Shielding effect of the smoke plume by the ablation of excimer lasers.

BACKGROUND: Shielding and scattering effect of the smoke plume column ejected from the laser ablated material is a well-known phenomenon. Debris evacuation system of the excimer laser equipment removes these particles, but insufficient air flow can result in undesired refractive outcomes of the treatment. The aim of this study was to reveal the effect of the air flow speed on the actual ablation depth. METHODS: SCWIND AMARIS 500E flying spot excimer laser was tested in this study. A 150 µm phototherapeutic keratectomy (PTK) profile with 8 mm diameter was applied to the surface of polymethyl methacrylate (PMMA) plates. The velocity of the air flow was changed with adjustable air aspiration system. Ablation depth was measured with highly-precise contact micrometer. RESULTS: The prediction model was statistically significant, F(1,8) = 552.85, p < 0.001, and accounted for approximately 98.7% of variance of ablation (R2 = 0.987, R2adj = 0.986). Lower air flow speed resulted in a weaker ablation capability of the excimer laser. CONCLUSION: Air flow generated by the aspiration equipment is a key factor for the predictable outcomes of refractive treatment. Therefore, manufacturer inbuilt debris removal system should be regularly checked and maintained to ensure proper clinical and predictable refractive results.

[Relationship between corneal surface temperature and air flow conditions during refractive laser eye surgery using three different excimer lasers]. / A szaruhártya felszíni homérséklete és légáramlási viszonyainak alakulása refraktív célú lézeres beavatkozás közben három különbözo típusú és ismétlési frekvenciájú excimer lézerberendezésnél.

INTRODUCTION: Thermal conditions during photorefractive keratectomy might be an important issue related to the corneal wound healing and long-term outcomes. AIM: Authors tried to find out the importance of temperature conditions during the treatment. METHOD: One eye of 90 patients has been included into the study. Photorefractive keratoctomy was applied with Carl Zeiss MEL 70, MEL 80 and Wavelight Allegretto excimer lasers. EBRO TLC 730 infrared thermometer was used for the measurement of surface temperature of the cornea before epithelial removal, as well as before and after the treatment. Average age of the patients was 25.5 ± 3 yr. Average myopic correction was -3.2 ± 0.8 Dpt. RESULTS: Statistically significant difference was found in temperature change between MEL 80 and the other two types of excimer laser devices. CONCLUSIONS: Different air flow conditions of the smoke removal system might have an influence on changes of the corneal temperature during treatment, but the refractive results were not influenced by this issue. Orv. Hetil., 2016, 157(43), 1717-1721.

Comparison of the current and a new RTVue OCT software version for detection of ganglion cell complex changes due to cataract surgery.

The purpose was to compare the current (6.3) and a novel software version (6.12) of the RTVue-100 optical coherence tomograph (RTVue OCT) for ganglion cell complex (GCC) and retinal nerve fibre layer thickness (RNFLT) changes after phacoemulsification in healthy cataract eyes, and to investigate whether version 6.12, in which image segmentation is improved, provides benefits over version 6.3 for RNFLT and GCC imaging via mild cataract. One eye of 22 consecutive healthy cataract patients were imaged before and 1 month after uncomplicated cataract surgery using RTVue-100 OCT software version 6.3. The images were analysed with both software versions. Signal strength index increased significantly after surgery for both RNFLT and the GCC measurements (p ≤ 0.0015). No difference was seen for any RNFLT parameter between the software versions and time points (p ≥ 0.0140). The GCC values did not differ between the versions either before or after surgery (p ≥ 0.4471), but all increased significantly after surgery with software version 6.12 (p < 0.0001). Neither focal loss volume (FLV) nor global loss volume (GLV) differed between the software versions before and after surgery, respectively, but GLV decreased (improved) significantly after surgery (p = 0.010 and <0.001 for versions 6.3 and 6.12, respectively). Cataract surgery induced similar changes with both software versions, but version 6.12 identified the increase of GCC thickness and the decrease of GLV better than the current version. Although no significant difference between software versions was seen before surgery, our results suggest that version 6.12 may be more precise in measuring GCC parameters than the currently available version.

[Results of femtosecond laser-assisted cataract surgery using the new 2.16 software and the SoftFit® Patient Interface]. / A femtoszekundumlézer-asszisztált szürkehályog-mutét eredményei az új 2.16-os szoftverrel és a módosított SoftFit® páciensi felszínnel.

INTRODUCTION: Femtosecond laser-assisted cataract surgery improved the results of cataract surgeries. AIM: Outcome analysis of femtosecond laser-assisted cataract surgery using the novel 2.16 software and the SoftFit(®) Patient Interface. METHOD: The novel software and the newly developed Patient Interface were used in 100 eyes of 100 patients. RESULTS: Length of femtosecond laser pretreatment decreased to 45-60 seconds. The smaller size of the new patient interface resulted in easier docking even on pediatric eyes. Suction force used for docking decreased from 40-50 mmHg to 16-20 mmHg. Incidence rate of subconjunctival suffusion decreased from 40% to 15-20% and its clinical severity was reduced, too. No corneal microfolds evolved, thus the incidence rate of the free-floating capsulotomies increased from 30% to 97%. The total energy of femtosecond laser pretreatment was decreased by almost 50%. Corneal wounds had the desired structure, and they were easy to open and closed precisely. CONCLUSIONS: The SoftFit(®) patient interface and the novel software widened the possible uses of the femtosecond laser-assisted cataract surgery, e.g. in pediatric ophthalmology. Innovations improved the safety and the predictability of the method.

