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Early trials show new excimer laser offers improved speed, eye tracking
Early results from a multicenter trial of the Amaris platform showed high accuracy and stable results in myopic and astigmatic eyes.
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STOCKHOLM — An excimer laser with a 500 Hz repetition rate and a multidimensional eye tracker has demonstrated the power of its new features in early results from a multicenter study, according to two ophthalmologists involved in the trials.
 Pavel Rozsíval |
Francesco Carones, MD, and Pavel Rozsíval, MD, spoke with Ocular Surgery News about their experience with the Schwind Amaris laser, which was recently launched at the European Society of Cataract and Refractive Surgeons meeting.
“This platform merges the sum of the technical requirements that us as surgeons would love to have in our excimer lasers,” Dr. Carones said in a telephone interview with OSN.
He performed laser treatments with the Amaris system on 61 eyes as part of the multicenter trial and said the results were “extremely good.”
Dr. Rozsíval operated on 105 eyes for the study and said although the system has a variety of new features, including surprising speed, there is no learning curve from other laser platforms.
“If [the surgeon] has already some experience with the excimer laser, there is almost no adaptation curve,” he said in a telephone interview.
Multicenter results
The prospective study was conducted at six sites and included 454 eyes that were treated for myopia or myopic astigmatism and followed for 1 month, according to information from Schwind.
The study included patients with maximum preoperative sphere of —9 D, maximum preop cylinder of —7 D and preop best corrected visual acuity of 20/25 or better. Monovision cases were excluded from the study.
The researchers measured uncorrected visual acuity, BCVA, topography and corneal and ocular wavefront using the Schwind Corneal and Ocular Wavefront Analyzer.
The mean patient age was 28 years and ranged from 18 to 60 years. The surgeons operated on 226 left eyes and 228 right eyes.
According to the 1-month results, spherical equivalent improved from a mean of —3.54 D at preop to –0.16 D postoperatively, sphere improved from a mean of —3.16 D preop to –0.05 D postop and cylinder improved from a mean of —0.75 D at preop to —0.24 D postop.
There was a high correlation between the laser settings for spherical equivalent and the achieved change. Additionally, the results showed that 74% of the eyes were within ±0.25 D of the attempted correction and 93% were within ±0.50 D of the intended correction at 1 month.
In terms of safety, the BCVA remained unchanged in 67% of the cases, 27% gained one line of BCVA, 4% gained two lines and 1% gained more than two lines. However, there was also a loss of one line of vision in 1% of cases, according to the data.
The results also showed that the results remained relatively stable from 1-day postop to the 1-month follow-up.
The surgeons concluded that they were able to achieve these results without additional nomograms but also said that further follow-up was necessary to properly evaluate the stability of the results.
Tracking eye movements
One of the key features of the Amaris platform is a 1,050 Hz turbo eyetracker that goes beyond the vertical and horizontal displacement and cyclotorsion compensations available with previous systems, according to Dr. Carones.
“It’s not just like displacing an eye in the X and Y position because when an eye moves, it also rolls, not only displaces, and the tracker is able to compensate for this rolling effect as well,” he said.
Dr. Carones refers to the lateral movement adjustments of previous models as first- and second-dimension displacements and refers to the rolling and cyclo-rotational movements the Amaris adjusts for as the third-, fourth- and fifth-dimension displacements.
The Amaris makes use of structures in the iris and sclera to recognize these movements and ensure that the ablation beam will always be in the correct position.
“If for any reason the pupil center shifts, like may happen during changes in illumination and so on, the tracker is not tricked by this because there is an unknown line of continuous compensation between the center of ablation, the center of the pupillary border and center of the limbus as well,” he said.
According to Dr. Carones, what these features mean is that the accuracy of ablations will be enhanced beyond what laser platforms can do already.
High-speed ablation
With a repetition rate of 500 Hz, the Amaris works quickly and can catch some surgeons off guard when they first use it, according to Drs. Rozsíval and Carones.
“The frequency of the laser … is very fast, so ablation for 1 D of myopia in 6 mm takes less than 3 seconds,” Dr. Rozsíval said.
Dr. Carones said this speed can be surprising at first and warned surgeons that wish to use the Amaris to be aware of the unusual speed.
“Don’t be scared about having a laser able to fire so fast because the first procedure will keep you saying ‘oh, my gosh, is it OK?’” he said.
For more information:
- Francesco Carones, MD, can be reached at Via Pietro Mascagni, 20, 20122 Milano, Italy; +39-02-7631-8174; fax: +39-02-7631-8506; e-mail: fcarones@carones.com.
- Pavel Rozsíval, MD, can be reached at the Ophthalmology Department, Charles University Teaching HO, Hradec Králové 500 05, Czech Republic; +42-49-55-14-582; fax: +42-49-55-14-582; e-mail: rozsival@lfhk.cuni.cz.
- Drs. Carones and Rozsíval have no direct financial interest in the products discussed in this article, nor are they paid consultants for any companies.
- Schwind eye-tech-solutions, maker of the Amaris system, can be reached at Mainparkstrasse 6-10, 63801 Kleinostheim, Germany; +49-6027-508-0; fax: +49-6027-508-208; Web site: www.eye-tech-solutions.com.
- Jared Schultz is an OSN Correspondent based in Philadelphia, U.S.A.