Kathleen S. Kunert

LASIK for Myopia Using the Zeiss VisuMax Femtosecond Laser and MEL 80 Excimer Laser

PURPOSE To assess the efficacy, safety, and predictability of the VisuMax femtosecond laser (Carl Zeiss Meditec). METHODS In a prospective, multicenter clinical trial, 32 eyes of 17 patients underwent LASIK and flap creation with the VisuMax femtosecond laser and ablation with the MEL 80 excimer laser (Carl Zeiss Meditec). Mean patient age was 35 years (range: 23 to 52 years). Mean preoperative spherical equivalent refraction was -4.04 +/- 1.39 diopters (D) (range: -1.50 to -7.25 D), and the planned flap thickness was 110, 120, 140, and 150 microm. RESULTS At the 3-month postoperative examination, all eyes had best spectacle-corrected visual acuity of 20/25 and uncorrected visual acuity (UCVA) of 20/40; 91% of eyes reached UCVA of 20/20 or better. Ninety-four percent of eyes were within +/- 0.50 D of the planned correction. Complications were limited to one case of suction loss, and no other adverse events were noted at 3 months. The flaps were planar and the mean achieved central flap thickness was 118 +/-9.2 microm for an attempted thickness of 120 microm. CONCLUSIONS The investigators achieved LASIK outcomes exceeding the US Food and Drug Administration guidelines for refractive procedures in this series of myopic eyes using the VisuMax femtosecond laser and MEL 80 excimer laser. The curved contact lens of the applanation glass combined with low suction permitted continuous fixation during treatment.

Surface quality of human corneal lenticules after femtosecond laser surgery for myopia comparing different laser parameters.

BackgroundTo determine the surface characteristics of human corneal lenticules after femtosecond laser surgery for myopia.MethodsThe Carl Zeiss Meditec AG VisuMax® femtosecond laser system was used for refractive correction called Femtosecond Lenticule Extraction on 24 myopic eyes. The surface regularity on the refractive corneal lenticules recovered was evaluated by assessing scanning electron microscopy images using an established scoring system. Three different energy levels 150, 180, and 195 nJ were compared (n = 8 in each group).ResultsSurface irregularities were caused by tissue bridges, cavitation bubbles, or scratches. The surface regularity index (R2 = 0.74) decreased as pulse energy increased. The average surface regularity score obtained was 7.5 for 150 nJ, 7.25 for 180 nJ, and 6.25 for 195 nJ.ConclusionsThe human corneal lenticules created with the VisuMax® femtosecond laser system are of predictable, good-quality surface. This study shows the influence of pulse energy on surface regularity in human eyes. Further studies should focus on optimization of laser parameters as well as surgical technique to improve the regularity of the corneal stromal bed and so make the advantages of the femtosecond laser technology over conventional techniques clearer in the future.

Five-year results of Small Incision Lenticule Extraction (ReLEx SMILE)

Background To evaluate the 5-year results of Refractive Lenticule Extraction (ReLEx) as Small Incision Lenticule Extraction (SMILE) technique for treatment of myopia and myopic astigmatism. Methods In 2008/2009, the worldwide first 91 eyes were treated using a novel surgical technique (SMILE), where a refractive lenticule of intrastromal corneal tissue is removed though a small incision completely eliminating flap-cutting. 56 out of 91 eyes of the original treatment group volunteered for re-examination 5 years after surgery. Uncorrected distance visual acuity and corrected distance visual acuity after 5 years, objective and manifest refractions as well as evaluation of the interface and corneal surface by slit-lamp examination were documented. Late side effects like corneal scars, corneal ectasia, persistent dry eye symptoms or cataract were documented. Results 5 years postoperatively, no significant change to the 6-month data was found. Spherical equivalent was −0.375 D and therefore close to target refraction (emmetropia). 32 of the 56 eyes had gained 1–2 Snellen lines. There was no loss of 2 or more lines over the 5-year period. Regression in the long term was 0.48 D. Conclusions This first long-term study demonstrates SMILE to be an effective, stable and safe procedure for treatment of myopia and myopic astigmatism. Clinical trial number DE/CA93/KP/07/001. Post-results.