Analysis of planned and postoperatively measured flap thickness after LASIK using the LenSx multifunctional femtosecond laser system.

PURPOSE: To evaluate LASIK corneal flaps using a multifunctional femtosecond laser suitable for cataract and corneal surgery (LenSx; Alcon Laboratories, Inc., Aliso Viejo, CA) and to compare the planned and postoperatively measured flap thickness using an anterior segment optical coherence tomography device (AS-OCT). METHODS: Twenty patients (38 eyes) diagnosed as having myopia and myopic astigmatism were enrolled. LASlK was performed using the LenSx femtosecond laser for intracorneal flaps and the Wavelight Allegretto 400 excimer laser (Alcon Laboratories, Inc.) for intra- stromal photoablation. Desired flap thickness and diameter were 140.0 + 0.0 pm and 8.5 + 0.0 mm, respectively, whereas mean ablation depth and diameter of the excimer laser treatment were 67.9 ± 24.18 pm and 6.5 ± 0.08 mm, respectively. Entered data of the LenSx femtosecond laser were used to determine desired flap thickness, whereas AS-OCT (RTVue; Optovue, Inc., Fremont, CA) was used to measure flap thickness postoperatively. The Wilcoxon signed-rank test, dependent paired t test, and Friedman test were used for comparison of dependent and repeated measures. RESULTS: There was no statistically significant difference in the planned and postoperatively measured flap thickness (140.0 ± 0.0 vs 140.28 _ 8.0 pm; P = .4067). Interfaces of the flaps had even surfaces according to the images and calculations on the AS-OCT device (P = .058). CONCLUSIONS: Application of this multifunctional femtosecond laser performing LASIK proved to be a safe and effective method regarding predictability of flap thickness.

Intraocular femtosecond laser use in traumatic cataract.

PURPOSE: To report the use of femtosecond laser cataract surgery in a traumatic case. METHODS: A 38-year-old man had a penetrating eye injury while working with wire. The corneal laceration was sutured first. In the postoperative period, cortical cataract appeared in the crystalline lens; therefore, in the second session, cataract surgery was performed using a femtosecond laser system (Alcon-LenSx Lasers Inc.). RESULTS: Corneal incisions, an intact 4.5 mm capsulorhexis, and nucleus liquefaction were performed with the femtosecond laser. Corrected distance visual acuity was 0.9 1 month after surgery. CONCLUSIONS: Femtosecond laser is an effective method in traumatic cataract cases after penetrating eye injury. Corneal incisions, capsulorhexis, and nucleus liquefaction can be performed precisely and safety.

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.

Femtosecond laser cataract incision morphology and corneal higher-order aberration analysis.

PURPOSE: Analysis of the femtosecond laser refractive lens surgery corneal incision configuration and corneal higher-order aberration (HOA) effect from the first postoperative day. METHODS: High-resolution anterior segment optical coherence tomography was used to assess 20 eyes undergoing femtosecond laser refractive lens surgery with 2.2-mm minimal incision. The primary incision (tri-planar) actual length, cord length, surface angle, surface irregularity, and regional pachymetry values and the secondary incision (uni-planar) length, angle, surface irregularity, and pachymetry values were analyzed. Hartmann-Shack aberrometer was used to assess corneal HOAs to correlate the effect. Assessment was done preoperatively and 1 month postoperatively. RESULTS: The actual length, cord length, and surface angle means for the primary incision in the first postoperative day and month were 1.50 ± 0.1 and 1.47 ± 0.2 mm (P = .5), 1.41 ± 0.1 and 1.42 ± 0.2 mm (P = .8), and 27° ± 4° and 23° ± 5° (P = .07), respectively. The length and surface angle for the secondary incision in the first postoperative day and month were 1.17 ± 0.01 and 1.04 ± 0.1 mm (P = .05) and 52° ± 3° and 42° ± 5° (P = .007). The regional pachymetry values for the primary and secondary incisions were significantly increased in the first postoperative day and then significantly decreased after 1 month. All irregularities occurred in the posterior surface (endothelium): 2 cases of posterior gap (first day) and 1 case of posterior retraction (first month). The HOAs had not significantly changed preoperatively and after 1 month. CONCLUSIONS: The femtosecond laser refractive lens surgery incision is stable and does not significantly change the HOA.

Femtosecond laser-assisted cataract surgery in management of phacomorphic glaucoma.

