FEMTO-LASIK and BEYOND - Carl Zeiss, Inc.

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14 Ophthalmology WORLD REPORT tures of Femto-DALK and Femto-DSEK procedures and showed results for the VisuMax-ALK done for a post- PRK scarring. Post-op a 20/40 was obtained. He then showed a second patient with granular dystrophy and previous PRK with 20/60. The patient attained 20/40 unaided on postop day 1. In the view of Dr Tan, stromal bed quality, rim cut quality and accuracy of depth with femtosecond can exceed microkeratome quality but further optimization is needed. The endothelial morphology appears unaffected in the presence of laser ablation 150 microns from Descemet’s membrane. “Femtosecond laser ablation of the deep corneal stroma is close to being a viable alternative to microkeratome for donor preparation for DSEK and DALK. The next major advance we would like to see is to have a topographic link-up using anterior segment optical coherence tomography (AS-OCT) for accurate ablation profiles in reference to the posterior corneal surface. I think the femtosecond laser for DSEK and DALK are currently on horizon now,” he said. Singapore ReLEx Study: Dr Tan discussed the results of 30 ReLEx flex and 10 ReLEx smile cases of which 17 were analyzed. There was no algorithm adjustment. All cases were followed up for at least 1 month and 33 for 3 months. Speaking about the wide range of myopia, he said, “We went up to -10D and the average mean spherical equivalent was about -5.5D. The range was up to -9.75D and cylinder went up to -2.75D.” At 1 month postoperative, the mean spherical equivalent was 0.33. This hyperopic mean was good as most patients were young. And at 3 months postoperatively (33 eyes), the mean spherical equivalent was 0.22 (1.75 to -0.63). There was a case of hyperopic surprise and there wasn’t much myopic regression. Speaking about safety, he said that there does occur loss of lines. The results though are far better at 3 months. He shared his learning experience about suction loss in a 30 year old female, -8.75D/-1.25D. According to him, the ReLEx was stable and predictable without nomogram adjustments unlike the excimer laser nomograms. Talking about the reasonable efficacy he said that the results at 3 months were appreciable with 95% at 1D visual acuity. ReLEx smile results (6 eyes): These had a full ReLEx ablation profile, but the flap was only partially opened (about 1/3) and the lenticule extracted. According to him, “Enhancement could be done and it was easier.” The encouraging results seemed better than ReLEx. He further explained that the advantage of ReLEx smile was the easier enhancement.“I shifted the hinge to 160 degrees, as I am a right-handed surgeon,” he said. Comparing these with ReLEx, he said that ReLEx smile is a bit more challenging. He feels that ReLEx smile is good in the hands of surgeons who are experienced. For an average surgeon, who has not done many cases, there is a learning curve. He showed the various dissectors they have used in lamellar surgery and his favored DSAEK forceps. He shared a video of the ReLEx smile procedure and showed how centration is the key to visual acuity. ReLEx experiences and research at SERI: According to Dr Tan, ReLEx seems to be a promising new modality which may well challenge the superiority of LASIK, further clinical studies including direct comparison with LASIK are underway. Early clinical results with no nomogram adjustment appear to confirm good refractive efficacy, predictability, stability and safety though more cases need to be done. Preliminary results of ReLEx smile are also highly promising, with major advantages of better tectonic strength and possibly less dry eye and ocular surface disturbance. Lastly, the potential reversibility of ReLEx procedures may be a reality. “We have a cornea wound healing laboratory at the Singapore Eye Research Institute and the main role is to explore new surgical and therapeutic modalities for selective lamellar keratoplasty and corneal lamellar laser refractive surgery. We do have facilities for small and large animal primates with dedicated ophthalmic theatres, surgical microscopes, confocal microscopy, AS- OCT, immunohistochemistry, range of methodologies like EM, microkeratome, femtosecond laser and excimer laser platforms. He also said that the VisuMax platform is a part of the Translational Clinical Research (TCR) Flagship Program (TRIOS) funded by Government National Research Foundation Grant in collaboration with Carl Zeiss Meditec and discussed the changing