Femtosecond Lenticule Extraction (FLEx) - Results after 12 Months in Myopic Astigmatism

BACKGROUND This clinical trial is focussed on the 12-month results of a new method for refractive correction, femtosecond lenticule extraction (FLEx). PATIENTS AND METHODS In a prospective 6-month study 108 eyes were treated in Erfurt and Marburg. Both a flap and a lenticule of intrastromal corneal tissue were simultaneously cut utilising the Carl Zeiss Meditec AG (Jena, Germany) VisuMax femtosecond laser system. Thereafter, the lenticule was manually removed and the flap repositioned. 31 patients all treated in Erfurt volunteered for a 12-month follow-up. UCVA and BSCVA after 12 months, objective and manifest refraction as well as slit-lamp examination and late side effects were documented. RESULTS 62 eyes of 31 patients were examined in this study. The spherical equivalent before surgery was -4.81 (± 1.16) D; after 12 months -0.15 (± 0.46) D were manifest. No significant change was observed after the 6 months control. Starting with UCVA of 0.12 (± 0.09) before surgery UCVA was 1.10 (± 0.26) after 12 months. In one patient corneal ectasia was diagnosed. All other patients did not have any late side effects. CONCLUSION The stability of the correction of myopic astigmatism with the FLEx procedure is very good. The fact that one patient presented with a corneal ectasia demonstrates that one general problem of refractive corneal surgery persists with this new fs technology.

Repeatability and agreement in optical biometry of a new swept-source optical coherence tomography–based biometer versus partial coherence interferometry and optical low-coherence reflectometry

Purpose To estimate the repeatability of biometric parameters obtained with a new swept‐source biometer and to compare the agreement with that of partial coherence interferometry (PCI) and optical low‐coherence reflectometry (OLCR). Setting Department of Ophthalmology, Helios Hospital Erfurt, Erfurt, Julius‐Maximilians University, Würzburg, and Philipps University, Marburg, Germany. Design Prospective comparative multicenter clinical study. Methods Biometry was taken with the use of 3 different biometers: the IOLMaster 700 swept‐source biometer, the PCI‐based IOLMaster 500, and the OCLR‐based Lenstar LS 900. Axial length (AL), anterior chamber depth (ACD), and spherical equivalent (SE) were compared between swept‐source and PCI biometry and central corneal thickness (CCT) and lens thickness (LT) between swept‐source and OLCR biometry. The repeatability of swept‐source biometry was evaluated on the basis of 3 measurements captured for each patient. Results One hundred twenty cataract eyes were included in the study. The mean difference between swept‐source and PCI biometry for AL, ACD, and SE measurements was 4 &mgr;m ± 25 (SD), 17 ± 122 &mgr;m, and −0.001 ± 0.19 diopter (D), respectively. The mean difference between swept‐source and OLCR biometry for LT and CCT measurements was 21 ± 122 &mgr;m and 0.15 ± 4.51 &mgr;m, respectively. Differences between swept‐source biometry and the other devices distributed around zero without statistical significance. The standard deviation of repeatability for AL, ACD, LT, CCT, and SE was 8.8 &mgr;m, 9.8 &mgr;m, 2.3 &mgr;m, 19.5 &mgr;m, and 0.1 D, respectively. Conclusions Swept‐source biometry showed high repeatability performance for all biometric parameters. The agreement of AL, ACD, and SE between swept‐source and PCI biometry as well as that of LT and CCT between swept‐source and OLCR biometry was excellent. It remains to be validated whether high repeatability shown by swept‐source biometry will result in better postoperative refractive outcomes. Financial Disclosure Drs. Blum and Sekundo are members of the Scientific Advisory Board of Carl Zeiss Meditec AG. Drs. Peter and Bühren are employees of Carl Zeiss Meditec AG.

Surface Quality of Porcine Corneal Lenticules after Femtosecond Lenticule Extraction

Purpose: To determine the surface characteristics of porcine corneal lenticules after Femtosecond Lenticule Extraction. Methods: The Carl Zeiss Meditec AG VisuMax® femtosecond laser system was used to create refractive corneal lenticules on 10 freshly isolated porcine eyes. The surface regularity on the corneal lenticules recovered was evaluated by assessing scanning electron microscopy images using an established scoring system. Results: All specimens yielded comparable score results of 5–7 points (SD = 0.59) per lenticule (score range minimum 4 to maximum 11 points). Surface irregularities were caused by tissue bridges, cavitation bubbles or scratches. Conclusion: The Femtosecond Lenticule Extraction procedure is capable of creating corneal lenticules of predictable surface quality. However, future studies should focus on the optimization of laser parameters as well as surgical technique to improve the regularity of the corneal stromal bed.

