[Experimental corneal imaging and corneal surgery with non-amplified femtosecond laser pulses]

Non-amplified femtosecond laser was used to induce multiphoton effects for corneal tissue imaging and for tissue ablation.A non-amplified titanium-sapphire laser was coupled to a laser scanning microscope in order to examine human and porcine cornea. Tissue was subjected to imaging and lesions were created using identical optical pathways at pulse energies below 2 nJ.Cellular components and the extracellular matrix were selectively imaged by applying autofluorescence and second harmonic generation at submicron resolution. Intrastromal linear scanning at higher power resulted in luminescent plasma along the scanning line. Lesion width decreased with increasing tissue depth and increased with increasing laser power at the target. Light microscopy showed intact stromal tissue around the area of the lesion.High-resolution images as well as high precision tissue lesions were created in the cornea using low energy femtosecond laser pulses. Easy switching between tissue imaging and ablation seems to be suitable for diagnostic and therapeutic applications.