Femtosecond laser–assisted cataract surgery
TL;DR: The available laser platforms are reviewed and the necessary modifications in cataract surgery technique and the logistics of incorporating a femtosecond laser into one's practice are discussed.
Abstract: Femtosecond laser-assisted cataract surgery provides surgeons an exciting new option to potentially improve patient outcomes and safety. Over the past 2 years, 4 unique laser platforms have been introduced into the marketplace. The introduction of this new technology has been accompanied by a host of new clinical, logistical, and financial challenges for surgeons. This article describes the evolution of femtosecond laser technology for use in cataract surgery. It reviews the available laser platforms and discusses the necessary modifications in cataract surgery technique and the logistics of incorporating a femtosecond laser into one's practice.
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TL;DR: The recent advances made in the development of TPE nanoparticles for cancer PDT are summarized in detail, and the existing challenges as well as the future perspectives are also discussed.
Abstract: Two-photon excitation (TPE) nanoparticle-based photosensitizers (PSs) that combine the advantages of TPE and nanotechnology have emerged as attractive therapeutic agents for near-infrared red (NIR) light excited photodynamic therapy (PDT) for cancer treatment. TPE PDT is characterized by nonlinear absorption of two relatively low-energy photons of NIR light with the resulting emission of high-energy visible light. This high-energy light can sensitize oxygen to produce cytotoxic reactive oxygen species (ROS) and singlet oxygen (1O2) which can kill cancer cells. The long-wavelength light used to excite TPE NPs allows for deeper tissue penetration to achieve efficient PDT of deep-seated tumors. Moreover, TPE nanoparticles normally have large two-photon absorption (TPA) cross-sections, which hold great potential as efficient two-photon donors in PDT. In this review, we will summarize the recent advances made in the development of TPE nanoparticles for cancer PDT. Five different TPE nanoparticles, including quantum dots (QDs), carbon nanomaterials, silica nanoparticles, gold nanomaterials, and polymer nanoparticles, are summarized in detail, and the existing challenges as well as the future perspectives are also discussed.
405 citations
TL;DR: The femtosecond laser produced capsulotomies that were more precise, accurate, reproducible, and stronger than those created with the conventional manual technique.
Abstract: RESULTS: Laser-created capsulotomies were significantly more precise in size and shape than manually created capsulorhexes. In the patient eyes, the deviation from the intended diameter of the resected capsule disk was 29 mm G 26 (SD) for the laser technique and 337 G 258 mm for the manual technique. The mean deviation from circularity was 6% and 20%, respectively. The center of the laser capsulotomies was within 77 G 47 mm of the intended position. All capsulotomies were complete, with no radial nicks or tears. The strength of laser capsulotomies (porcine subgroup) decreased with increasing pulse energy: 152 G 21 mN for 3 mJ, 121 G 16 mN for 6 mJ, and 113 G 23 mN for 10 mJ. The strength of the manual capsulorhexes was 65 G 21 mN. CONCLUSION: The femtosecond laser produced capsulotomies that were more precise, accurate, reproducible, and stronger than those created with the conventional manual technique. Financial Disclosure: The authors have equity interest in OptiMedica Corp., which manufactures the femtosecond laser cataract system.
325 citations
Cites background from "Femtosecond laser–assisted cataract..."
...Femtosecond technology has the ability to facilitate and optimize manual portions of cataract surgery.(15,17,18) The benefits are increased safety and improved refractive outcomes....
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TL;DR: In the authors' experience, the surgical outcomes and safety of LCS improved significantly with greater surgeon experience, development of modified techniques, and improved technology.
235 citations
232 citations
TL;DR: The femtosecond laser did not add to the endothelial damage caused by cataract surgery and might be beneficial in eyes with low preoperative endothelial cell values (eg, cornea guttata cases).
Abstract: Purpose To quantify changes in endothelial cell counts and corneal thickness measurements in patients having standard phacoemulsification compared with femtosecond laser–assisted cataract removal. Setting Ruhr University Eye Clinic, Bochum, Germany. Design Prospective randomized intraindividual cohort study. Methods One eye of each patient had standard phacoemulsification (control group) and the other eye had femtosecond laser–assisted phacoemulsification (study group), both with intraocular lens implantation. Pulsed ultrasound energy was used for phacoemulsification. Noncontact endothelial cell microscopy and corneal pachymetry were performed preoperatively and 1 day, 3 to 4 days, 7 to 10 days, 50 to 60 days, and 90 to 100 days postoperatively. Results The mean endothelial cell loss was 7.9% ± 7.8% (SD) 1 week postoperatively and 8.1% ± 8.1% 3 months postoperatively in the study group and 12.1% ± 7.3% and 13.7% ± 8.4%, respectively, in the control group. The mean relative change in corneal thickness from the preoperative values was −0.0% ± 1.9% at 1 day, 2.8% ± 1.8% at 1 week, and 3.3% ± 1.7% at 3 months in the study group and −0.9% ± 2.3%, 2.4% ± 1.5%, and 3.2% ± 1.4%, respectively, in the control group. Conclusion The femtosecond laser did not add to the endothelial damage caused by cataract surgery and might be beneficial in eyes with low preoperative endothelial cell values (eg, cornea guttata cases). Financial Disclosure Dr. Dick is a member of the medical advisory board of Optimedica Corp. No other author has a financial or proprietary interest in any material or method mentioned.
