What is a femtosecond laser?

A femtosecond laser is an infrared laser that works at a wavelength of 1.052 nm. It emits ultrashort laser pulses with a diameter of 0.001 mm at one-billionth of a second (10^-15 s). With the femtosecond laser, tissue can be cut very precisely and with practically no heat development. The laser pulses deploy their energy at an exactly defined depth inside the cornea.

How does the femtosecond laser work?

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(1) Each laser pulse creates a mini-gas bubble (diameter of 1 µm). (2) A larger mini-gas/water bubble of approx. 5 - 12 µm diameter appears and separates the surrounding corneal tissue (photodisruption). (3) The emerging mixture of CO₂ and water is aspirated, leaving the separated corneal tissue behind. (4) Three-dimensional, high-precision laser cuts are created within the cornea by placing thousands of computer-positioned laser pulses next to each other.

The use of femtosecond laser technology in ophthalmology

In ophthalmology, the femtosecond laser is primarily used for flap creation prior to LASIK (Femto-LASIK or iLASIK) to correct nearsightedness and farsightedness with or without astigmatism. The new INTRACOR^® procedure uses the femtosecond laser to change the refraction of the cornea without any corneal incision.
Other uses include the preparation of corneal tunnels for intracorneal ring segment (ICRS) implantation, astigmatic keratotomy for the correction of higher astigmatisms and corneal transplant surgery (penetrating keratoplasty).

Advantages of the femtosecond laser

The femtosecond laser guarantees more stable corneal flaps with improved wound healing and higher biomechanical stability. By using the femtosecond laser, cut-induced complications such as free flaps or "button holes" are avoided, resulting in a safer procedure.

A femtosecond laser cut flap shows a homogeneous, high-quality stromal bed with clean edges.

Flap comparison: (1) femtosecond laser versus (2) microkeratome

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(1) The femtosecond laser creates thin, planar flaps with a uniform mean thickness (average standard deviation of as little as 4 μm within each flap).
(2) The microkeratome does not produce an even flap cut.