Ultrashort pulse laser surgery of the cornea and the sclera

Abstract

The strongly localized interaction process of ultrashort laser pulses with tissue makes femtosecond lasers a powerful tool for eye surgery. These lasers are now routinely used in refractive surgery and other forms of surgery of the anterior segment of the eye. Several clinical laser systems also offer options for corneal grafting and the potential use of ultrashort pulse lasers in glaucoma surgery has been the object of several recent studies which have shown promising results. While devices aimed for interventions in clear tissue may be based on available solid state or fibre laser technology, the development of tools for surgery in more strongly scattering tissue has to account for the compromised tissular transparency and requires the development of optimized laser sources. The present paper focuses on surgery of clear and pathological cornea as well as sclera. It aims to give an overview over typical medical indications for ultrashort pulse laser surgery, the optics of the tissues involved, the available laser technology, the laser–tissue interaction process, and possible future developments.

Wavelength dependence of femtosecond laser-induced breakdown in water and implications for laser surgery

“…Recently UV-A pulses have been employed for flap cutting in corneal refractive surgery because the shorter wavelengths provides a better cutting precision due to the shorter plasma length [55][56][57][58]134] Furthermore, the collagen molecules in corneal tissue act as stable centers of reduced excitation energy in UV breakdown that lower the breakdown threshold and minimize mechanical side effects [58]. On the other hand, the wavelengths considerably longer than 1040 nm have been tested for plasma-mediated surgery in strongly scattering tissues such as sclera, skin and brain [59][60][61]63] and in edematous corneas [64].…”

Underwater acoustic signals induced by intense ultrashort laser pulse

“…Investigation of energy deposition in water from ultrashort laser pulses has attracted considerable interest in the last decade in view of potential applications ranging from laser surgery, 1,2 to triggering of high voltage water switches, 3 or remote generation of acoustic sources. [4][5][6] It has been recognized early on that an intense laser pulse focused in a transparent liquid can heat or ionize the medium, leading to the emission of an acoustic transient.…”

Extending the binary collision algorithm to non-Spitzer systems and application to laser heating and damage

“…Elucidating these dynamics is a crucial step for the study of laser generated warm dense matter and laser induced surface modification and damage [1][2][3][4][5][6]. In particular, a better understanding is important for optimizing applications of ultrashort (sub-ps), ultra-intense (> 10 12 W/cm 2 ) laser driven surface modification which includes laser surgery, laser machining and characterization, creation of hydrophobic surfaces, solar cell enhancement and many others [7][8][9][10][11][12][13]. For laser pulses achieving relativistic intensities (approximately 10 18 W/cm 2 for near-infrared lasers), this physics is germane as well since the initial heating that occurs on the leading edge of the laser pulse at much lower intensities determines the nature of the surface once the peak of the pulse arrives.…”