This PDF file contains the front matter associated with SPIE Proceedings Volume 7373, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

We present our results for nanoparticle mediated laser poration as an alternative transfection technique. As a fundamental part for the perforation of the cell membrane the interactions of gold nanoparticles and living cells were studied.

Cloning of several mammalian species has been achieved by somatic cell nuclear transfer (SCNT) in recent years. However, this method still results in very low efficiencies around 1% which originate from suboptimal culture conditions and highly invasive techniques for oocyte enucleation and injection of the donor cell using micromanipulators. In this paper, we present a new minimal invasive method for oocyte imaging and enucleation based on the application of femtosecond (fs) laser pulses. After imaging of the oocyte with multiphoton microscopy, ultrashort pulses are focused onto the metaphase plate of MII-oocytes in order to ablate the DNA molecules. We show that fs laser based enucleation of porcine oocytes completely inhibits the first mitotic cleavage after parthenogenetic activation while maintaining intact oocyte morphology in most cases. In contrast, control groups without previous irradiation of the metaphase plate are able to develop to the blastocyst stage. Further experiments have to clarify the suitability of fs laser based enucleated oocytes for SCNT.

Selective retina treatment (SRT) is a laser based therapy of retinal diseases associated with disorders of the retinal pigment epithelium (RPE) while preserving photoreceptors and choroid. Microsecond laser pulses applied to the 100-200 strongly absorbing melanin granules inside the RPE cells induce transient micro bubbles which disrupt the cells. Aim of this work is to understand bubble dynamics in clusters. Investigations were carried out on porcine RPE explants and on a floppy disc based model system. Laser pulse durations of 3 ns (532 nm, Nd:YAG) and 1.7 μs (527 nm, Nd:YLF) were used. Bubble dynamics was explored with a fiber interferometer (830 nm) and fast flash photography (25 ns). Bubble sizes, velocities and lifetimes were measured. Single nucleation sites, which coalesce after some μs, are observed with ns pulses. Using μs pulses, fewer but larger cluster sites are observed which become two times bigger at the same factor above threshold. A linear increase of the bubble hight with radiant exposure is found for both pulse durations. RPE Bubble formation thresholds of 85 mJ/cm² and 255 mJ/cm² for ns and μs pulses are found, respectively. Typical expansion velocities are 5 m/s while collapsing bubbles can reach 30 m/s. Bubble heights are up to 5 μm. Earlier investigations on single melanosomes showed a bubble size limitation to 4 μm with μs pulses. The melanosome clusters do not show this size limit. It has to be investigated whether the results are transferable to whole eye globes.

The retinal photocoagulation is an established treatment method for different retinal diseases. The extent of the thermal coagulations depends strongly on the generated temperature increase. Until now the dosage is based on a pool of experience of the treating physicians as well as the appearance of the whitish lesions on the retina. The temperature course during photocoagulation can be measured in real-time by optoacoustics. A frequency-doubled Q-switched Nd:YLF laser (523nm, 75 ns) is used for optoacoustic excitation and a continuous-wave Nd:YAG laser (532nm) with adjustable irradiation time and power for heating of the fundus tissue. The onset of coagulation is determined by a photodiode that is placed directly behind enucleated porcine eyes, which served as a model. The onset of coagulation is observed clearly when scattering sets in. The required power for coagulation increases exponentially with decreasing irradiation time. The first results on rabbit eyes in vivo indicate that the onset of coagulation defined by just barely visibile lesions at a slit lamp sets in at an ED50 threshold temperature of 63°C for an irradiation time of 400 ms. In conclusion, optoacoustics can be used to determine temperatures during retinal laser treatments in real-time. This allows evaluating the time-temperature-dependence of retinal coagulation in vivo.

