Methods: Absorption coefficients were obtained for each of the component species found in balanced salt solution. This was achieved by measuring laser pulse transmission through solutions of varying concentration. The experiments were repeated using the 193-nm excimer and 213-nm solid-state laser wavelengths. Results for each species were then used to obtain an overall absorption coefficient and penetration depth for balanced salt solution and 0.9% sodium chloride solution. Results: Absorption coefficients in balanced salt solution for the 193- and 213-nm wavelengths were found to be 140 and 6.9 cm ˛1 , respectively. In 0.9% sodium chloride solution, the absorption coefficient was 81 cm ˛1 at 193 nm and 0.05 cm ˛1 at 213 nm. At 193 nm, absorp

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Absorption of 193- and 213-nm laser wavelengths in sodium chloride solution and balanced salt solution.

Apparatus for performing ultraviolet laser ablation of a surface, eg. an eye surface, including a laser delivery system ( 7 ) having a laser source ( 1 ) for generating a laser beam ( 2 ) and optics for applying the laser beam to the surface to be ablated, means ( 20, 20 ′) for providing a compatible liquid ( 32 ) in contact with the surface ( 4 a ) to be ablated, in a position whereby said laser beam ( 2 ) is applied to said surface through the liquid, wherein the laser beam is of a wavelength that substantially is not absorbed by the liquid.

Apparatus and procedure for ultraviolet laser ablation

PURPOSE: To study the long-term results of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) in low to moderate myopic corrections using the Pulzar Z1 system (CustomVis), a 213 nm wavelength solid-state laser. SETTING: University refractive surgery center. METHODS: This prospective noncomparative case series comprised 20 patients (40 eyes) who had refractive surgery using the Pulzar Z1 laser system. Manifest refraction, uncorrected visual acuity, best spectacle-corrected visual acuity (BSCVA), safety, predictability, stability, and confocal microscopy images were evaluated. RESULTS: Ten patients (20 eyes) had PRK and 10 patients (20 eyes) had LASIK. The mean followup was 13.9 months G 1.1 (SD) (range 12 to 17 months) and 14.6 G 1.2 months (range 12 to 18 months) in thePRKgroup andLASIKgroup, respectively. Noeyelost aline ofSnellen BSCVA during the follow-up period; 2 eyes (10%) gained 2 Snellen lines. There was a statistically significant decrease in sphericalequivalent manifest refraction postoperatively inbothgroups (P .05). At the last followup, 95% of all eyes were within G1.00 diopter of emmetropia. No late postoperative complications were observed. CONCLUSION: Refractive surgery using the Pulzar Z1 213 nm wavelength solid-state laser was a safe, effective procedure in the treatment of low to moderate myopia. J Cataract Refract Surg 2007; 33:971–977 Q 2007 ASCRS and ESCRS

One-year results of photorefractive keratectomy and laser in situ keratomileusis for myopia using a 213 nm wavelength solid-state laser.

PURPOSE: To investigate the effect of temporal and spatial distributions of laser spots (scan sequences) on the corneal surface quality after ablation and the maximum ablation of a given refractive correction after photoablation with a high-repetition-rate scanning-spot laser. SETTING: IROC AG, Zurich, Switzerland, and WaveLight AG, Erlangen, Germany. METHODS: Bovine corneas and poly(methyl methacrylate) (PMMA) plates were photoablated using a 1050 Hz excimer laser prototype for corneal laser surgery. Four temporal and spatial spot distributions (scan sequences) with different temporal overlapping factors were created for 3 myopic, 3 hyperopic, and 3 phototherapeutic keratectomy ablation profiles. Surface quality and maximum ablation depth were measured using a surface profiling system. RESULTS: The surface quality factor increased (rough surfaces) as the amount of temporal overlapping in the scan sequence and the amount of correction increased. The rise in surface quality factor was less for bovine corneas than for PMMA. The scan sequence might cause systematic substructures at the surface of the ablated material depending on the overlapping factor. The maximum ablation varied within the scan sequence. CONCLUSIONS: The temporal and spatial distribution of the laser spots (scan sequence) during a corneal laser procedure affected the surface quality and maximum ablation depth of the ablation profile. Corneal laser surgery could theoretically benefit from smaller spot sizes and higher repetition rates. The temporal and spatial spot distributions are relevant to achieving these aims.

Influence of spatial and temporal spot distribution on the ocular surface quality and maximum ablation depth after photoablation with a 1050 Hz excimer laser system

Purpose To investigate the efficiency and ablation profiles of a newly developed, all-solid-state laser platform. Setting Experimental investigations performed at Katana Technologies GmbH, Kleinmachnow, Germany, and clinical study, at the Ophthalmology Clinic, University of Messina, Messina, Italy. Methods Experimental studies were performed on poly(methyl methacrylate) (PMMA) and in porcine eyes using an all-solid-state, Q-switched, frequency-shifted laser (LaserSoft, Katana Technologies GmbH) with a Gaussian spot with a diameter of 0.2 mm in the target plane, a peak fluence of 350 mJ/cm2, and a repetition rate of 1 kHz. The ablation profiles were determined using a profile meter (MicroProf, Fries Research and Technology GmbH), corneal topography was analyzed with a TMS 2N (Tomey Inc.), and corneal thickness was measured with an ultrasound pachymeter (DGH Technology). In the clinical study, 9 human eyes were treated with photorefractive keratectomy. The mean outcome measures were uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), corneal topography, and corneal transparency. The follow-up was 1 month for all eyes and 3 months for 4 eyes. Safety, efficacy, and predictability were evaluated. Results Smooth profiles were found in the PMMA and the porcine eyes. The topographic maps showed central steepening after the hyperopic ablation and slight central flattening of the surface after the myopic treatment. No eye lost lines of BSCVA; the UCVA improved in all eyes. All eyes were within ±1.00 diopter (D) of emmetropia, and 89% were within ±0.50 D. Conclusion The efficacy of the ablation was good, with the profile meter results confirmed by the topographic measurements.

Experimental and clinical investigation of efficiency and ablation profiles of new solid-state deep-ultraviolet laser for vision correction.

PURPOSE. To determine the threshold and efficiency of corneal ablation for various values of laser fluence at the ultraviolet wavelength of 213 nm. METHODS. A commercial Q-switched Nd:YAG laser was used to produce the fifth harmonic wavelength of 213 nm. Ablation trials were carried out on porcine corneas. Slit ablations of dimensions 0.5 × 2.5 mm were performed using seven values of laser fluence to obtain the most efficient fluence for ablation. The morphology of each ablation was obtained using a computer-automated confocal profiling system. These profiles were then analyzed to determine the ablation depth for the range of fluence values used. RESULTS. A fluence in the region of 200 mJ/cm 2 was found to be the most efficient for ablation. The efficiency in this region was approximately 0.35 mm 3 /J, and the ablation rate was found to be 0.6 μm/pulse. The ablation threshold was found to occur at a fluence of 50 mJ/cm 2 . In the region of highest efficiency, the peak varied slightly in the fluence range between 150 and 250 mJ/cm 2 . CONCLUSIONS. This study confirms that the corneal ablation properties at 213 nm are comparable with those at the 193-nm excimer laser wavelength. Increased pulse energy was obtained for the fifth harmonic of Nd:YAG lasers at 213 nm through the use of new nonlinear optical crystals to perform the frequency conversion. A solid state laser is feasible to replace the excimer gas laser for performing refractive surgery procedures. For the first time, the increased energy at 213 nm allows large-beam ablations to be performed at this wavelength.

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Investigation of corneal ablation efficiency using ultraviolet 213-nm solid state laser pulses.