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New-generation excimer laser provides high-quality vision, minimal thermal strain
The laser may be ideal for surface ablation because it minimizes haze formation.
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A new-generation excimer laser provides good visual outcomes through fast, precise treatment with minimal thermal strain to the cornea, according to one surgeon.
The 500 Hz Microscan laser platform (Nanovision Group), manufactured in Russia and recently launched on the European market, is the latest evolution of the original 20 Hz prototype developed by Fyodorov and Prokhorov in 1986. The machine has been progressively upgraded to 100 Hz and 300 Hz. The new 500 Hz laser provides enhanced features for wavefront-guided customized treatments.
“The laser is linked to the L-80 Wave+ Visionix-Luneau aberrometry-topography system and has an incorporated eye tracker with pupil and iris registration. It enables extremely accurate, customized ablation programs for all types of refractive error, with large optical zones up to 9 mm, using both LASIK and surface techniques,” Dimitrii Dementiev, MD, said in an interview with Ocular Surgery News.
Dementiev, who practices in Russia and Italy, uses different excimer lasers in the two locations but said he is obtaining the best results with the new machine.
“I did not believe in super-vision before I tried this laser, but the reality now is that nearly 60% of my patients achieve 20/10,” he said.
Study results
In a study, 134 eyes of 70 myopic patients were included. Mean patient age was 31 years, ranging between 18 years and 64 years. Preoperative myopia ranged from 2.5 D to 7 D, and astigmatism ranged from 0 D to 3.75 D.
“The laser potentially allows a much broader range of correction, up to –14 D with LASIK and –20 D with PRK, but I prefer not to stretch so far to avoid poor optical quality,” Dementiev said.
Pupil size in mesopic conditions varied between 5 mm and 7.4 mm, and optical zone size was planned accordingly, varying between 7 mm and 8.3 mm. LASIK was performed in all eyes.
“We have 18 months of follow-up now. The mean preoperative BCVA was 20/30, and we achieved 20/20 or better in 93% of the eyes and 20/10 in 58% of the eyes without spectacle correction. At least one line of BCVA was gained by 47% of the eyes, and no eye lost BCVA lines. The improvement was statistically significant due to the minimum induction of aberration,” Dementiev said.
Predictability was high, with 96% of the eyes within 0.5 D of intended correction. The wavefront-guided treatment allowed reduction of spherical equivalent from a mean of –3.35 D to 0.043 D. Mean cylinder was reduced from –0.9 D to 0.26 D.
A Moria microkeratome was used to perform thin 90-µm flaps.
“We’ve just completed a platform integrating a femtosecond laser, but we are very happy with the Moria microkeratome as well and will probably be using both,” Dementiev said.
High patient satisfaction
“The ‘wow’ effect is relatively common in the laser correction, so I did not expect that it could be so much better with the wavefront-guided treatment. The quality of vision was so high and the patients so much happier immediately after surgery. Visual rehabilitation was also faster than it used to be with conventional ablation,” Dementiev said.
The high repetition rate of the laser reduced ablation time significantly. A treatment that is over in just a few seconds greatly increases patient comfort and takes away a lot of anxiety, he said.
No inflammatory or other laser-related reactions were seen after the treatment. A fingernail injury of the flap was reported, but no flap repositioning was needed. Microbial keratitis developed in both eyes of one patient 1 week after surgery and was successfully treated with antibiotics.
A second study of PRK vs. LASIK is ongoing. Despite the high power used, the Microscan laser produced a minimal temperature increase in the cornea and minimal haze.
“We had no haze in the eyes treated so far. Maybe this laser is what was needed to overcome the drawbacks of surface ablation. PRK, which has been shown to have significant advantages in the long term, might have a chance to become the procedure of choice with a laser that does not heat the cornea and prevents haze formation. This might be the next evolution of refractive laser correction,” Dementiev said.
Three of the latest 500 Hz generation machines are currently operating in Russia, while the previous 300 Hz system is used in 36 centers. A CE mark was received in April, and the laser is ready for the European market. The first four centers in Europe have been contacted to set up a multicenter European reference study, including Ioannis G. Pallikaris, MD, in Greece, Jorge L. Alió, MD, PhD, in Spain, Matteo Piovella, MD, in Italy and François Malecaze, MD, in France, Dementiev said. – by Michela Cimberle
- Reference:
- Dimitrii Dementiev, MD, chief medical investigator for Nanovision Group, can be reached at International Center for Ophthalmology, Davidkovskaja street 3/2, Moscow, Russia; +74959389779 or +393356025665; email: eye3d@mail.ru.
Disclosure: Dementiev’s research is partially funded by OptoSystems.