Evaluating the effect of pulse energy on femtosecond laser trabeculotomy (FLT) outflow channels for glaucoma treatment in human cadaver eyes.

BACKGROUND AND OBJECTIVES: Femtosecond laser trabeculotomy (FLT) creates aqueous humor outflow channels through the trabecular meshwork (TM) and is an emerging noninvasive treatment for open-angle glaucoma. The purpose of this study is to investigate the effect of pulse energy on outflow channel creation during FLT. MATERIALS AND METHODS: An FLT laser (ViaLase Inc.) was used to create outflow channels through the TM (500 µm wide by 200 µm high) in human cadaver eyes using pulse energies of 10, 15, and 20 µJ. Following treatment, tissues were fixed in 4% paraformaldehyde. The channels were imaged using optical coherence tomography (OCT) and assessed as full thickness, partial thickness, or not observable. RESULTS: Pulse energies of 15 and 20 µJ had a 100% success rate in creating full-thickness FLT channels as imaged by OCT. A pulse energy of 10 µJ resulted in no channels (n = 6), a partial-thickness channel (n = 2), and a full-thickness FLT channel (n = 2). There was a statistically significant difference in cutting widths between the 10 and 15 µJ groups (p < 0.0001), as well as between the 10 and 20 µJ groups (p < 0.0001). However, there was no statistically significant difference between the 15 and 20 µJ groups (p = 0.416). CONCLUSIONS: Fifteen microjoules is an adequate pulse energy to reliably create aqueous humor outflow channels during FLT in human cadaver eyes. OCT is a valuable tool when evaluating FLT.

A review of the epithelial and stromal effects of corneal collagen crosslinking.

Induced corneal collagen crosslinking and mechanical stiffening via ultraviolet-A photoactivation of riboflavin (UVA CXL) is now a common treatment for corneal ectasia and Keratoconus. Some effects of the procedure such as induced mechanical stiffening, corneal flattening, and cellular toxicity are well-known, but others remain more controversial. Authors report a variety of contradictory effects, and provide evidence based on individual results and observations. A full understanding of the effects of and mechanisms behind this procedure are essential to predicting its outcome. A growing interest in modifications to the standard UVA CXL protocol, such as transepithelial or accelerated UVA CXL, makes analyzing the literature as a whole more urgent. This review presents an analysis of both the agreed-upon and contradictory results reported and the various methods used to obtain them.

First-in-Human Safety Study of Femtosecond Laser Image-Guided Trabeculotomy for Glaucoma Treatment: 24-month Outcomes.

Purpose: Pilot study to evaluate adverse events and intraocular pressure (IOP)-lowering of a novel, noninvasive glaucoma procedure, femtosecond laser, image-guided, high-precision trabeculotomy (FLIGHT). Design: Prospective, nonrandomized, single-center, interventional, single-arm clinical trial. Participants: Eighteen eyes from 12 patients with open-angle glaucoma. Methods: Eighteen eyes from 12 patients underwent FLIGHT, creating a single channel measuring 500-µm wide by 200-µm high through the trabecular meshwork and into Schlemm's canal. Adverse events, IOP, and other parameters were evaluated out to 24 months. Main Outcome Measures: Outcomes were the rates and types of adverse events and the rate of postprocedure best-corrected visual acuity loss (≥ 2 lines) compared with baseline. Efficacy outcomes were reduction in mean intraocular pressure (IOP) with respect to baseline and the percentage of eyes with a ≥ 20% reduction in IOP. Results: Eighteen eyes from 12 patients were enrolled in the study; 11 patients (17 eyes) returned at 24 months. There were no serious adverse events related to the laser treatment. Well-defined channels were clearly visible at 24 months by gonioscopy and anterior segment OCT, with no evidence of closure. At 24 months, the mean IOP was reduced by 34.6% from 22.3 ± 5.5 to 14.5 ± 2.6 mmHg (P < 5e-5), with an average of 2.0 ± 1.2 hypotensive medications compared with 2.2 ± 1.1 at baseline (P = 0.22). Fourteen out of the 17 study eyes (82.3%) achieved a ≥ 20% reduction in IOP at 24 months when compared with baseline. Conclusion: The FLIGHT system demonstrated a favorable safety profile in this initial pilot study, with no device-related serious adverse events. The channels appeared patent at 24 months, indicating medium-term durability. Financial Disclosures: Proprietary or commercial disclosure may be found after the references.

