Zoltán Zsolt Nagy

Initial clinical evaluation of an intraocular femtosecond laser in cataract surgery.

PURPOSE To evaluate femtosecond laser lens fragmentation and anterior capsulotomy in cataract surgery. METHODS Anterior capsulotomy and phacofragmentation procedures performed with an intraocular femtosecond laser (LenSx Lasers Inc) were initially evaluated in ex vivo porcine eyes. These procedures were then performed in an initial series of nine patients undergoing cataract surgery. In addition to standard intraoperative assessments (including capsulotomy diameter accuracy and reproducibility), optical coherence tomography was used to evaluate human procedures. RESULTS For an intended 5-mm capsulorrhexis in porcine eyes, average achieved diameters were 5.88+/-0.73 mm using a standard manual technique and 5.02+/-0.04 mm using the femtosecond laser. Scanning electron microscopy revealed equally smooth cut edges of the capsulotomy with the femtosecond laser and manual technique. Compared to control porcine eyes, femtosecond laser phacofragmentation resulted in a 43% reduction in phacoemulsification power and a 51% decrease in phacoemulsification time. In a small series of human clinical procedures, femtosecond laser capsulotomies and phacofragmentation demonstrated similarly high levels of accuracy and effectiveness, with no operative complications. CONCLUSIONS Initial results with an intraocular femtosecond laser demonstrate higher precision of capsulorrhexis and reduced phacoemulsification power in porcine and human eyes.

Femtosecond Laser Capsulotomy and Manual Continuous Curvilinear Capsulorrhexis Parameters and Their Effects on Intraocular Lens Centration

PURPOSE To measure and compare sizing and positioning parameters of femtosecond laser capsulotomy with manual continuous curvilinear capsulorrhexis (CCC). METHODS Femtosecond capsulotomies (Alcon-LenSx Lasers Inc) and CCC were carried out in 20 eyes of 20 patients, respectively. Intraocular lens (IOL) decentration, circularity, vertical and horizontal diameters of capsulotomies, and capsule overlap were measured with Adobe Photoshop (Adobe Systems Inc) 1 week, 1 month, and 1 year after surgery. Between-group differences of parameters and predictors of IOL decentration were determined with repeated measures analysis of variance, chi-square test, and logistic regression analyses. RESULTS Vertical diameter of CCC was statistically significantly higher in the first week and month. Significantly higher values of capsule overlap over 1 year and circularity in the first week showed more regular femtosecond capsulotomies. Horizontal IOL decentration was statistically significantly higher in the CCC group over 1 year. A significant difference was noted between the two groups in dichotomized horizontal decentration values at 0.4 mm with chi-square test after 1 week and 1 year (P=.035 and P=.016, respectively). In univariable general estimating equation models, type of capsulorrhexis (P<.01) and capsule overlap (P=.002) were significant predictors of horizontal decentration. Vertical diameter showed significant correlation to the overlap in the CCC group (1 week: r=-0.91; 1 month: r=-0.76, P<.01; 1 year: r=-0.62, P<.01), whereas no significant correlation was noted in the femtosecond group (P>.05). CONCLUSIONS More precise capsulotomy sizing and centering can be achieved with femtosecond laser. Properly sized, shaped, and centered femtosecond laser capsulotomies resulted in better overlap parameters that help maintain proper positioning of the IOL.

Comparison of Intraocular Lens Decentration Parameters After Femtosecond and Manual Capsulotomies

