Multiphoton scaling of femtosecond laser-induced refractive index change (LIRIC) in hydrogels and rabbit cornea.

To find optimal conditions for performing laser induced refractive index change (LIRIC) in living eyes with both safety and efficacy, we investigated multiphoton excitation scaling of this procedure in hydrogel and excised corneal tissue. Three distinct wavelength modalities were examined: high-repetition-rate (HRR) and low-repetition-rate (LRR) 405 nm systems, as well as 800 nm and 1035 nm systems, whose LIRIC-inducing properties are described for the first time. Of all the systems, LRR 405 nm-LIRIC was able to produce the highest phase shifts at the lowest average laser powers.

Blue-LIRIC in the rabbit cornea: efficacy, tissue effects, and repetition rate scaling.

Laser-induced refractive index change (LIRIC) is being developed as a non-invasive way to alter optical properties of transparent, ophthalmic materials including corneas and . This study examined the optical and biological effects of blue-LIRIC (wavelengths 400-405 nm) of rabbit corneas. Following LIRIC treatment at low and high repetition rates (8.

Modification of surface morphology of hydrogels due to subsurface femtosecond laser micromachining.

In this paper, we studied the effects of subsurface femtosecond laser micromachining on surface morphology in hydrogels. Depending on material properties and writing conditions, we found surface bumps when materials were hydrated, and trenches when they were dehydrated, which can be attributed to the localized change in water concentration. Such wavy surfaces by laser-induced refractive index change are not desirable in clinical contact lenses.

Directional phase-unwrapping algorithm and phase shift technique on hydrogel.

Refractive index microstructures, which can be written by multiphoton absorption with femtosecond lasers, have many applications. Here we present a directional phase-unwrapping algorithm with phase-shifting technique and apply it to the metrology of hydrogel microstructures. A staircase phase-unwrapping algorithm is demonstrated.

Temporal evolution of the biological response to laser-induced refractive index change (LIRIC) in rabbit corneas.

Laser-induced refractive index change (LIRIC) is a new, non-incisional, non-ablative, femtosecond photo-modification technique being developed for vision correction in humans. Prior, exvivo studies showed intra-tissue refractive index change to induce minimal cell death, restricted to the laser focal zone in the corneal stroma, and with no observable damage to the epithelium or endothelium. Here, we used live rabbits to ascertain longer-term consequences of LIRIC in vivo.