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D. T. Tan, J. S. Mehta, M. Nubile, L. H. Yuen, L. Mastropasqua, R. W. Beuerman; Suction Loss During Femtosecond Laser Ablation for LASIK Flaps. Invest. Ophthalmol. Vis. Sci. 2009;50(13):595.
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© ARVO (1962-2015); The Authors (2016-present)
Femtosecond lasers have been shown to produce high quality and reproducible lamellar flaps for LASIK. In order to produce adequate fixation, many lasers use a coupling device for the patient interface. Newer femtosecond lasers have incorporated the suction into the patient interface to improve patient comfort and allow low-pressure laser ablation. The aim of this study was to examine the causes and effect of suction break during laser ablation.
Prospective clinical cases series of 50 consecutive cases of lamellar LASIK flaps produced by a Visumax (Carl Zeiss Meditec, Jena, Germany) femtosecond laser. Parameters examined were interface cone size, energy used, diameter of ablation, age of patient and corneal diameter (white to white(WTW)) from IOL master or Orbscan. Eye bank study on 12 human cornea-scleral rims. Suction breaks were induced during ablation. Following re-alignment of fixation the lamellar bed was re-ablated using the same power and depth setting. Flaps were lifted (n=5) and processed for light microscopy, scanning electron microscopy and histology.
Suction breaks occurred in 2 of 50 cases. Both cases occurred with the use of the Medium size interface cone. This was chosen on the basis of the WTW reading from the IOL master. The mean difference between Orbscan and IOL master reading of WTW was 0.7 (0.26)mm. There was no correlation between energy used, diameter of ablation, age of patient and suction break. Histology sections showed that following re-fixation the laser was able to ablate at the same lamellar depth as before suction loss. Qualitatively there was no difference in smoothness of the lamellar bed in corneas that underwent suction break and control corneas.
Orbscan measurements of WTW provide more accurate diameters for choosing of interface cones for the Visumax laser in Asian eyes than IOL master. Following a suction break the laser accurately realigned to the pre-programmed lamellar ablation depth without any loss in quality of the lamellar interface.
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