Presbyopia is an age related effect which affects every human at the age of about 40 years. So far reading glasses are the conventional treatment. According to Helmholtz' theory of accommodation one of the mayor reasons for the development of presbyopia is the increasing sclerosis of the lens. In contrast to that the ciliary muscle and the lens capsule remain mostly active and elastic the whole life. So a possible treatment could be the increase of the flexibility of the lens by creating gliding planes with fs-laser pulses inside the lens tissue. In former studies it was shown that fs-laser pulses were able to increase the flexibility of ex vivo porcine lenses as well as ex vivo human donor lenses. Our current aim was to evaluate the effect of the fs-laser pulses on the crystalline lens of living rabbit eyes due to the fs-lentotomy treatment. The main focus of the evaluation was the exclusion of possible side effects of the treatment like cataract formation or retina damage. The treated eyes were monitored using optical coherence tomography (OCT) and Scheimpflug imaging for localizing and studying the tissue effects of the incisions. Furthermore histological sections of the lens and retina were prepared. The rabbits were investigated pre operatively and up to six months post operatively. The fs-laser induced micro incisions were successfully applied to the left lens of each rabbit. The micro incisions within the crystalline lens were detectable with OCT and Scheimpflug imaging up to six month. The imaging within the lens showed a progressive fading of the incisional opacities generated by the femtosecond laser during the six months and no indication of cataract formation was found. OCT and Scheimpflug images emphasize themselves as necessary tools to monitor the micro incisions over time. Histopathological sections of the lens tissue support the findings of the non invasive imaging techniques. Also the histopathological sections of the retina show no thermal induced change due to the irradiation of the fs-pulses.

Photobleaching of a 58 year old human donor lens was demonstrated using an infra-red, femtosecond Ti:Sapphire laser. Pulse duration was 300 femtoseconds, pulse energy was 0.1 μJ, and the focal spotsize of the laser was approximately 14 μm in diameter. The lens was treated in a 1x1 mm large area by scanning the laser beam. Significant photobleaching was seen after laser treatment. Light transmission increased by 7%. The greatest effect was seen in the blue-green part of the visible spectrum.

Femtosecond laser surgery in the volume of corneal tissue is difficult in the case of oedematous or pathological corneas: in those corneas, the propagation of the laser beam is perturbed by the optical scattering. This phenomenon can be greatly reduced by using a better suited laser wavelength. A series of ex vivo surgical experiments has been conducted at wavelengths around 1600 nm. The results have been compared to experiments performed at 800 nm and 1000 nm. We have compared penetration depth and incision quality as a function of wavelength and energy.

The extent of retinal laser coagulations depends on the temperature increase at the fundus and the time of irradiation. Due to light scattering within the eye and variable fundus pigmentation the induced temperature increase and therefore the extent of the coagulations cannot be predicted solely from the laser parameters. We use optoacoustics to monitor the temperature rise in real-time in vivo (rabbit) and ex vivo (porcine eye) and to automatically control the coagulation strength. Continuous wave treatment laser radiation and pulsed probe laser light (1-1100 ns) are coupled into the same fibre and are imaged onto the retina by a laser slit lamp. The temperature dependent pressure waves are detected by an ultrasonic transducer embedded in a customary contact lens. Below the coagulation threshold the increase in acoustic amplitude due to thermal tissue expansion is up to 40 %. Best signal to noise ratios > 10 are achieved with probe pulse durations of 1 to 75 ns. Further a time critical algorithm is developed which automatically ceases laser treatment when a certain preset coagulation strength is achieved. Coagulations with similar extent are obtained with this method in vitro and in vivo even when varying the power of the treatment laser by 50 %. These preliminary results are very promising, thus this method might be suitable for an automatic feedback controlled photocoagulation with adjustable coagulation strength.

A prominent laser based treatment in ophthalmology is the LASIK procedure which nowadays includes a cutting of the corneal tissue based on ultra short pulses. Focusing an ultra short laser pulse below the surface of biological tissue an optical breakdown is caused and hence a dissection is obtained. The laser energy of the laser pulses is absorbed by nonlinear processes. As a result a cavitation bubble expands and ruptures the tissue. Hence positioning of several optical breakdowns side by side generates an incision. Due to a reduction of the duration of the treatment the current development of ultra short laser systems points to higher repetition rates in the range of hundreds of KHz or even MHz instead of tens of kHz. This in turn results in a probable occurrence of interaction between different optical breakdowns and respectively cavitation bubbles of adjacent optical breakdowns. While the interaction of one single laser pulse with biological tissue is analyzed reasonably well experimentally and theoretically, the interaction of several spatial and temporal following pulses is scarcely determined yet. Thus the aim of this study is to analyse the dynamic and interaction of two cavitation bubbles by using high speed photography. The applied laser pulse energy, the energy ratio and the spot distance between different cavitation bubbles were varied. Depending on a change of these parameters different kinds of interactions such as a flattening and deformation of bubble shape or jet formation are observed. Based on these results a further research seems to be inevitable to comprehend and optimize the cutting effect of ultra short pulse laser systems with high (> 1 MHz) repetition rates.

