Eyeworld

44 | EYEWORLD | SUMMER 2024 R EFRACTIVE Contact Chu: yrchu@chuvision.com Manche: cornea@stanford.edu Mehta: jodmehta@gmail.com Relevant disclosures Chu: Bausch + Lomb, Carl Zeiss Meditec Manche: Carl Zeiss Meditec, Johnson & Johnson Vision Mehta: Carl Zeiss Meditec, Johnson & Johnson Vision, Zeimer Johnson & Johnson Vision launched its Elita Femtosecond Laser, which is approved in the U.S. to create LASIK flaps and is under investigation for myopia correction via lenticule extraction in a procedure called SILK (smooth incision lenticule keratomileusis). Edward Man- che, MD, said this laser operates at 10 MHz and uses a very short pulse duration of approximate- ly 150 nJ and low energy of less than 45 nJ. "Lower energy levels have been associated with faster visual recovery in numerous peer-re- viewed papers in the published literature. Line and spot spacing is approximately 1 micron on the Elita system," Dr. Manche said. "This allows for contiguous spot placement, which results in a very smooth optical surface and allows ease of dissection of the lenticule." Dr. Manche also noted that the lenticules with the Elita laser are biconvex in shape with the refractive cut on both the anterior and pos- terior surface of the lenticule, a symmetry that he said may allow for a better fit after lenticule removal with fewer folds in Bowman's layer. Dr. Manche is part of the FDA clinical trial for the Elita system to perform lenticule ex- traction in the U.S. The first phase of the study enrolled 49 participants for feasibility. The sec- ond phase of the study, which began in the first quarter of this year, will enroll up to 400 par- ticipants at up to 10 U.S. sites. In the U.S., Dr. Manche said the company is targeting sphere up to –10 D and astigmatism up to –5 D. Dr. Manche said the lenticule dissection with SILK is easier than the current SMILE procedure and should have an easier learning curve, which he thinks could help adoption. Jod Mehta, MD, spoke about clear incision lenticule extraction (CLEAR) being developed by Ziemer with its FEMTO LDV Z8 and the new FEMTO Z8 NEO laser. Dr. Mehta said the laser uses a low energy, and the applanation on the cornea is flat, as opposed to curved. The advan- tages of CLEAR are a little more customization and improved surgeon learning curve, he said. The laser can create two incisions: one that opens in the anterior plane and the other that opens to the posterior plane. This will help with delineating the lenticule's two planes, which Dr. Mehta said was among the toughest parts of the learning curve for surgeons new to the proce- dure. Once the surgeon is more experienced, he said they can switch to a single incision and de- lineating the two planes from there. The CLEAR procedure also is not dependent on patient cooperation for fixation. With the Ziemer laser, the surgeon can mark the cornea and move the system to that position, Dr. Mehta said. "Those are the current advantages," Dr. Mehta said. "Going forward one of the newer things that will be coming out is the ability to link the laser to the tomography unit so you can have a tomography-guided procedure. That's designed to automate the centration and the torsional control straight away. The laser would automatically move the lenticule to the desired position." Dr. Manche and Dr. Mehta both said it's an advantage for so many companies to be work- ing on lenticule extraction capabilities. "I think it is great to have additional options when performing keratorefractive lenticule ex- traction," Dr. Manche said. "Carl Zeiss Meditec has done an incredible job developing SMILE. That being said, SMILE on the VisuMax femto- second laser has been the only option available for keratorefractive lenticule extraction for more than a decade. Competition spurs innovation, and this should be true with keratorefractive lenticule extraction. We have seen technological advances with excimer laser technology such as wavefront-guided ablations, topography-guided ablations, tracking, and iris registration over the years. I think that competition should lead to more rapid advances in femtosecond lasers used for keratorefractive lenticule extraction surgery. We have already seen this happening with faster lasers, post-docking centration, and cyclotor- sional adjustments." Editors' note: This article is not intended to reflect the full breadth of innovation occurring in corneal refractive surgery. It focuses on select tech- nologies as advised by the EyeWorld Refractive Editorial Board. continued from page 43

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