PURPOSE To evaluate a laser technique and manual technique to perform capsulorrhexis in cataract eyes. METHODS Anterior capsulotomy was performed with an intraocular femtosecond laser (LenSx Lasers Inc) in 54 eyes (FS group) and manual continuous curvilinear capsulorrhexis was performed in 57 eyes (CCC group). Circularity and area of capsulotomy and IOL decentration were measured using Photoshop CS4 Extended (Adobe Systems Inc) 1 week after surgery. Average keratometry, axial length, and preoperative anterior chamber depth were examined with the Lenstar LS 900 (Haag-Streit AG). RESULTS No statistically significant differences were noted between groups in axial length, preoperative refractive state, and in the area of capsulotomy. Circularity values were significantly better in the FS group (P=.032). We found incomplete overlap of capsulotomies in 28% of eyes in the CCC group and 11% in the FS group (P=.033). Significant correlations were noted between axial length and area of capsulotomy, and between average keratometry and area of the capsulotomy in the CCC group (R=0.278, P=.036; and R=-0.29, P=.033, respectively), but both did not correlate in the FS group (P>.05). In the CCC group, the pupillary area correlated significantly with the area of the capsulotomy (R=0.27, P=.039). Significant correlation was noted between IOL decentration and axial length in the CCC group (R=0.30, P=.026), but there was no correlation in the FS group (P>.05). CONCLUSIONS Femtosecond laser capsulorrhexis was more regularly shaped, showed better centration, and showed a better intraocular lens/capsule overlap than manual capsulorrhexis.

Central corneal volume and endothelial cell count following femtosecond laser-assisted refractive cataract surgery compared to conventional phacoemulsification

PURPOSE To compare the effect of conventional phacoemulsification and femtosecond laser-assisted cataract surgery on the cornea using Scheimpflug imaging and noncontact specular microscopy. METHODS In each group, 38 eyes (38 patients) underwent cataract surgery using either femtosecond laser-assisted (Alcon LenSx laser) (femtolaser group) or conventional phacoemulsification (phaco group). Central corneal thickness, 3-mm corneal volume, and Pentacam Nucleus Staging (PNS) were determined by a rotating Scheimpflug camera (Pentacam HR, Oculus Optikgeräte GmbH), and the volume stress index was calculated at 1 day and 1 month postoperatively. Endothelial cell count was measured by noncontact specular microscopy preoperatively, 1 day, 1 week, and 1 month postoperatively. RESULTS Central corneal thickness was significantly higher in the phaco group (607±91 μm) than in the femtolaser group (580±42 μm) on day 1, but did not differ significantly preoperatively and at 1 week and 1 month. Volume stress index at day 1 was significantly lower in the femtolaser group than in the phaco group (P<.05) but did not differ significantly at 1 month. Multivariate regression analysis showed that the type of surgery had a significant effect on central corneal thickness. CONCLUSIONS Femtosecond laser-assisted cataract surgery causes less corneal swelling in the early postoperative period and may cause less trauma to corneal endothelial cells than manual phacoemulsification.

Intraocular lens tilt and decentration measured by scheimpflug camera following manual or femtosecond laser-created continuous circular capsulotomy

PURPOSE To compare intraocular lens (IOL) decentration and tilt following a circular capsulotomy created with a femtosecond laser (laser CCC) to a manually performed continuous curvilinear capsulorrhexis (manual CCC). METHODS In a prospective, randomized study, a laser CCC (Alcon LenSx Inc) was performed in 20 eyes from 20 patients and a manual CCC was performed in 25 eyes from 25 patients. Intraocular lens decentration and tilt were measured using a Scheimpflug camera (Pentacam, Oculus Optikgeräte GmbH) 1 year after surgery. Uncorrected (UDVA) and corrected distance visual acuity (CDVA) and manifest refraction were also determined postoperatively. Between-group differences of IOL decentration and tilt as well as the correlation between IOL decentration and postoperative refractive changes and between IOL tilt and visual acuity were analyzed. RESULTS Horizontal and vertical tilt were significantly higher in the manual CCC group (P=.007 and P<.001, respectively). Lenses implanted after manual CCC showed greater horizontal and total decentration (P=.034 and P=.022, respectively). Significant differences were found in the homogeneity of dichotomized IOL vertical tilt and both horizontal and total decentration distribution (P=.008, P=.036, and P=.017, respectively). Total IOL decentration showed a significant correlation with changes in manifest refraction values between 1 month and 1 year after surgery (R=0.33, P=.032). A significant correlation was noted between IOL vertical tilt and CDVA (R(2)=0.17, β=-0.41, 95% confidence limit: -0.69 to -0.13, P=.005). CONCLUSIONS Continuous curvilinear capsulorrhexis created with a femtosecond laser resulted in a more stable refractive result and less IOL tilt and decentration than manual CCC.

