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Review Cataract Surgery Management of Astigmatism with the LENSAR Laser System with Streamline Mark Packer Mark Packer MD Consulting, Inc., Boulder, CO, US M anagement of astigmatism at the time of cataract or refractive lens surgery has evolved to include arcuate keratotomy and toric intraocular lens (IOL) implantation. Integration of preoperative corneal diagnostic instrumentation via Streamline digital wireless connectivity to the LENSAR™ femtosecond laser (LENSAR Inc., Orlando, FL, US) now allows improved precision and accuracy of arcuate incision and toric IOL alignment, eliminating a significant source of error in astigmatism correction. Use of a pre-programmed, surgeon- defined nomogram for arcuate incision construction, based on transmitted data from preoperative corneal analysis, permits further efficiency and reduction of transcription error. Toric IOL alignment is currently facilitated with IntelliAxis™ (LENSAR Inc., Orlando, FL, US) corneal marks. Management of astigmatism at the time of cataract surgery provides the refractive benefit of reduced dependence on glasses and sets the stage for correction of presbyopia Keywords Femtosecond laser, astigmatism, keratotomy, arcuate incision, limbal relaxing incision, toric intraocular lens Disclosure: Mark Packer is a consultant to LENSAR, Inc., Advanced Vision Science, Inc., Rayner Intraocular Lenses, Ltd., Bausch & Lomb (Valeant Pharmaceuticals), Medical Monitor, Alcon Research, Ltd., Chief Medical Officer, Equity Holder, i-Optics Corporation (Cassini USA), Chief Medical Officer, Equity Holder, International Biomedical Devices, Inc., STAAR Surgical, Inc., ClearSight, LLC, and Keranova. Compliance with Ethics: This study involves a review of the literature and did not involve any studies with human or animal subjects performed by any of the authors. Authorship: All named authors meet the International Committee of Medical Journal Editors (ICMJE) criteria for authorship of this manuscript, take responsibility for the integrity of the work as a whole, and have given final approval to the version to be published. Open Access: This article is published under the Creative Commons Attribution Noncommercial License, which permits any noncommercial use, distribution, adaptation, and reproduction provided the original author(s) and source are given appropriate credit. Received: August 9, 2017 Accepted: October 6, 2017 Citation: US Ophthalmic Review, 2017;10(2):99–103 Corresponding Author: Mark Packer, Mark Packer MD Consulting, Inc.,1400 Bluebell Ave, Boulder, CO 80302. E: Support: The publication of this article was supported by LENSAR., Inc. Through the centuries, ceaseless innovation has advanced cataract surgery – the most frequently performed operation on earth – from Daviel’s lens extraction, to Ridley’s intraocular lens (IOL) implantation, to Kelman’s phacoemulsification, and now to femtosecond laser assisted techniques. 1 Femtosecond laser surgery represents the marriage of two technologies: ocular imaging and laser photolysis. Most lasers depend on intraoperative optical coherence tomography imaging. The LENSAR™ femtosecond laser (LENSAR Inc., Orlando, Fl, US) utilizes proprietary augmented reality (AR) imaging and anterior segment biometry based on scanning structured illumination. Super luminescent diode technology provides the illumination for AR and scans at a variable rate depending on the target structure, ensuring optimal contrast for structures with higher light scatter, such as the cornea, as well as for those with little scatter, such as the posterior lens capsule. The 3D-AR software locates anatomic interfaces including the pupil, anterior and posterior corneal surfaces and the anterior and posterior lens capsule. The multiple images are collated using optical ray tracing techniques to generate an exact 3D reconstructed model of the anterior segment. In the LENSAR system, intraoperative imaging through structured illumination allows reconstruction of a 3D model of the anterior segment of the eye, which is used to guide laser incisions. 2 In addition to intraoperative imaging, wireless digital communication technology now permits integration of preoperative imaging into laser guidance. Recent US Food and Drug Administration (FDA) 510(k) clearances have demonstrated the utility of linkage between preoperative diagnostic instruments and the LENSAR laser, including the Cassini Corneal Shape Analyzer (Cassini, The Hague, The Netherlands), the Corneal Analyzer OPD-Scan III (Nidek, Aichi, Japan), the Aladdin (Topcon Corporation, Tokyo, Japan) and both the Pentacam ® HR and the Pentacam ® AXL (Oculus, Wetzlar, Germany). The key to these linkages is iris registration, the accurate mapping and matching of iris features from the preoperative image captured in the clinic to the intraoperative image captured through the laser optics. Iris registration, based on high definition preoperative infrared images obtained with these corneal diagnostic instruments, allows precise correlation of corneal topographic and total corneal astigmatic data with laser treatment, opening the way for accurate correction of corneal astigmatism. Correction of corneal astigmatism represents the entry point to refractive cataract surgery because it is prerequisite to achieving spectacle independence for the majority of surgical candidates. The introduction of toric multifocal and toric extended depth of focus IOL optical designs has raised the bar for correction of astigmatism and presbyopia at the time of cataract surgery; however, demonstration of the effectiveness of toric IOLs for correction of lower levels of corneal astigmatism, particularly <1.00 D, has remained elusive. For example, approved labeling for the Tecnis ® Toric IOL TOU CH MED ICA L MEDIA 99