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Preliminary results of the first clinical trial with new femtosecond laser promising
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ATHENS — The Da Vinci femtosecond laser system produces highly precise LASIK flap cuts, with highly predictable thickness and smooth stromal bed surfaces, as shown by the first prospective clinical study with this new instrument, a presenter here said.
The Da Vinci femtosecond laser (Ziemer Ophthalmics) combines pulse energy in the low nanojoule range and frequency in the megahertz range with a high numerical aperture optic.
"This combination results in corneal resections of highly predictable quality," Bojan Pajic, MD, said at the ESCRS Winter Refractive Surgery Meeting.
"The surgical procedure is very fast and easy, with no resistance to flap separation and a cutting time of 20 to 25 seconds, nearly as fast as the mechanical keratome," Dr. Pajic said. "Small bubbles in the cutting interface disappear immediately after flap lifting, and no opaque bubble layer was observed in the eyes we treated."
According to Dr. Pajic, the LASIK flaps of the first 20 eyes underwent clinical evaluation and were analyzed using topography, wavefront measurement, corneal OCT and confocal corneal laser-scanning microscopy. The flaps were also compared with an equal number of flaps performed with the Amadeus SIS mechanical keratome. The intended flap thickness was 140 µm in all cases.
"The [Da Vinci] produced smoother interfaces and showed no tissue bridges. Confocal microscopy showed very little edema compared with the SIS keratome. The mean flap thickness was 141 µm with a standard deviation of 8.5 µm. The Amadeus produced slightly thicker flaps, with a mean thickness of 143 µm and a standard deviation of 21.7 µm," Dr. Pajic said.
A comparison also was made with IntraLase FS laser flaps (IntraLase), which were equally predictable and had a similarly small standard deviation.
Visual acuity restored significantly faster in the eyes treated with femtosecond laser than in those treated with the mechanical keratome.
At present, the Da Vinci system can only be used for cutting standard LASIK flaps, but soon it will be updated for use with other types of corneal surgery.