Nonlinear optical corneal collagen crosslinking of ex vivo rabbit eyes.

PURPOSE: To determine whether riboflavin-induced collagen crosslinking (CXL) could be precisely achieved in the corneal stroma of ex vivo rabbit eyes using nonlinear optical excitation with a low numerical aperture lens and enlarged focal volume. SETTING: Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, USA. DESIGN: Experimental study. METHODS: The corneal epithelium was removed and the corneas were soaked in 0.5% riboflavin solution. Using a 0.1 numerical aperture objective, a theoretical excitation volume of 150 µm × 3 µm was generated using 1 W of 760 nm femtosecond laser light and raster scanned with 4.4 µm line separation at varying effective speeds over a 4.50 mm × 2.25 mm area. Corneal sections were examined for collagen autofluorescence. RESULTS: Collagen autofluorescence was enhanced 2.9 times compared with ultraviolet-A (UVA) CXL. Also, increasing speed was linearly associated with decreasing autofluorescence intensity. The slowest speed of 2.69 mm/s showed a mean of 182.97 µm ± 52.35 (SD) long autofluorescent scan lines axially in the central cornea compared with 147.84 ± 4.35 µm for UVA CXL. CONCLUSIONS: Decreasing dwell time was linearly associated with decreasing autofluorescence intensity, approaching that of UVA CXL at a speed of 8.9 mm/s. Using an effective speed of 8.9 mm/s, nonlinear optical CXL could be achieved over a 3.0 mm diameter area in fewer than 4 minutes. Further development of nonlinear optical CXL might result in safer, faster, and more effective CXL treatments. FINANCIAL DISCLOSURE: None of the authors has a financial or proprietary interest in any material or method mentioned.

Evaluation of the mechanical properties of the anterior lens capsule following femtosecond laser capsulotomy at different pulse energy settings.

PURPOSE: To evaluate and compare the mechanical properties of anterior capsule opening performed with femtosecond laser capsulotomy at different energy settings in ex vivo porcine anterior lens capsule specimens. METHODS: Twenty-five fresh porcine eyes per group were included in the study. Femtosecond laser capsulotomy was performed with three different pulse energy levels: 2 µJ (low energy group), 5 µJ (intermediate energy group), and 10 µJ (high energy group). The capsule openings were stretched with universal testing equipment until they ruptured. The morphologic profile of the cut capsule edges was evaluated using scanning electron microscopy. RESULTS: The high energy group had significantly lower rupture force (108 ± 14 mN) compared to the intermediate energy group (118 ± 10 mN) (P < .05) and low energy group (119 ± 11 mN) (P < .05), but the difference between the intermediate energy and low energy groups was not significant (P = .9479). The high energy group had significantly lower circumference stretching ratio (144% ± 3%) compared to the intermediate energy group (148% ± 3%) (P < .05) and low energy group (148% ± 3%) (P < .05), but the difference between the intermediate energy group and low energy group was not significant (P = .9985). Scanning electron microscopy images showed that the edge was only serrated with low and intermediate energy, but additional signs of collagen melting and denaturation were observed at high energy. CONCLUSIONS: Anterior capsule openings created at a high energy level were slightly weaker and less extensible than those created at low or intermediate levels, possibly due to the increased thermal effect of photo-disruption.

Comparison of the mechanical properties of the anterior lens capsule following manual capsulorhexis and femtosecond laser capsulotomy.

