Laser to modify IOL

California-based company Perfect Lens has developed a new approach to the postoperative adjustment of an intraocular lens (IOL) that involves using a femtosecond laser to change the refractive index of the lens material, said Josef Bille PhD, Professor of Physics at University of Heidelberg, Germany, and Perfect Lens LLC’s Vice President, at the XXXIII Congress of the ESCRS in Barcelona, Spain.

Dr Bille noted that the process, called refractive index shaping, causes a change of the hydrophilicity within the lens, which in turn causes a negative refractive index change in the targeted region of the lens. In this way, it is possible to create a lens within a lens with range of possible optical properties, including asphericity and toricity, which can be finely adjusted postoperatively within the patient’s eye.

Dr Bille noted that they have used the system for a new phase wrapping process, whereby they create a custom Fresnel-like lens in a 50μm-thick layer within a standard acrylic hydrophobic IOL (EC-1Y, Zeiss). In experiments with their current prototype they have been able to induce changes of up to five dioptres in a predictable fashion with minimal change to the IOL’s modular transfer.

The Perfect Lens system includes an infrared femtosecond laser (Mai Tai HP, Spectra-Physics) and an acousto-optic modulator (Gooch and Housego) to provide pattern shaping and modulate the laser energy of the beam. The system also includes a 2D scan system (Newson), ultra-precise 3D linear motor set-up and a high numerical aperture microscope and a Nimo 0815 (Perfect Lens) wavefront analyser to measure spherical aberration, modular transfer function and dioptric power.

​CUSTOM ASPHERICITY

Through this process they have been able to induce spherical aberration changes from -0.27μm to +0.28μm in a standard IOL. The internal lens-shaping process takes only five seconds, reported Ruth Sahler MSc, Perfect Lens LLC Vice President and COO.

She added that, although the experiments were carried out in a laboratory setting, the lens modifications were performed in a manner which complies with applicable laser safety regulations. She and her associates are now in the process of developing an interface for use in humans, and animal trials are likely to start soon.

“Our goal is to use the hydrophilicity based refractive index shaping technology to create customised, premium IOLs and to improve the outcome of patients after cataract surgery,” Ms Sahler said.

Josef Bille: josef.bille@urz.uni-heidelberg.de

Ruth Sahler: rsahler@perfectlens.com