Internal Aberrations and Optical Quality After Femtosecond Laser Anterior Capsulotomy in Cataract Surgery

PURPOSE To compare ocular and internal aberrations after femtosecond laser anterior capsulotomy and continuous curvilinear capsulorrhexis in cataract surgery. METHODS In this prospective study, anterior capsulotomy was performed during cataract surgery with an intraocular femtosecond (FS) laser (Alcon LenSx Inc) in 48 eyes. As a control group, continuous curvilinear capsulorrhexis (CCC) was performed in 51 eyes. Wavefront aberrometry, corneal topography, and objective visual quality were measured using the OPD-Scan (NIDEK Co Ltd). Vertical and horizontal tilt, coma, and visual quality metrics were evaluated separately to determine whether the source of aberrations was ocular or internal. Main outcome measures included postoperative residual refraction, uncorrected and corrected visual acuities, ocular and internal aberrations, Strehl ratio, and modulation transfer function (MTF). RESULTS No statistically significant differences were noted between the FS and CCC groups, respectively, in postoperative sphere (-0.60 ± 1.50 vs -0.50 ± 1.40 diopters [D]), postoperative cylinder (1.30 ± 1.01 vs 1.10 ± 1.10 D), uncorrected distance visual acuity (0.86 ± 0.15 vs 0.88 ± 0.08), or corrected distance visual acuity (0.97 ± 0.08 vs 0.97 ± 0.06). The FS group had significantly lower values of intraocular vertical tilt (-0.05 ± 0.36 vs 0.27 ± 0.57) and coma (-0.003 ± 0.11 vs 0.1 ± 0.15), and significantly higher Strehl ratios (0.02 ± 0.02 vs 0.01 ± 0.01) and MTF values at all measured cycles per degree, compared to the CCC group. CONCLUSIONS Capsulotomy performed with an intraocular FS laser induced significantly less internal aberrations measured by the NIDEK OPD-Scan aberrometer compared to eyes that underwent CCC, which may result in better optical quality after the procedure.

Comparison of IOL power calculation and refractive outcome after laser refractive cataract surgery with a femtosecond laser versus conventional phacoemulsification

PURPOSE To compare intraocular lens (IOL) power calculation and refractive outcome between patients who underwent laser refractive cataract surgery with a femtosecond laser and those with conventional cataract surgery. METHODS In this prospective study, 77 eyes from 77 patients underwent laser refractive cataract surgery (laser group; Alcon LenSx femtosecond laser), and conventional cataract surgery with phacoemulsification was performed in 57 eyes from 57 patients (conventional group). Biometry was done with optical low coherence reflectometry (Lenstar LS900, Haag-Streit AG), and IOL calculation was performed with third-generation IOL formulas (SRK/T, Hoffer Q, and Holladay). The refractive outcome was analyzed using the mean absolute error (MAE; difference between predicted and achieved postoperative spherical equivalent refraction), and multivariable regression analysis was performed to compare the two groups. RESULTS No significant differences were found between age, axial length, keratometry, and preoperative corrected visual acuity in the laser and conventional groups (P>.05; Mann-Whitney U test). At least 6 weeks after surgery, MAE was significantly lower in the laser group (0.38±0.28 diopters [D]) than in the conventional group (0.50±0.38 D) (P=.04). The difference was the greatest in short (axial length <22.0 mm, 0.43±0.41 vs 0.63±0.48) and long (axial length >26.0 mm, 0.33±0.24 vs 0.63±0.42) eyes. CONCLUSIONS Laser refractive cataract surgery with a femtosecond laser resulted in a significantly better predictability of IOL power calculation than conventional phacoemulsification surgery. This difference is possibly due to a more precise capsulorrhexis, resulting in a more stable IOL position.