PURPOSE: To evaluate and compare the mechanical properties of anterior capsule openings performed with the continuous curvilinear capsulorhexis (CCC) technique and femtosecond laser capsulotomy (FLC) in ex vivo porcine lens capsule specimens. METHODS: Fresh porcine eyes were included in the study (CCC group, n = 50; FLC group, n = 30). The capsule openings were stretched with universal testing equipment until they ruptured. The rupture force and circumference stretching ratio were evaluated. The morphologic profile of the cut capsule edges was evaluated using scanning electron microscopy (SEM). RESULTS: The average rupture force was higher in the CCC group (median: 155 mN; interquartile range [IQR]: 129 to 201 mN; range: 71 to 294 mN) than in the FLC group (median: 119 mN; IQR: 108 to 128 mN; range: 91 to 142 mN) (P < .01, Mann-Whitney U test). The average circumference stretching ratio in the CCC group was greater (median: 150%; IQR: 146% to 156%; range: 136% to 161%) than in the FLC group (median: 148%; IQR: 145% to 150%; range: 141% to 154%) (P = .0468, Mann-Whitney U test). When less than 71 mN, no capsular tear occurred in either group. When less than 91 mN, no capsular tear occurred in the FLC group, whereas at 91 mN, the probability of capsular tears was 9% for the CCC group. SEM examination found that the CCC group had smooth edges, whereas those of the FLC group were gently serrated. CONCLUSIONS: According to the current results in a porcine eye model, FLC had less average resistance to capsule tear than CCC, but the weakest openings were seen in the CCC group.

Preclinical investigations of articular cartilage ablation with femtosecond and pulsed infrared lasers as an alternative to microfracture surgery.

Microfracture surgery is a bone marrow stimulation technique for treating cartilage defects and injuriesin the knee. Current methods rely on surgical skill and instrumentation. This study investigates the potential useof laser technology as an alternate means to create the microfracture holes. Lasers investigated in this study include an erbium:YAG laser (λ = 2.94 µm), titanium:sapphire femtosecond laser system (λ = 1700 nm), and Nd:glass femtosecond laser (λ = 1053 nm). Bovine samples were ablated at fluences of 8 to 18 J∕cm2 with the erbium:YAG laser, at a power of 300 ± 15 mW with the titanium:sapphire femtosecond system, and at an energy of 3 µJ∕pulse with the Nd:glass laser. Samples were digitally photographed and histological sections were taken for analysis. The erbium:YAG laser is capable of fast and efficient ablation; specimen treated with fluences of 12 and 18 J∕cm2 experienced significant amounts of bone removal and minimal carbonization with saline hydration. The femtosecond laser systems successfully removed cartilage but not clinically significant amounts of bone. Precise tissue removal was possible but not to substantial depths due to limitations of the systems. With additional studies and development, the use of femtosecond laser systems to ablate bone may be achieved at clinically valuable ablation rates.

Measurement of corneal elasticity with an acoustic radiation force elasticity microscope.

To investigate the role of collagen structure in corneal biomechanics, measurement of localized corneal elasticity with minimal destruction to the tissue is necessary. We adopted the recently developed acoustic radiation force elastic microscopy (ARFEM) technique to measure localize biomechanical properties of the human cornea. In ARFEM, a low-frequency, high-intensity acoustic force is used to displace a femtosecond laser-generated microbubble, while high-frequency, low-intensity ultrasound is used to monitor the position of the microbubble within the cornea. Two ex vivo human corneas from a single donor were dehydrated to physiologic thickness, embedded in gelatin and then evaluated using the ARFEM technique. In the direction perpendicular to the corneal surface, ARFEM measurements provided elasticity values of E = 1.39 ± 0.28 kPa for the central anterior cornea and E = 0.71 ± 0.21 kPa for the central posterior cornea in pilot studies. The increased value of corneal elasticity in the anterior cornea correlates with the higher density of interweaving lamellae in this region.

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.

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.

Evaluation of human sclera after femtosecond laser ablation using two photon and confocal microscopy.

