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Comparison of an incidence of an opaque bubble layer and impact on visual outcomes using two types of femtosecond lasers

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Session Details

Session Title: Presented Poster Session: Keratorefractive Results I

Venue: Poster Village: Pod 2

First Author: : J.Ventruba CZECH REPUBLIC

Co Author(s): :    R. Anderle   V. Kalandrova           

Abstract Details


To assess the incidence of an opaque bubble layer (OBL) and impact on visual acuity using VisuMax 500kHz femtosecond laser (Zeiss) and Femto LDV Z6 (Ziemer) during laser in situ keratomileusis (LASIK).


European Eye Clinic Lexum, Czech Republic, Optegra Eye Sciences


Study of 188 eyes, who underwent LASIK, were divided in 2 groups – LDV group (48 eyes) and VisuMax group (140 eyes). Preoperative and postoperative tests included uncorrected visual acuity (UDVA), corrected visual acuity (CDVA) and manifest refraction (MR). Main outcomes were checked at postoperative 1 day and 2 months. Screen captures were obtained after the flap creations and then analysed. Presence of OBL was classified as 0 (no evidence of OBL), 1 (OBL outside the central optical zone) and 2 (OBL invading the central zone). OBL area as a percentage of the corneal flap area, was measured.


Preoperatively, there was no difference between groups. The incidence rate of OBL in LDV group was 0% (0 eyes), in VisuMax group (35,7%, 50 eyes). In VisuMax group, the mean OBL area was 9,6% (range: 0%-25,2%). Postoperative comparison of the LDV group and the VisuMax OBL group revealed statistically significant better outcomes in the LDV group in 1 day UDVA (1,05 vs 0,99, p=0,04) and 2 months UDVA (1,23 vs 1,17, p=0,03). Presence of the OBL was correlated with worse 1 day UDVA (p=0,01) and the percentage of the OBL area with worse 2 month UDVA (p=0,04) and CDVA (p=0,03).


Both femtosecond lasers have shown very good efficacy and safety for the creation of corneal flaps. No eye required postoperative surgical intervention. However, Femto LDV Z6 had no evidence of OBL and slightly better visual outcomes than VisuMax.

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