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Innovative SMILE procedure from ZEISS successfully performed on more than 100,000 eyes
Micro-invasive refractive surgery becomes an established laser vision procedure for the correction of myopia. Clinical trial in the USA expanded.
JENA / Germany, 04.02.2014.
Two years after its international launch, the SMILE procedure developed by ZEISS has become the third generation of laser vision correction. More than 80,000 eyes worldwide have now been successfully treated using the micro-invasive method which offers improved predictability of the vision correction outcome without the need to create a corneal flap. The US FDA has approved expansion of the US clinical trial.
The SMILE procedure developed by ZEISS for refractive surgery stands for Small Incision Lenticule Extraction and combines state-of-the-art femtosecond laser technology and precise lenticule extraction providing a micro-invasive laser vision correction method. Unlike LASIK (Laser-Assisted in situ Keratomileusis), in which an excimer laser ablates tissue inside the cornea after opening the corneal surface by cutting a corneal flap, the SMILE procedure is performed without a flap. The ZEISS femtosecond laser VisuMax® is used to create a very thin disc of tissue (lenticule) inside the intact cornea, which can then be extracted through a small incision. An excimer laser is not required.
“With SMILE ophthalmic surgeons now for the first time have a refractive surgery procedure that provides great benefits for their patients with the least possible intervention: the cornea of the eye remains intact as much as possible; the predictability of the correction is very good. The results are convincing more and more physicians and patients around the world,” says Dr. Ludwin Monz, President and CEO of Carl Zeiss Meditec AG.
One of those physicians is Detlev R.H. Breyer, MD from the eye surgery clinic “Breyer & Kaymak” located in Düsseldorf. “SMILE is a very valuable addition to our clinic’s portfolio of procedures, as we can now treat patients on an even more individual basis, and less invasively. Our practice is happy about the increasing demand we are receiving for this procedure, thanks to many recommendations from satisfied SMILE patients.”
The SMILE procedure has also been documented in scientific publications as “predictable, effective and safe”, regardless of the patient’s age. Jesper Hjortdal, MD, DrMedSci, PhD from Aarhus University Hospital in Denmark concludes in one of his studies, on 670 eyes of 335 patients with myopia, that SMILE is not inferior in any way to the LASIK procedure in these three aspects,1 and was awarded the Waring Medal for outstanding contributions by the Journal of Refractive Surgery.
In the period after the surgery SMILE proves to be superior to the LASIK method: According to recent studies, inflammation was less common after SMILE procedures, and healing of the cornea was better2. The problem of dry eye syndrome often described following laser vision correction has also shown to be reduced after a SMILE procedure, as reported by Prof. Dan Z. Reinstein, MD from the London Vision Clinic, in several publications3: “As the nerve tracts of the cornea remain largely intact, the SMILE procedure is the least invasive of all refractive procedures. Various studies show that dry eye syndrome is a much rarer side-effect compared with LASIK.”
The refractive correction of vision defects using laser technology has established itself as a method to enable eligible patients to have a life without glasses. Over the past few years development has focused on making the treatment less risky. The micro-invasive SMILE can now be considered a third-generation procedure, after methods such as PRK (Photorefractive Keratectomy) and LASIK – it involves the least possible intervention with the cornea remaining as intact as possible.
The procedure was launched internationally in September 2011 and is established in key markets such as Europe, China and India. A clinical trial is currently underway in the USA. The first results were presented in April 2013 by Jon Dishler, MD, US Medical Monitor for the VisuMax IDE Study and the FDA approved expansion of the clinical trial in July 2013. “Based on the excellent safety and effectiveness of data submitted to the FDA on the first 79 subjects treated with the SMILE procedure and followed for at least three months, the FDA granted approval to expand the study to the full cohort of 360 subjects. This is an important milestone for the study,” said Dr. Dishler at the Annual Meeting of the American Academy of Ophthalmology (AAO) in New Orleans at the beginning of November. In December 2013 the FDA granted approval to extend the trial further to include myopia of up to –10.00 diopters. The clinical trial in the USA began in June 2012; Dr. Dishler presented the first results in April 2013.To date, a total of 255 patients have been treated within the scope of the trial, at five centers in the USA. Outside the USA there are more than 150 centers in 38 countries with more than 300 surgeons performing the SMILE procedure.
|Scientific rationale for why femtosecond laser intrastromal keratomileusis is the future of corneal refractive surgeryby Dan Z. Reinstein, M.D.
We are in the age of the femtosecond laser. Having first found
utility in creating a flap for LASIK procedures, it became clear that the
potential for other uses in eye surgery was significant. Most recently, cataract surgery femtosecond applications have been the focus of development for laser companies. Now with the clinical trial of the
VisuMax laser under way, a true refractive platform may be possible with only the use of a femtosecond laser. As with all new technology, there will no doubt be continued improvement, and we can expect that the results will improve. Is intrastromal keratomileusis the future of corneal refractive surgery? Dan Reinstein, M.D., makes a compelling case in this month’s “International outlook” column. One thing is certain: Refractive surgeons around the world will be watching this carefully. Read for yourself and form your own opinion.John Vukich, M.D.,
Figure 1: Diagrams of the intact stromal lamellae after LASIK (top) and SMILE (bottom) highlighting the anterior lamellae that remain intact after SMILE. The RST calculations are shown for a 500 μm cornea with a 100 μm ablation/lenticule and 120 μm flap/cap thickness. The LASIK RST of 280 μm consists only of posterior stroma. The SMILE RST has the same 280 μm of posterior stroma, but also has 70 μm of anterior stroma, for a total of 350 μm of stroma. However, since the anterior stroma is 50% stronger than posterior stroma, a further 35 μm can be added to make an effective total of 385 μmFigure 2: Diagrams demonstrating the
difference between SMILE (top) and LASIK (bottom) in how the two procedures affect the anterior corneal nerve plexusFigure 3: Mean corneal sensation for 39 eyes after SMILE compared with the corneal sensation after LASIK averaged over nine published studiesSource (all): Dan Z. Reinstein, M.D.
Ever since femtosecond lasers were first introduced into refractive surgery, the ultimate goal has been to create an intrastromal lenticule that can be manually removed in one piece, thereby circumventing the need for incremental photoablation by an excimer laser. Following the introduction of the VisuMax femtosecond laser (Carl Zeiss Meditec, Jena, Germany) in 2007, the intrastromal lenticule method was introduced in a procedure called femtosecond lenticule extraction (FLEx) in which a flap was created and lifted to allow the lenticule to be removed.
Advantages of ReLEx SMILE over LASIK
These new femtosecond intrastromal lenticule procedures offer a number of potential advantages.
1. Sekundo W, Kunert KS, Blum M. Small
Editors’ note: Dr. Reinstein practices at the London Vision Clinic, London, and is affiliated with the Department of Ophthalmology, Columbia University Medical College, New York, and the Centre Hospitalier National d’Ophtalmologie, Paris. He has financial interests with Carl Zeiss Meditec and ArcScan Inc. (Morrison, Colo.).