Glaucoma is the second-leading cause of blindness worldwide and is often associated with elevated intraocular pressure (IOP). Partial thickness intrascleral channels can be created with a femtosecond laser operating at a wavelength of 1700 nm. Such channels have the potential to increase outflow facility and reduce elevated IOP. Analysis of the dimensions and location of these channels is important in understanding their effects. We describe the application of two-photon microscopy and confocal microscopy for noninvasive imaging of the femtosecond laser created partial-thickness scleral channels in human cadaver eyes. High-resolution images, hundreds of microns deep in the sclera, were obtained to allow determination of the shape and dimension of such channels. This demonstrates that concept of integrating femtosecond laser surgery, and two-photon and confocal imaging has the future potential for image-guided high-precision surgery in transparent and translucent tissue.

Finite element model of the temperature increase in excised porcine cadaver iris during direct illumination by femtosecond laser pulses.

In order to model the thermal effect of laser exposure of the iris during laser corneal surgery, we simulated the temperature increase in porcine cadaver iris. The simulation data for the 60 kHz FS60 Laser showed that the temperature increased up to 1.23°C and 2.45°C (at laser pulse energy 1 and 2 [micro sign]J, respectively) by the 24 second procedure time. Calculated temperature profiles show good agreement with data obtained from ex vivo experiments using porcine cadaver iris. Simulation results of different types of femtosecond lasers indicate that the Laser in situ keratomileusis procedure does not present a safety hazard to the iris.

Nonlinear optical macroscopic assessment of 3-D corneal collagen organization and axial biomechanics.

PURPOSE: To characterize and quantify the collagen fiber (lamellar) organization of human corneas in three dimensions by using nonlinear optical high-resolution macroscopy (NLO-HRMac) and to correlate these findings with mechanical data obtained by indentation testing of corneal flaps. METHODS: Twelve corneas from 10 donors were studied. Vibratome sections, 200 µm thick, from five donor eyes were cut along the vertical meridian from limbus to limbus (arc length, 12 mm). Backscattered second harmonic-generated (SHG) NLO signals from these sections were collected as a series of overlapping 3-D images, which were concatenated to form a single 3-D mosaic (pixel resolution: 0.44 µm lateral, 2 µm axial). Collagen fiber intertwining was quantified by determining branching point density as a function of stromal depth. Mechanical testing was performed on corneal flaps from seven additional eyes. Corneas were cut into three layers (anterior, middle, and posterior) using a femtosecond surgical laser system and underwent indentation testing to determine the elastic modulus for each layer. RESULTS: The 3-D reconstructions revealed complex collagen fiber branching patterns in the anterior cornea, with fibers extending from the anterior limiting lamina (ALL, Bowman's layer), intertwining with deeper fibers and reinserting back to the ALL, forming bow spring-like structures. Measured branching-point density was four times higher in the anterior third of the cornea than in the posterior third and decreased logarithmically with increasing distance from the ALL. Indentation testing showed an eightfold increase in elastic modulus in the anterior stroma. CONCLUSIONS: The axial gradient in lamellar intertwining appears to be associated with an axial gradient in the effective elastic modulus of the cornea, suggesting that collagen fiber intertwining and formation of bow spring-like structures provide structural support similar to cross-beams in bridges and large-scale structures. Future studies are necessary to determine the role of radial and axial structural-mechanical heterogeneity in controlling corneal shape and in the development of keratoconus, astigmatism, and other refractive errors.

Quantitative assessment of UVA-riboflavin corneal cross-linking using nonlinear optical microscopy.

PURPOSE: Corneal collagen cross-linking (CXL) by the use of riboflavin and ultraviolet-A light (UVA) is a promising and novel treatment for keratoconus and other ectatic disorders. Since CXL results in enhanced corneal stiffness, this study tested the hypothesis that CXL-induced stiffening would be proportional to the collagen autofluorescence intensity measured with nonlinear optical (NLO) microscopy. METHODS: Rabbit eyes (n = 50) were separated into five groups including: (1) epithelium intact; (2) epithelium removed; (3) epithelium removed and soaked in riboflavin, (4) epithelium removed and soaked in riboflavin, with 15 minutes of UVA exposure; and (5) epithelium removed and soaked in riboflavin, with 30 minutes of UVA exposure. Corneal stiffness was quantified by measuring the force required to displace the cornea 500 µm. Corneas were then fixed in paraformaldehyde and sectioned, and the collagen autofluorescence over the 400- to 450-nm spectrum was recorded. RESULTS: There was no significant difference in corneal stiffness among the three control groups. Corneal stiffness was significantly and dose dependently increased after UVA (P < 0.0005). Autofluorescence was detected only within the anterior stroma of the UVA-treated groups, with no significant difference in the depth of autofluorescence between different UVA exposure levels. The signal intensity was also significantly increased with longer UVA exposure (P < 0.001). Comparing corneal stiffness with autofluorescence intensity revealed a significant correlation between these values (R(2) = 0.654; P < 0.0001). CONCLUSIONS: The results of this study indicate a significant correlation between corneal stiffening and the intensity of collagen autofluorescence after CXL. This finding suggests that the efficacy of CXL in patients could be monitored by assessing collagen autofluorescence.

