods :
Descemet membrane-denuded donor corneas (n=41) were used for this study, 2 corneas for m-BL graft, 18 corneas for fs-BL graft and 21 corneas for fs/ex-BL. For fs-BL, the corneas were placed on an artificial anterior chamber and different depth cuts were performed with decreasing increments starting from 30 µm, diameter 9.0 mm. For fs/ex-BL graft preparation, a superficial flap thickness of 80 µm was created by the femtosecond laser (FEMTO LDV Z8, Ziemer). Subsequently, the graft was placed stromal side up and the residual stroma was ablated by the excimer laser (Schwind Amaris 750S) with increasing increments starting from 40 µm. Grafts were analyzed visually and graft thickness regularity was evaluated by histological analysis.
Results :
Fs-BL preparation was successful using 30, 20, 15 and 14 µm cuts (success rate: 12 out of 14, 86%). Fs/ex-BL graft preparation was most successful after an 80 µm cut by femtosecond laser with subsequent 60 µm ablation by excimer laser (success rate: 15 out of 21, 71%). Immediately after the femtosecond laser flap, stripes were visible on the treated surface of the flap which were sometimes still visible after excimer laser ablation. Fs/ex-BL grafts were more transparent and less visible in fluid compared to fs-BL or m-BL.
Fs-BL grafts prepared at 14 µm depth were smoother and seem to resemble the thickness of m-BL grafts based on histological analysis. Compared to fs-BL and fs/ex-BL grafts, m-BL grafts showed long fibers protruding from the graft. Macroscopically, laser prepared grafts resembled manually prepared grafts.
Conclusions :
It is feasible to prepare thin, regular BL grafts by femtosecond and by femtosecond followed by excimer laser and these grafts were smoother than m-BL grafts. Fs and fs/ex-BL preparation may therefore be an alternative to manual BL graft preparation.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.