Illés Kovács

Mitochondrial alterations of retinal pigment epithelium in age-related macular degeneration

Mitochondrial dysfunctions have been implicated in the pathophysiology of several age-related diseases including age-related macular degeneration (AMD), a progressive neurodegenerative disease affecting primarily the retinal pigment epithelium (RPE). The aims of our electron microscopic and morphometric studies were to reveal qualitative and quantitative alterations of mitochondria in human RPE from AMD and from age- and sex-matched controls. With increasing age a significant decrease in number and area of mitochondria, as well as loss of cristae and matrix density were found in both AMD and control specimens. These decreases were significantly greater in AMD than in normal aging. Alterations of mitochondria were accompanied by proliferation of peroxisomes and lipofuscin granules in both AMD and control specimens, although the difference between groups was significant only for peroxisomes. Unexpectedly, morphometric data showed that the RPE alterations seen in AMD may also develop in normal aging, 10-15 years after appearing in AMD patients. These findings suggest that (i) the severity of mitochondrial and peroxisomal alterations are different between AMD and normal aging, and (ii) the timing of damage to RPE may be critical for the development of AMD. We conclude that besides the well-documented age-related changes in mitochondrial DNA, alterations of mitochondrial membranes may also play a role in the pathogenesis of AMD. These membranes could be a new target for treatment of AMD and other age-related diseases.

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.

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.

Macular morphology assessed by optical coherence tomography image segmentation after femtosecond laser–assisted and standard cataract surgery

PURPOSE: To evaluate and compare thickness changes in the retinal layers in the macula with optical coherence tomography (OCT) segmentation software after femtosecond laser–assisted phacoemulsification (study group) and conventional phacoemulsification (control group). SETTING: Department of Ophthalmology, Semmelweis University, Budapest, Hungary. DESIGN: Case‐control study. METHODS: Total retinal thickness of the macula was evaluated using Stratus OCT 4 to 8 weeks postoperatively. The OCT images were segmented using OCT retinal image analysis software. Regional thickness data in the central area, inner rings, and outer rings were obtained and absolute and relative thicknesses of the individual retinal layers in the 2 study groups compared. Relative thickness was calculated as the ratio of the retinal layer to the total retinal thickness. RESULTS: All surgeries were uneventful. Statistically significant differences were found in absolute outer nuclear layer thickness and relative outer nuclear layer thickness in the inner and outer macular rings between the 2 groups. After adjusting for effective phaco time in multivariate modeling, type of surgery showed a significantly lower relative outer nuclear layer ratio in the inner retinal ring (0.26 with 95% confidence interval [CI], 0.25‐0.27 versus 0.28 with 95% CI, 0.27‐0.29; P=.03) and in the outer retinal ring (0.27 with 95% CI, 0.25‐0.28 versus 0.29 with 95% CI, 0.28‐0.31; P=.02) in the study group. CONCLUSION: After cataract surgery, macular edema was detectable mainly in the outer nuclear layer in both groups but was significantly less using the femtosecond laser platform. Financial Disclosure: Dr. Nagy is a consultant to Alcon‐LenSx Lasers, Inc. The University of Miami and Dr. Cabrera DeBuc hold a pending patent used in the study (U.S. patent 61/139,082) and have the potential for financial benefit from its future commercialization. Drs. Ecsedy, Kovács, Takács, Tátrai, and Somfai have no financial or proprietary interest in any material or method mentioned.