A localized X-ray source for the pin-point treatment of cancers using femto-second laser has been developed. Particular emphasis is put on i) stable emission of X-rays, ii) a sufficient dose and iii) a sufficient photon energy for the treatment. Almost 80 % of the objectives listed above has been realized and the first X-ray irradiation test on cancer cells shows a significant effect on the cancer DNA.

Properties of spectral fluctuations and prominent spectral features of fluorescence spectra in visible region using laser as an excitation source of normal, benign and cancer human breast tissues are studied through wavelet transform and principal component analysis.

Laser Doppler flowmetry (LDF) signals give a peripheral view of the cardiovascular system. To better understand the possible modifications brought by sleep apnea syndrome (SAS) in LDF signals, we herein propose to analyze the complexity of such signals in obstructive SAS subjects, and to compare the results with those obtained in healthy subjects. SAS is a pathology that leads to a drop in the parasympathetic tone associated with an increase in the sympathetic tone in awakens SAS patients. Nine men with obstructive SAS and nine healthy men participated awaken in our study and LDF signals were recorded in the forearm. In our work, complexity of LDF signals is analyzed through the computation and analysis of their multifractal spectra. The multifractal spectra are estimated by first estimating the discrete partition function of the signals, then by determining their Renyi exponents with a linear regression, and finally by computing their Legendre transform. The results show that, at rest, obstructive SAS has no or little impact on the multifractal spectra of LDF signals recorded in the forearm. This study shows that the physiological modifications brought by obstructive SAS do not modify the complexity of LDF signals when recorded in the forearm.

Staphylococci are important causes of nosocomial and medical-device-related infections. Their virulence is attributed to the elaboration of biofilms that protect the organisms from immune system clearance and to increased resistance to phagocytosis and antibiotics. Photodynamic treatment (PDT) has been proposed as an alternative approach for the inactivation of bacteria in biofilms. In this study, we evaluated the antimicrobial activity of merocyanine 540 (MC 540), a photosensitizing dye that is used for purging malignant cells from autologous bone marrow grafts, against Staphylococcus epidermidis biofilms. We evaluated the effect of the combined photodynamic action of MC 540 and 532 nm laser on the viability and structure of biofilms of two Staphylococcus epidermidis strains. Significant inactivation of cells was observed in the biofilms treated with MC-540 and then exposed to laser radiation. Furthermore we found that the PDT effect, on both types of cells, was significantly dependent on both the light-dose and on the impinging lightintensity. Disruption of PDT-treated biofilm was confirmed by scanning electron microscopy (SEM).

Photodynamic Therapy (PDT) provides a non-invasive, efficient and safe treatment for skin diseases with good cosmetic results. These characteristics make this technique more advantageous than radiotherapy or chemotherapy, which present limitations in a big number of lesions, are painful in many cases and produce non-satisfactory cosmetic results. We present the clinical results obtained at present by this optical technique and a photochemical model of the PDT process applied to the skin by means of a topical photosensitizer, in order to find the optimal PDT parameters. Optical propagation inside the tissue is calculated by means of the three dimensional Beer-Lambert law, due to its facility to be integrated in the differential equations system used to model the photochemical processes involved. With this information it is possible to obtain an initial estimation about the optimal drug dose and the optical power required.

Recent improvements in the computing power and programmability of graphics processing units (GPUs) have enabled the possibility of using GPUs for the acceleration of scientific applications, including time-consuming simulations in biomedical optics. This paper describes the acceleration of a standard code for the Monte Carlo (MC) simulation of photons on GPUs. A faster means for performing MC simulations would enable the use of MC-based models for light dose computation in iterative optimization problems such as PDT treatment planning. We describe the computation and how it is mapped onto the many parallel computational units now available on the NVIDIA GTX 200 series GPUs. For a 5 layer skin model simulation, a speedup of 277x was achieved on a single GTX280 GPU over the code executed on an Intel Xeon 5160 processor using 1 CPU core. This approach can be scaled by employing multiple GPUs in a single computer - a 1052x speedup was obtained using 4 GPUs for the same simulation.

