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Microkeratome, femtosecond laser have similar impact on corneal biomechanics in flap creation
VIENNA, Austria — Microkeratome vs. femtosecond laser flap creation modalities have an equal impact on corneal biomechanics, according to a study.
The Ocular Response Analyzer (Reichert) was used to measure corneal hysteresis, "a critical parameter regarding the viscoelastic properties of the cornea," according to Marlene Kroher, MD, speaking at the European Society of Cataract and Refractive Surgeons meeting.
The comparison was made between a group of 28 eyes treated with a mechanical microkeratome (Amadeus II, Ziemer Ophthalmics) and a group of 59 eyes treated with a femtosecond laser (VisuMax, Carl Zeiss Meditec) for flap creation, followed by excimer laser treatment for myopic astigmatism. Intended flap thickness of 120 µm and optical zone of 6.5 mm were identical in both groups.
Corneal hysteresis was measured before and 3 months after LASIK. A decrease from 10.79 mm Hg to 9.31 mm Hg was reported after LASIK in the microkeratome group, with a mean ablation depth of 68.71 µm. In the femtosecond laser group, the decrease was from 10.52 mm Hg to 8.62 mm Hg with an ablation depth of 88.64 µm.
"There is a significant correlation between ablation depth and corneal hysteresis, but not between hysteresis and flap creation," Dr. Kroher said. "Therefore, the advantage of using femtosecond laser over mechanical microkeratome has to be discussed critically."
- Disclosures: Dr. Kroher has no relevant financial disclosures..