Temperature increase in porcine cadaver iris during direct illumination by femtosecond laser pulses.

PURPOSE: To measure the temperature rise in porcine cadaver iris during direct illumination by the femtosecond laser as a model for laser exposure of the iris during femtosecond laser corneal surgery. SETTING: Department of Ophthalmology, University of California-Irvine, Irvine, California, USA. DESIGN: Experimental study. METHODS: The temperature increase induced by a 60 kHz commercial femtosecond laser in porcine cadaver iris was measured in situ using an infrared thermal imaging camera at pulse energy levels ranging from 1 to 2 µJ (corresponding approximately to surgical energies of 2 to 4 µJ per laser pulse). RESULTS: Temperature increases up to 2.3 °C (corresponding to 2 µJ and 24-second illumination) were observed in the porcine cadaver iris with little variation in temperature profiles between specimens for the same laser energy illumination. CONCLUSIONS: The 60 kHz commercial femtosecond laser operating with pulse energies at approximately the lower limit of the range evaluated in this study would be expected to result in a 1.2 °C temperature increase and therefore does not present a safety hazard to the iris.

In vivo femtosecond laser subsurface scleral treatment in rabbit eyes.

BACKGROUND AND OBJECTIVES: The progression of glaucoma can be reduced or delayed by reducing intraocular pressure (IOP). The properties of femtosecond laser surgery, such as markedly reduced collateral tissue damage, coupled with the ability to achieve isolated subsurface surgical effects in the sclera, make this technology a promising candidate in glaucoma management. In this pilot study we demonstrate the in vivo creation of partial thickness subsurface drainage channels with the femtosecond laser in the sclera of rabbit eyes in order to increase aqueous humor (AH) outflow. STUDY DESIGN/MATERIALS AND METHODS: A femtosecond laser beam tuned to a 1.7 microm wavelength was scanned along a rectangular raster pattern to create the partial thickness subsurface drainage channels in the sclera of one eye of each of the four rabbits included in this pilot study. IOP was measured before and 20 minutes after the laser treatment to evaluate the acute effect of the procedure. RESULTS: OCT images verified the creation of the partial thickness subsurface scleral channels in the eyes of the in vivo rabbits. Comparison of pre- and postoperative IOP measurements in treated and control eyes revealed a reduction in the intraocular pressure due to the increased rate of AH outflow resulted in by the presence of the partial thickness scleral channels. CONCLUSIONS: The creation of partial thickness subsurface drainage channels was demonstrated in the sclera of in vivo rabbit eyes with a 1.7 microm wavelength femtosecond laser. Reduction in IOP achieved by the partial thickness channels suggests potential utility in the treatment of elevated IOP.

Temperature increase in human cadaver retina during direct illumination by femtosecond laser pulses.