Laser-induced thermo therapy (LITT) is an alternative, gentle therapy of cancer. In this work a new computational model (3D space and time) of LITT is presented. Using an arbitrary small number (< 20) of optical fibers, multiple low energy laser light sources are applied internal to an arbitrary shaped tumor in the human liver. The power and position of each source can be chosen arbitrary. Each source is a spherical point source emitting light isotropically. The model consists of two, semi-coupled partial differential equations (PDEs) describing the light distribution and the heat absorption in the target tissue. Since water is a dominant tissue component in both the healthy liver and the malignant tumor the wavelength of the laser is chosen in the NIR area (1,064 nm). This is expected to form an absorption contrast in favor of the tumor leading to high temperature and damage of the tumor cells. The new, fast computational model presented here opens for the possibility of evaluating the outcome of LITT by inspection of temperature fields, and comparing these to measured histological damage due to heating. This combination is promising when evaluating the result of LITT prior to the actual treatment.

Computer modeling can be a valuable tool to determine the absorption of laser light in different skin layers. For this study, the optical properties of three different skin tumors were used in the model to evaluate the effect on penetration depth into the skin. Comparison between the healthy dermis and the skin tumors indicated that up to 28 % more laser light is absorbed in the healthy dermis than in the tumor tissue. This has implications on the laser dose applied to the skin for treatment.

Poly(N-isopropylacrylamide) i.e. PNIPAAm is a temperature sensitive smart material which displays a lower critical solution temperature (LCST) at 33-35°C. At the lower critical solution temperature, the gel changes from hydrophilic to hydrophobic which has significant consequences in cell culturing. The first known measurements of the optical properties i.e. absorption (μ_a) and reduced scattering (μ'_s) coefficients, as a function of temperature, of a series of crosslinked PNIPAAm gels, using an Integrating Sphere setup, is presented at a wavelength of 632.8 nm. These properties showed a direct correlation between the scattering coefficient and the crosslinker density for the gels. The absorption properties correlated well with the known absorption characteristics of these gels.

The objective of this study was to optimize titanium surfaces by means of Ti:Sapphire femtosecond laser to improve the attachment of human cartilage cells on titanium prosthesis in middle ear surgery. The application of microstructures on titanium samples was evaluated and the influence of these microstructures on human auricular chondrocytes was studied in-vitro. After establishing the ear chondrocyte cell culture, cells were seeded on titanium platelets with selected microstructure patterns. Whereas the phenotype of cells seeded on unstructured titanium was similar to cells grown on standard tissue culture surfaces, the morphology of chondrocytes grown on structured titanium samples was influenced by the pattern. For future titanium middle ear prosthesis structural optimizations will be developed to promote chondrocyte growth and adhesion while impeding fibrocyte proliferation to avoid scarring on implant interfaces.

A cw Laser system (Medical Laser Centre Lübeck GmbH, Germany) emitting a wavelength at 1.92μm and a laser power up to 50 W was used for partial porcine renal parenchyma resection and hemi nephrectomy. Laser radiation (30 Watt) was transmitted via 365μm fiber with polished distal fiber tip which was fixed in a stainless steel tube. Power density at the distal fiber tip was 28.6 kW/cm2. On 3 kidneys a partial renal parenchyma resection without opening of the renal pelvis was performed (Group A). On 8 kidneys a hemi nephrectomy with opening of the renal pelvis was performed (Group B). Total resection time including haemostasis of the remaining tissue was 501 ± 103 s in group "A" and 730 ± 415 s in group "B". Blood lost was 28 ± 3 ml in group "A" and 98 ± 73 ml in group "B". The ischemic time for the kidneys in group "B" was 157 s in average, while for group "A" no ligation was necessary at all. Healing process was observed over 3 weeks, survival rate was 100 %, no inflammation or renal fistulas were found. In conclusion, the first experiments show that the 1.92 μm Laser-System is a very promising device for bloodless and fast kidney resection.

We present a study showing advantages of EVLT at 1.56 μm wavelength in comparison with 0.97 μm. In particular, the water and blood absorption at 1.56 μm give better EVLT conditions than at 0.81-1.5 μm.