Evaluation of keratometric, pachymetric, and elevation parameters of keratoconic corneas with pentacam

Purpose: The purpose of this study was to evaluate the alteration of keratometric, pachymetric, and elevation parameters of keratoconic and normal corneas with the Pentacam Scheimpflug camera. Methods: Pentacam measurements were performed on 41 eyes of 24 patients with keratoconus and 70 eyes of 41 normal subjects. In each eye, keratometric values, central and minimal pachymetry, and anterior and posterior elevation were evaluated. Receiver operating characteristic curves were used to compare the sensitivity and specificity of the different parameters. Predictors of keratometric, pachymetric, and elevation data were evaluated by logistic regression analysis. Confirmatory factor analysis was performed in the keratoconus group to quantify the validity of critical parameters for keratoconus. Results: All parameters were significantly different in the keratoconus group compared with the normal control group. Receiver operating characteristic curve analyses showed the best predictive accuracy for posterior and anterior elevation (area under the curve, 0.97 and 0.96) followed by minimal and central pachymetry (0.89 and 0.88). The optimal cutoff point for posterior elevation was 15.5 μm for the discrimination of keratoconus corneas from normal. Logistic regression analysis showed best fit to the data for the model completed with the height data of the Pentacam. Confirmatory factor analysis explained a 3-factor model satisfactorily showing minimal pachymetry (-0.99), anterior elevation (0.98), and keratometry (0.95) as the most representative clinical variables of the disease. Conclusion: Posterior and anterior elevation, pachymetric, and keratometric parameters measured by the Pentacam camera can effectively discriminate keratoconus from normal corneas serving as a useful diagnostic tool for disease staging.

Effect of Femtosecond Laser Cataract Surgery on the Macula

PURPOSE To compare the effect of conventional and femtosecond laser-assisted (Alcon LenSx Inc) phacoemulsification on the macula using optical coherence tomography (OCT). METHODS Twenty eyes of 20 patients underwent uneventful cataract surgery in both study groups: femtosecond laser-assisted (laser group) and conventional phacoemulsification (control group). Macular thickness and volume were evaluated by OCT preoperatively and 1 week and 1 month postoperatively. Primary outcomes were OCT retinal thickness in 3 macular areas and total macular volume at 1 week and 1 month postoperative. Secondary outcomes were changes in retinal thickness at 1 week and 1 month postoperatively, with respect to preoperative retinal thickness values and effective phacoemulsification time. RESULTS Multivariable modeling of the effect of surgery on postoperative macular thickness showed significantly lower macular thickness in the inner retinal ring in the laser group after adjusting for age and preoperative thickness across the time course (P=.002). In the control group, the inner macular ring was significantly thicker at 1 week (mean: 21.68 μm; 95% confidence limit [CL]: 11.93-31.44 μm, P<.001). After 1 month, this difference decreased to a mean of 17.56 μm (95% CL: -3.21-38.32 μm, P=.09) and became marginally significant. CONCLUSIONS Results of this study suggest that femtosecond laser-assisted cataract extraction does not differ in postoperative macular thickness as compared with standard ultrasound phacoemulsification.

Complications of femtosecond laser-assisted cataract surgery.

Purpose To analyze complications of femtosecond lasers used for cataract surgery. Setting Department of Ophthalmology Semmelweis University, Budapest, Hungary. Design Retrospective analysis. Methods Intraoperative complications of the first 100 femtosecond laser–assisted (Alcon‐Lensx, Inc.) cataract surgeries were collected. Possible complications of femtosecond capsulotomies and their management were also assessed. Results The complications were as follows: suction break (2%), conjunctival redness or hemorrhage (34%), capsule tags and bridges (20%), anterior tear (4%), miosis (32%), and endothelial damage due to cut within the endothelial layer (3%). There were no cases of capsule blockage or posterior capsule tear. During the learning curve, there was no complication that would require vitrectomy. All complications occurred during the first 100 cases. Conclusions Femtosecond laser cataract surgery had a learning curve during the first 100 cases. With cautious surgical technique, the complications can be avoided. The femtosecond laser–assisted method was efficient and safe for cataract surgery. Financial Disclosure Drs. Nagy, T. Juhász, and Slade are consultants to Alcon‐Lensx, Inc. No other author has a financial or proprietary interest in any material or method mentioned.