Proceedings Article | 18 January 2011
KEYWORDS: Laser ablation, Polymers, Excimer lasers, Polymethylmethacrylate, Intraocular lenses, Scanning electron microscopy, Ultraviolet radiation, Atomic force microscopy, Pulsed laser operation, Silicon
The use of intraocular lenses (IOL) is the most promising method for restoring excellent vision in cataract surgery. In
addition, multifocal intraocular lenses for good distant and near vision are investigated. Several new materials,
techniques and patterns are studied for the formation and etching of intraocular lenses in order to improve their optical
properties and reduce the diffractive aberrations. As pulsed laser ablation is well established as a universal tool for
surface processing of organic polymer materials, this study was focused in using laser ablation with short and ultra short
laser pulses for surface modification of PMMA and intraocular lenses, instead of using other conventional techniques.
The main advantage of using very short laser pulses, e.g. of ns, ps or fs duration, is that heat diffusion into the polymer
material is negligible. As a result high precision patterning of the sample, without thermal damage of the surroundings,
becomes possible.
In this study, laser ablation was performed using commercially available hydrophobic acrylic IOLs, hydrophilic acrylic
IOLs, and PMMA IOLs, with various diopters. We investigated the ablation efficiency and the phenomenology of the
etched patterns by testing the ablation rate, versus laser energy fluence, at several wavelengths and the surface
modification with atomic force microscopy (AFM), or scanning electron microscopy (SEM). The irradiated polymers
have different optical properties, at the applied wavelengths, and therefore, present different ablation behaviour and
morphology of the laser ablated crater walls and surrounding surfaces. The experimental results, some theoretical
assumptions for mathematical modeling of the relevant ablation mechanisms are discussed.
