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Flapless laser vision correction technique offers notable advantages
A femtosecond laser creates a lenticule within the corneal stroma that is removed through a small incision.
ABU DHABI — In ReLEx smile, instead of a corneal flap, an intrastromal lenticule is created in the intact cornea and removed through a small incision. This allows for a high range of refractive correction without pain, flap-related complications or induced astigmatism, according to a surgeon.
Rupal Shah, MS, presented clinical results with ReLEx smile, a procedure that is used with the VisuMax femtosecond laser (Carl Zeiss Meditec), at an industry symposium during the World Ophthalmology Congress.
“ReLEx smile is PRK without pain and LASIK without [the] flap,” Shah said.
The femtosecond laser creates a lenticule within the corneal stroma, corresponding with the amount of refractive error to be corrected. The lenticule is then removed through a small incision performed by the same laser.
According to Shah, it is easy to extract the lenticule, even through a 3-mm incision.
“With a blunt instrument, you separate the lenticule from the overlying stroma, find its edge to go underneath and separate it posteriorly, then you pull it out,” she said.
The procedure is performed under topical anesthesia. There is no need to change stations, and the same operating microscope is used for the entire procedure. An integrated slit lamp further aids visualization.
The VisuMax laser uses a curved contact glass on the cornea, unlike other femtosecond lasers that hold on to the sclera to achieve suction. As a result, less IOP increase is induced.
Benefits
With the 500-kHz laser, the procedure lasts about 25 seconds.
“You let the cornea remain undisturbed throughout the procedure, and at the end ... it ‘smiles’ back at you,” Shah said.
No red eye is seen postoperatively. The day after the procedure, the eye looks as if it were untouched, and the patient can return to work.
ReLEx smile is attractive for patients because they like the idea of a “no blade, no flap, no pain” procedure, Shah said. Flapless surgery removes the potential complications of a flap, and pain is avoided because lenticule creation is done by femtosecond laser internally. The epithelium and the corneal surface are left nearly untouched, which leads to a lower healing response.
“Doing a small incision rather than a flap also means reducing the issue of dry eye and not affecting corneal biomechanics,” Shah said. “Two of the main concerns of LASIK surgery are avoided.”
However, results must at least match those for LASIK to justify moving away from what has been the gold standard for many years, she said.
Results
Between August 2008 and September 2011, Shah treated 1,500 eyes with ReLEx smile. During this period, the VisuMax laser was upgraded from 200 kHz to 500 kHz, and different scanning patterns and ablation profiles were introduced.
“In reviewing our results, we divided the patients into three groups with different levels of myopia, up to –10 D,” she said. “The greatest advantages were seen in the high myopic group, where the excimer laser fails in many cases. The excimer laser offers a very high standard in the correction of low to moderate myopia, but in my experience ReLEx gives better results when myopia is high.”
At 1 month, best corrected visual acuity was unchanged in most patients and vision improved for many, especially the high myopia group. More than 82% of patients achieved 20/20 or better uncorrected vision. These results remained stable throughout follow-up.
“If patients do well over the first week, they remain remarkably stable over time,” Shah said.
Predictability was high, with 90% of patients within ±0.5 D of intended correction in the low myopia group and 80% of patients within ±0.5 D in the high myopia group. Almost all eyes were within ±1 D.
“We are now trying to extend the range of treatment to –14 D for myopia and to hyperopia. We are also trying to find out if re-treatments can be done with the femtosecond laser or we still have to depend on the excimer laser,” Shah said.
Re-treating by surface ablation may not be well received by patients after a premium procedure. A new profile, in which the original cap is extended and opened like a LASIK flap, is being developed so that the re-treatment can be done on the stromal bed. – by Michela Cimberle
For more information:
Rupal Shah, MS, can be reached at New Vision Laser Centers, 303 Siddarth, R.C. Dutt Road, Vadodara, Gujarat 390007, India; +91-937-627-1000; email: rupal@newvisionindia.com.
Disclosure: Dr. Shah is a consultant for Carl Zeiss Meditec.