trends of selective lamellar keratoplasty at SNEC. Storage of lenticules: He discussed the potential of reversibility of ReLEx and shared that SERI has filed a patent (#61/382,037) for the technique of storage of lenticules following femtosecond refractive lenticule procedures. SERI studies in rabbit eyes: SERI is experimenting in rabbit eyes for Femto-LASIK and ReLEx. Dr Tan showed the comparable results of in-vivo confocal microscopy for lamellar interface and anterior stroma in LASIK and ReLEx. He then discussed the ongoing studies to investigate the various markers for inflammation (CD 11b), cell proliferation (Ki-67), wound healing response (Fibronectin) and cell death. He showed the ReLExlenticule re-implantation technique wherein the lenticule placed on RGP CL and stored at -80 degree centigrade was replaced in correct anatomical orientation at 1 month after a flap relift. “We have tested the proof of concept that we can re-implant at least in rabbits,” he affirmed. He showed the topographies before ReLEx, 3 days after ReLEx and 3 days and 7 days after re-implantation of lenticule. He showed the AS-OCT imaging obtained after reimplantation
June 2012 Supplement 15 Continued from P13 >> and the results of in-vivo confocal at the anterior flap interface, lenticule lamellae and the posterior flap interface, 3 days and 7 days after re-implantation of the lenticule. Non-human primate model: Dr Tan said that ReLEx study had been initiated in monkeys at SERI and these should now prove the proof of concept of reversibility of ReLEx. He then showed the averaged topographies from 3 non-human primates (-6D treatment) before ReLEx and 3 days and 7 days after ReLEx. International Refractive User Symposium Kuala Lumpur, Malaysia In 2009, Prof Reinstein published the results for the combined corneal topography and corneal wavefront in treatment of corneal irregularity and refractive error in LASIK or PRK using MEL 80 and CRS-Master. Here, he reported a 41% decrease in spherical aberration and a 21% reduction in HORMS. Sharing the graphical record of attempted vs achieved spherical equivalent, he elaborated on the accuracy of the MEL 80 in high myopia. Seventy-one percent of the eyes were within +/- 0.5D and 94% within +/-1D. He shared the results of monocular efficacy in 127 eyes (excluding eyes not intending plano). Pre-op only 83% had 20/20 and postop uncorrected 90% had 20/20. “That is excellent,” he said. Then talking about safety (BSCVA) in 220 eyes, he said, “No loss of two lines. Very little loss of one line.” There was no change in 40% and 52% gained one line. According to him, the contrast sensitivity increased statistically significantly for only the higher frequencies. The stability was also maintained at 24 months. ReLEx smile: The New Application Prof Osama Ibrahim on “ReLEx: Clinical Update (ReLEx flex and ReLEx smile). My Experience with VisuMax” “ReLEx smile is a real innovation and a real challenge. It maintains the biomechanical integrity of the cornea in the anterior surface which actually is most important.” High myopia: Contrast Sensitivity Experience with VisuMax: Prof Ibrahim shared videos of the ReLEx flex and ReLEx smile procedures and said that “the VisuMax procedure was simply tissue removal rather than tissue ablation”. He specified the direction of scanning and how it is best to remain above the lenticule when making the flap. Sharing a video for ReLEx smile and explaining the correction of higher errors, he said that the technique is very simple and he ensures that he “remains anterior all the time”. “I go to one part and leave the other part as a counterpart. I use a very thin flap and can go up to 90µm,” he added. Study results: He shared the results of analysis of 189 eligible eyes (120 female and 69 males) that were mostly cases with high errors, higher even than -10D. The mean High myopia: Stability Summary: According to Prof Reinstein, one should know the spherical aberration induction per diopter, measure pre-op spherical aberration and know if the spherical aberration may cross the threshold. If crossing the threshold, one can do a spherical aberration pre-compensation or use a two-stage procedure, i.e. the wavefront-topograph-guided repair if necessary as second treatment. He cautioned with predicting the RST. “Pachymetry is best done with a high repeatability instrument. It is best to use a high reproducibility flap creation technique and always include the flap thickness bias,” Prof Reinstein concluded.
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