XeCl excimer laser coronary angioplasty (ELCA), has gained more attention for the treatment of serious stenosis blocked by plaque. Low degrees of thermal damage after ablation of atherosclerotic plaques have been achieved by ELCA. However, the large number of risks associated with the procedure, for example, dissections or perforations of the coronary arteries limits its application. The laser treatment technique with high ablation efficiency but low arterial wall injury is desirable. Mid-infrared laser with a wavelength of 5.75 μm is selectively well absorbed in C=O stretching vibration mode of ester bonds in cholesteryl ester. We studied the effectiveness of nanosecond pulsed laser at 5.75 μm for novel less-invasive laser angioplasty. In this study, we used a mid-infrared tunable solid-state laser which is operated by difference-frequency generation, at 5.75 μm, a pulse width of 5 ns and a pulse repetition rate of 10 Hz as a treatment light source, and a thoracic aorta of WHHLMI rabbit as an atherosclerosis model. As a result, less-invasive treatment parameters for removing atherosclerotic plaques in a wet condition were confirmed. This study shows that the nanosecond pulsed laser irradiation at 5.75 μm is a powerful tool for selective and less-invasive treatment of atherosclerotic plaques.

In this paper the cytotoxic effect of m-THPC, Foscan®, as well as of the liposomal formulation of m-THPC, Fospeg®,(kind offer of Biolitec) were studied post PDT in the human prostate cancer cell line LNCaP. The cells were incubated for 24h with 0.15 μg/ml and 1.2 μg/ml Foscan® and Fospeg®. Irradiation was performed with a 652nm laser and energy doses 180, 360 and 540mJ/cm². The effect was assessed by the MTT viability test 24h after irradiation. Also the intracellular localization of Foscan® and Fospeg® was monitored by using Laser Scanning Confocal Microscopy Imaging. The results showed no dark toxicity either with Foscan® or Fospeg® at any concentration. Also irradiation at each energy dose in the absence of any photosensitizer, did not affect cellular viability. The cellular death caused after Photodynamic Treatment was dependent on m-THPC concentration and formulation, as well as the delivered energy dose. Fospeg® was more effective as LD50 was achieved with 0.15μg/ml at 180mJ/cm² while for the same cytotoxic result 1.2μg/ml Foscan® was needed. Images from confocal microscopy revealed higher fluorescence intensity in the cytoplasm after incubation with Fospeg®, than upon incubation with Foscan® under the same experimental conditions.

Photodynamic inactivation (PDI) of bacterial strains presents an attractive potential alternative to antibiotic therapies. Success is dependent on the effective accumulation in bacterial cells of photochemical substances called photosensitizers, which are usually porphyrins or their derivatives. The kinetics of porphyrin synthesis after treatment with the precursor ALA and the accumulation of the Chlorin e6 and the following illumination were studied. The goal was to estimate effectivity of the destructive power of these PS in vitro in respect of the physiological states of Mycobacteria. So the present results examine the cell destruction by PDI using ALA-induced Porphyrins and Chlorin e6 accumulated in Mycobacterium phlei and Mycobacterium smegmatis, which serve as models for the important pathogens Mycobacterium tuberculosis, Mycobacterium leprae and Mycobacterium bovis. We could show that both Mycobacterium after ALA and Chlorin e6 application were killed by illumination with light of about 662 nm. A reduction of about 97% could be reached by using a lightdose of 70 mW/cm².

An integrating cylinder composed of high-density polyurethane with a measured multiplication factor (M) of 38 has been developed for absolute calibration of fluence rate probes designed for monitoring of photodynamic therapy (PDT) and other light-based therapies.

Fluorescent multi-sensor fiber-optic probes for spatially resolvedmonitoring of Interstitial Photodynamic Therapy were absolute calibrated using an integrating cylinder. The dynamic response was evaluated and showed linear responsivity in the test range from 1 - 60 mW•cm^-2. Sensor-probe and optoelectronic readout provides an accuracy of better than 10%.

Optical Coherent Tomography (OCT) currently used for in-vivo tissue images is a high resolution information source about local optical properties of tissue. From OCT images analyzed we have extracted data about the light attenuation at 1350 nm. Sample used was dental implant with well known screw size. The results are in relatively good agreement with literature data obtained with classical methods. OCT image treatment to obtain optical data parameters has advantage of in-vivo measurements and high spatial resolution.

The mathematical model the hyperthermy of the multilayer biological structure under the effect of laser emission is proposed. One allows to variate the electrophysical parameters of the biological structure (complex parameter of refraction of the blood and blood corpuscles, epidermis, the upper layer of derma, the lower layer of derma), the significant dimensions of the regular elements of the blood and to establish dependencies between them and by the biophysical properties of the blood taking into account heating biological tissue under the influence on its surface flow of the nonpolarized monochromatic radiation for the case in vivo.