203 citations
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TL;DR: 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.
Abstract: 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.
510 citations
"Femtosecond laser–assisted cataract..." refers background in this paper
...Femtosecond laser technology, introduced clinically for ophthalmic surgery in 2001 as a new technique for creating lamellar flaps in laser in situ keratomileusis (LASIK), has recently been developed into a tool for cataract surgery.(3) Given the recent introduction of this technology, the conventional nomenclature for these procedures is inconsistent....
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TL;DR: Readingily available surgical services capable of delivering good vision rehabilitation must be acceptable and accessible to all in need, no matter what their circumstances, and to establish and sustain these services requires comprehensive strategies that go beyond a narrow focus on surgical technique.
Abstract: Cataract prevalence increases with age. As the world's population ages, cataract-induced visual dysfunction and blindness is on the increase. This is a significant global problem. The challenges are to prevent or delay cataract formation, and treat that which does occur. Genetic and environmental factors contribute to cataract formation. However, reducing ocular exposure to UV-B radiation and stopping smoking are the only interventions that can reduce factors that affect the risk of cataract. The cure for cataract is surgery, but this is not equally available to all, and the surgery which is available does not produce equal outcomes. Readily available surgical services capable of delivering good vision rehabilitation must be acceptable and accessible to all in need, no matter what their circumstances. To establish and sustain these services requires comprehensive strategies that go beyond a narrow focus on surgical technique. There must be changes in government priorities, population education, and an integrated approach to surgical and management training. This approach must include supply of start-up capital equipment, establishment of surgical audit, resupply of consumables, and cost-recovery mechanisms. Considerable innovation is required. Nowhere is this more evident than in the pursuit of secure funding for ongoing services.
453 citations
"Femtosecond laser–assisted cataract..." refers background in this paper
...TheWorldHealth Organization estimates this number will increase to 32 million by the year 2020 as the over65 population doubles worldwide between 2000 and 2020.(2) Globally, more than 3000 eye surgeons (more than 1000 United States surgeons) have been trained....
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TL;DR: The femtosecond laser produced capsulotomies that were more precise, accurate, reproducible, and stronger than those created with the conventional manual technique.
Abstract: RESULTS: Laser-created capsulotomies were significantly more precise in size and shape than manually created capsulorhexes. In the patient eyes, the deviation from the intended diameter of the resected capsule disk was 29 mm G 26 (SD) for the laser technique and 337 G 258 mm for the manual technique. The mean deviation from circularity was 6% and 20%, respectively. The center of the laser capsulotomies was within 77 G 47 mm of the intended position. All capsulotomies were complete, with no radial nicks or tears. The strength of laser capsulotomies (porcine subgroup) decreased with increasing pulse energy: 152 G 21 mN for 3 mJ, 121 G 16 mN for 6 mJ, and 113 G 23 mN for 10 mJ. The strength of the manual capsulorhexes was 65 G 21 mN. CONCLUSION: The femtosecond laser produced capsulotomies that were more precise, accurate, reproducible, and stronger than those created with the conventional manual technique. Financial Disclosure: The authors have equity interest in OptiMedica Corp., which manufactures the femtosecond laser cataract system.
325 citations
TL;DR: Properly sized, shaped, and centered femtosecond laser capsulotomies resulted in better overlap parameters that help maintain proper positioning of the IOL.
Abstract: 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 signifi cantly higher in the fi rst week and month. Signifi cantly higher values of capsule overlap over 1 year and circularity in the fi rst week showed more regular femtosecond capsulotomies. Horizontal IOL decentration was statistically signifi cantly higher in the CCC group over 1 year. A signifi cant 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 signifi cant predictors of horizontal decentration. Vertical diameter showed signifi cant 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 signifi cant 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. [J Refract Surg.
271 citations
TL;DR: A more precise, reproducible and automated way to remove cataracts by combining the precise cuts of a laser with the imaging sophistication of optical coherence tomography, a method that uses interference of coherent light scattered by biological tissues to create three-dimensional images of their internal structure.
Abstract: About one-third of people in the developed world will undergo cataract surgery in their lifetime. Although marked improvements in surgical technique have occurred since the development of the current approach to lens replacement in the late 1960s and early 1970s, some critical steps of the procedure can still only be executed with limited precision. Current practice requires manual formation of an opening in the anterior lens capsule, fragmentation and evacuation of the lens tissue with an ultrasound probe, and implantation of a plastic intraocular lens into the remaining capsular bag. The size, shape, and position of the anterior capsular opening (one of the most critical steps in the procedure) are controlled by freehand pulling and tearing of the capsular tissue. Here, we report a technique that improves the precision and reproducibility of cataract surgery by performing anterior capsulotomy, lens segmentation, and corneal incisions with a femtosecond laser. The placement of the cuts was determined by imaging the anterior segment of the eye with integrated optical coherence tomography. Femtosecond laser produced continuous anterior capsular incisions, which were twice as strong and more than five times as precise in size and shape than manual capsulorhexis. Lens segmentation and softening simplified its emulsification and removal, decreasing the perceived cataract hardness by two grades. Three-dimensional cutting of the cornea guided by diagnostic imaging creates multiplanar self-sealing incisions and allows exact placement of the limbal relaxing incisions, potentially increasing the safety and performance of cataract surgery.
255 citations