Presbyopia treatment using a femtosecond laser

ZusammenfassungDie Presbyopie ist die bei weitem häufigste Fehlsichtigkeit, die bis heute keiner befriedigenden dauerhaften Korrektur zugänglich ist. Alle bisherigen Versuche, eine operative Therapie der Presbyopie zu entwickeln, haben bislang zu keiner klinisch etablierten Methode geführt. Im Tierversuch gibt es Anhaltspunkte für eine Möglichkeit, mittels Niedrigenergie-Femtosekundenlaser-Impulsen (fs-Laser) die Elastizitätsveränderungen der Augenlinse therapeutisch zu beeinflussen. Mit fs-Laserimpulsen können innerhalb des Linseninneren sowohl im Tierversuch als auch bei menschlichen Linsen Schnitte erzeugt werden, die die Elastizität der Linse erhöhen. Durch diese Konzepte zur Behandlung der Presbyopie mittels fs-Laser-Impulsen entsteht die Forderung nach komplexeren Augenmodellen, die neben den optischen auch mechanische Eigenschaften des Auges modellieren. Diagnostische Instrumente zur umfassenden objektiven Bewertung der dynamischen Refraktionseigenschaften des Auges, um die Presbyopiestufe zu charakterisieren und spätere Therapieerfolge objektiv zu bewerten, werden entwickelt. Eine nichtinvasive Behandlung der Altersweitsichtigkeit könnte möglich werden.AbstractPresbyopia is by far the most common refractive error worldwide, with no permanent therapeutic option available. All efforts to restore accommodation by the use of surgery have not led to a generally accepted therapy. However, there is evidence from an animal model that the use of a femtosecond (fs) laser might influence the modulus of elasticity in the lens. Fs-laser impulses can create intralenticular disruption in animal eyes as well as human cadaver lenses and improve elasticity. The concept of treating presbyopia with fs-laser requires a new, complex theory combining the optical and the mechanical aspects of accommodation in the eye. Diagnostic tools for measuring optical change in power and geometrical modification as the eye views from far to near are needed to obtain objective clinical data. A non-invasive treatment of presbyopia to restore accommodation might be possible in the future.Presbyopia is by far the most common refractive error worldwide, with no permanent therapeutic option available. All efforts to restore accommodation by the use of surgery have not led to a generally accepted therapy. However, there is evidence from an animal model that the use of a femtosecond (fs) laser might influence the modulus of elasticity in the lens. Fs-laser impulses can create intralenticular disruption in animal eyes as well as human cadaver lenses and improve elasticity. The concept of treating presbyopia with fs-laser requires a new, complex theory combining the optical and the mechanical aspects of accommodation in the eye. Diagnostic tools for measuring optical change in power and geometrical modification as the eye views from far to near are needed to obtain objective clinical data. A non-invasive treatment of presbyopia to restore accommodation might be possible in the future.

Femtosecond laser treatment of the crystalline lens: a 1-year study of possible cataractogenesis in minipigs

BackgroundTo investigate the long-term stability and possible cataractogenesis after femtosecond laser treatment of the crystalline lens.MethodsThe crystalline lenses of ten Göttingen minipigs® underwent femtosecond laser treatment. During a subsequent 1-year follow-up, the pigs were monitored by means of slit-lamp examination of the anterior segment and Scheimpflug imaging of the lens.ResultsNo laser-induced cataractogenesis was observed during the 1-year follow-up. The laser pattern showed a stable appearance under all examination devices.ConclusionFemtosecond laser treatment seems to be no trigger for cataract formation. Moreover, the long-term stability of the laser pattern makes it suitable for applications such as presbyopia treatment.

Effect of a suction device for femtosecond laser on anterior chamber depth and crystalline lens position measured by OCT.

PURPOSE To investigate the position and stability of the crystalline lens after application of a suction device containing a contact lens and a vacuum unit for the treatment of presbyopia using a femtosecond laser. METHODS Twenty presbyopic (44.4+/-4.3 years) and 5 pre-presbyopic patients (31.6+/-3.8 years) were included. The anterior chamber depth, along with the position of the lens, was investigated before and after application of the suction device with optical coherence tomography (Visante OCT; Carl Zeiss Meditec AG). The type of suction device is routinely used for femtosecond LASIK with the VisuMax laser (Carl Zeiss Meditec AG). RESULTS In both groups, there was a reduction in anterior chamber depth of approximately 700 microm due to the suction device, and the anterior chamber depth achieved was stable. The maximum variation was 160 microm. At the periphery of the crystalline lens, there were movements up to 310 microm axially and 470 microm laterally. CONCLUSIONS The study proves that once the suction device has been applied, the crystalline lens is stable enough to undergo presbyopic laser therapy. However, the reduction in anterior chamber depth induced by the suction device showed significant individual variation. The exact position of the lens should therefore be measured immediately before laser surgery.

An in vitro study on focusing fs-laser pulses into ocular media for ophthalmic surgery

To investigate femtosecond (fs)‐laser patterns within ocular media for ophthalmic surgery.