Wavelength Optimization in Femtosecond Laser Corneal Surgery
Abstract
PURPOSE. To evaluate the influence of wavelength on penetration depth and quality of
femtosecond laser corneal incisions in view of optimizing procedures in corneal surgery
assisted by ultrashort pulse lasers.
METHODS. We performed penetrating and lamellar incisions on eye bank corneas using several
ultrashort pulse laser sources. Several wavelengths within the near-infrared and shortwaveinfrared
wavelength range were used and the pulse energy was varied. The corneas were
subsequently analyzed using light microscopy as well as transmission and scanning electron
microscopy.
RESULTS. We found higher penetration depths and improved incision quality when using
wavelengths close to k ¼ 1650 nm rather than the wavelength of k ¼ 1030 nm typical in
current clinical systems. Optical micrographs show an improvement of the penetration depth
by a factor of 2 to 3 while maintaining a good incision quality when using the longer
wavelength. These results were confirmed with micrographs obtained with transmission and
scanning electron microscopy.
CONCLUSIONS. A wavelength change from the standard 1030 nm to 1650 nm in corneal surgery
assisted by ultrashort pulse laser considerably reduces light scattering within the tissue. This
results in a better preservation of the laser beam quality in the volume of the tissue,
particularly when working at depths required for deep lamellar or penetrating keratoplasty.
Using this wavelength yields improved penetration depths into the tissue; it permits use of
lower energies for any given depth and thus reduces unwanted side effects as thermal effects.