The use of endovenous laser treatment for varicose veins has been increasing in recent years. It is a safer technique than surgical vein stripping. Its complications (e.g. bruising, pain) are less than the complications of surgical vein stripping. But best parameters such as optimum wavelength, power, and application duration are still under investigation to clarify uncertainties about this technique. To prevent its complications and improve its clinical outcomes, the exact mechanism of it has to be known. The aim of this study is to investigate the effect of different laser wavelengths on endovenous laser therapy. In this study 980-nm diode laser and 1070-nm fiber laser were used. Human veins were irradiated with 980-nm and 1070-nm lasers at 8 W and 10 W to find the optimal power and wavelength. After laser application, remarkable shrinkage was observed. Inner and outer diameters of the veins also narrowed for both of the laser types. 10 W of 980-nm laser application led to better shrinkage results.

The method of laser osteoperforation was developed in experiment and then applied for treatment of 508 patients with osteomyelitis, 51 patients with nonunion and pseudo-joint and 34 patients with different forms of osteochondropathy. The clinical trial proved the efficiency of laser osteoperforation for treatment of both inflammatory and destructive bone diseases. This method is minimally invasive, promotes rapid reduction of bone and soft tissue inflammation, and apparently stimulates bone reparation.

This in vitro study was conducted in order to assess using optical microscopy the apical sealing in Nd:YAG laser irradiated root canals in comparison with the conventional treatment method.

Laser optical trapping and micromanipulation of microparticles or cells and subcellular structures have gained remarkable interest in biomedical research and applications. Several laser sources are employed for the combination of a laser scalpel with an optical tweezers device, under microscopic control. However, although the principles and the mechanisms of pulsed laser ablation have been well described for macroscopic interventions, the microbeam operation, under microscopic guidance, necessitates further experiments and investigations. We present experimental results of controlled micro-ablation of PMMA beads of 3-8 μm diameters, trapped by laser tweezers in various media e.g. solutes of different index of refraction. An optical tweezers system, based on a continuous wave He-Ne laser emitting at 632.8 nm, was tested on beads and, despite the low power of the He-Ne laser, the optical trap was stable. Another optical system, based on a cw Nd:YAG laser emitting at 1.06 μm, was tested on microspheres too. Successful beads ablation was carried out by irradiation with multiple, or even a single nitrogen laser pulse of 7 ns pulse duration at a wavelength of 337 nm. The ablative perforation of the microspheres was estimated by controlling the laser fluence. Moreover, shape deformations of PMMA microspheres were observed. The experimentally obtained results are theoretically explained via the spatial intensity distribution based on Mie light scattering theory. Furthermore, the appearance of laser ablation holes in the back side of microspheres is explained by the ablation triggered shock waves propagation. The role of the stretching forces action is also discussed. Additionally, we report experimental results on measuring the optical trap force of PMMA beads. A powerful optical tweezers system based on a continuous wave Nd:YAG laser was used in order to estimate the trapping efficiency for several beads diameter.

Controllable, non-ablative photo-processing of collagen, elastic, muscle and cotton fibers was achieved by femtosecond Ti:Sa laser. Fibers were cut, bended and welded by the infrared laser and simultaneously imaged using second harmonic generation and two-photon auotoflourescence microscopy.

The specular transmittance spectrum of human corneas is studied using a confocal geometry set-up. The comparison of the obtained spectrum with the total transmittance spectrum permits the determination of the stromal scattering spectrum of pathological corneas. The dependence of the scattering cross section on wavelength dependence is analyzed.

The transmission properties of the human lens were studied in donor lenses from the age of 17 to 76 years. The transmission of white light was measured using a fiber coupled tungsten halogen lamp. The light transmitted by the lens was collected using an integrating sphere that was coupled to a spectrometer by an optical fiber. As expected, the transmission of blue and green light decreased in older lenses. The transmission of the near infrared part of the spectrum was above 90% even in old donor lenses.

Efficient cornea reshaping by laser irradiation for correcting refractive errors is still a major issue of interest and study. Although the excimer laser wavelength of 193 nm is generally recognized as successful in ablating corneal tissue for myopia correction, complications in excimer refractive surgery leads to alternative laser sources and methods for efficient cornea treatment. In this work, ablation experiments of human donor cornea flaps were conducted with the 4^th harmonic of an Nd:YAG laser, with different laser pulses. AFM analysis was performed for examination of the ablated cornea flap morphology and surface roughness.