PURPOSE: To report the use of femtosecond laser-assisted cataract surgery in management of phacomorphic glaucoma. METHODS: An 89-year-old patient developed acute phacomorphic glaucoma in her right eye with elevated intraocular pressure (62 mm Hg), shallow anterior chamber, and mature cataract. After conservative antiglaucoma therapy and Nd:YAG iridotomy, femtosecond laser-assisted cataract surgery was performed. A Malyugin ring was implanted for mechanical pupil dilatation and a 4.8-mm capsulorrhexis and lens fragmentation was performed using a femtosecond laser system (Alcon LenSx Inc., Aliso Viejo, CA) followed by in-the-bag intraocular lens implantation. RESULTS: Intact 4.8-mm capsulorrhexis and successful lens fragmentation could be performed using femtosecond laser. After cataract surgery, the patient's visual acuity increased from hand motions to 0.4 (Snellen 4/10) and the intraocular pressure returned to normal range without antiglaucoma drop therapy. CONCLUSIONS: The results indicate that femtosecond laser can be successfully used in certain cases of phacomorphic glaucoma, even if mechanical pupil dilatation is needed.

Anterior segment OCT imaging after femtosecond laser cataract surgery.

PURPOSE: To report the anterior segment imaging characteristics after femtosecond laser assisted cataract surgery. METHODS: Cataract surgery was performed with the LenSx femtosecond laser (Alcon-LenSx Inc., Aliso Viejo, CA) in 40 eyes of 40 patients. The laser was programmed to perform a 4.5-mm capsulorhexis, a cross-pattern fragmentation of the nucleus, a 2.8-mm main incision, and a 1.0-mm side-port incision. The anterior segment was then analyzed using the Visante OCT anterior segment program (Zeiss-Meditec AG, Jena, Germany). RESULTS: The preoperatively set treatment parameters correlated well with the achieved results. For the capsulorhexis, the femtosecond laser cut was programmed to start 350 µm behind the anterior lens capsule and OCT measured 377 ± 55.3 µm. Nucleus fragmentation was programmed to start 750 µm in front of the posterior capsule and end 550 µm behind the anterior capsule, and OCT measured 794 ± 111 and 568 ± 147 µm, respectively. The diameter of the capsulorhexis measured by OCT was 4.54 ± 0.2 mm, compared to the 4.5 mm programmed. CONCLUSIONS: Anterior segment OCT imaging was able to detect the tissue changes within the lens after femtosecond laser capsulorhexis and nucleus fragmentation. The measured values correlated well with the planned treatment parameters.

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.

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 femtosecond laser use in traumatic cataracts following penetrating and blunt trauma.

PURPOSE: To investigate the use of femtosecond laser cataract surgery in traumatic cataracts of different origin. METHODS: The first case developed acute traumatic cataract due to penetrating injury of the cornea and the anterior lens capsule; the second developed traumatic cataract 11 years after a penetrating corneal injury; and the third developed a "white" cataract 12 months after blunt ocular trauma. In all cases, 4.5-mm capsulorrhexis and corneal incisions were performed using a femtosecond laser system (Alcon LenSx Inc), and nucleus liquefaction with the laser was performed additionally in the second case. RESULTS: In all patients, a capsulorrhexis could be created with the femtosecond laser. Preexisting radial tears were present in the first case, but the remaining anterior capsule could be cut with the laser. The second and third cases showed an intact 4.5-mm capsulorrhexis. Corneal incisions were stable in all cases, and nucleus liquefaction was possible in the second case (grade 1-2 nuclear density). CONCLUSIONS: Results indicate that a femtosecond laser can be used successfully in certain instances of traumatic cataract after penetrating eye injury, even if an anterior capsule laceration is present, and also after blunt trauma resulting in "white" cataracts.

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.

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.

The variant N363S of glucocorticoid receptor in steroid-induced ocular hypertension in Hungarian patients treated with photorefractive keratectomy.

PURPOSE: Variation in sensitivity to glucocorticoids observed in healthy population is influenced by genetic polymorphisms of the glucocorticoid receptor gene (NR3C1). N363S, ER22/23EK, and Bcl I have been previously described as glucocorticoid-sensitivity modulating polymorphisms. We investigated whether these variants may contribute to steroid-induced ocular hypertension and if they play a role as protective or risk factors during exogenous glucocorticoid administration. METHODS: We examined 102 patients who underwent photorefractive keratectomy and received topical steroids (either fluorometholone 0.1% or prednisolone acetate 0.5% alone or combined) as part of postoperative therapy. The choice of steroid depended on course of wound healing and regression. Variations in intraocular pressure (IOP) levels in response to steroid therapy were observed. To genotype DNA, allele-specific PCR amplification was applied for the N363S polymorphism, and PCR-based restriction fragment length polymorphism analysis was performed to examine the Bcl I and the ER22/23EK polymorphisms. We separately analyzed data from three groups of patients: those who received fluorometholone only; those who were initially given fluorometholone then later switched to prednisolone acetate; and those who received prednisolone acetate only. Covariance analysis with forward stepwise variable selection was carried out. RESULTS: In cases where prednisolone acetate was administered, we found a significant correlation between N363S heterozygosity and steroid-induced ocular hypertension. ER22/23EK and Bcl I polymorphisms do not have a major influence on the risk of developing steroid-induced ocular hypertension. CONCLUSIONS: Genotyping of high risk steroid responders may allow an individual therapy to avoid steroid-induced ocular hypertension. The N363S polymorphism may have a clinical significance in the future.