Femto-Masking
Femto-Masking offers an elegant solution to non-invasively generate small apertures in IOLs, using a femtosecond laser system. By applying a certain configuration of laser pulses (energy, spot size, spot distance, repetition rate) depending on the lens material, a photo chemical reaction can be induced which makes the material optically impermeable (blackening).
Mechanism of Action
With the use of ultrashort laser pulses, it is possible to induce nonlinear absorption of the laser light in originally transparent materials or tissue via multiphoton processes. This process is known as photodisruption, where a plasma is generated which locally disrupts the material. The disruption effect is used in corneal surgery (preparation of flaps, tunnels and lenticules) and laser assisted cataract surgery.
At laser intensities slightly below threshold for photodisruption, only a few free electrons are generated by the laser light, which induce photochemical reactions without any disruptive effect. This means that only the chemical properties of the irradiated material can be permanently changed, with local control.