PURPOSE: Femtosecond lasers have been approved by the US Food and Drug Administration for ophthalmic surgery, including use in creating corneal flaps in LASIK surgery. During normal operation, approximately 50% to 60% of laser energy may pass beyond the cornea, with potential effects on the retina. As a model for retinal laser exposure during femtosecond corneal surgery, we measured the temperature rise in human cadaver retinas during direct illumination by the laser. METHODS: The temperature increase induced by a 150-kHz iFS Advanced Femtosecond Laser (Abbott Medical Optics) in human cadaver retinas was measured in situ using an infrared thermal imaging camera. To model the geometry of the eye during the surgery, an approximate 11x11-mm excised section of human cadaver retina was placed 17 mm behind the focus of the laser beam. The temperature field was observed in 10 cadaver retina samples at energy levels ranging from 0.4 to 1.6 microJ (corresponding approximately to surgical energies of 0.8 to 3.2 microJ per pulse). RESULTS: Maximal temperature increases up to 1.15 degrees C (corresponding to 3.2 microJ and 52-second illumination) were observed in the cadaver retina sections with little variation in temperature profiles between specimens for the same laser energy illumination. CONCLUSIONS: The commercial iFS Advanced Femtosecond Laser operating with pulse energies at approximately the lower limit of the range evaluated in this study would be expected to result in a 0.2 degrees C temperature increase and do not therefore present a safety hazard to the retina.

Femtosecond laser ablation of the stapes.

A femtosecond laser, normally used for LASIK eye surgery, is used to perforate cadaveric human stapes. The thermal side effects of bone ablation are measured with a thermocouple in an inner ear model and are found to be within acceptable limits for inner ear surgery. Stress and acoustic events, recorded with piezoelectric film and a microphone, respectively, are found to be negligible. Optical microscopy, scanning electron microscopy, and optical coherence tomography are used to confirm the precision of the ablation craters and lack of damage to the surrounding tissue. Ablation is compared to that from an Er:YAG laser, the current laser of choice for stapedotomy, and is found to be superior. Ultra-short-pulsed lasers offer a precise and efficient ablation of the stapes, with minimal thermal and negligible mechanical and acoustic damage. They are, therefore, ideal for stapedotomy operations.

Femtosecond laser-assisted lamellar keratoplasty.

Lamellar keratoplasty consists of transplanting partial-thickness donor cornea onto a complementary recipient bed. Manual lamellar dissection is technically very difficult, time-consuming, and imprecise. Also, the manually-dissected lamellar interface often has topographical irregularities that may optically degrade the best-corrected visual acuity. The femtosecond clinical laser (IntraLase FS Laser, Irvine, CA) is a recent innovation that can be programmed to produce bladeless, precise lamellar cuts at any depth with accompanying trephination cuts for both anterior and posterior lamellar transplantation. Posterior laser cuts may be used to assist in deep lamellar endothelial keratoplasty or Descemet's stripping automated endothelial keratoplasty.

Femtosecond laser-assisted lamellar keratoplasty / Transplante lamelar auxiliado pelo laser de fentosegundo

Lamellar keratoplasty consists of transplanting partial-thickness donor cornea onto a complementary recipient bed. Manual lamellar dissection is technically very difficult, time-consuming, and imprecise. Also, the manually-dissected lamellar interface often has topographical irregularities that may optically degrade the best-corrected visual acuity. The femtosecond clinical laser (IntraLase FS LaserTM, Irvine, CA) is a recent innovation that can be programmed to produce bladeless, precise lamellar cuts at any depth with accompanying trephination cuts for both anterior and posterior lamellar transplantion. Posterior laser cuts may be used to assist in deep lamellar endothelial keratoplasty or Descemet's stripping automated endothelial keratoplasty.

A ceratoplastia lamelar consiste em transplante de espessura parcial da córnea doadora em um leito receptor complementar. A dissecção lamelar manual é técnica de difícil realização, imprecisa e que demanda tempo. Além disso, a interface lamelar freqüentemente apresenta irregularidade topográfica que pode comprometer a acuidade visual final. O laser clínico "femtosecond" (IntraLase FS LaserTM, Irvine, CA) é uma recente inovação que pode ser utilizado para produzir cortes lamelares precisos em qualquer profundidade da córnea, acompanhados de cortes verticais tanto para transplantes lamelares anteriores como posteriores sem a utilização de lâminas. Os cortes posteriores podem ser utilizados para a realização de ceratoplastia endotelial lamelar profunda ou ceratoplastia endotelial com remoção da membrana de Descemet.