Vertical Gas Breakthrough During Corneal Flap Creation By Wavelight Fs200 Femtosecond Laser: A Consecutive Case Series

To report a cluster of consecutive cases of vertical gas breakthrough (VGB) during corneal flap creation by WaveLight FS200 femtosecond laser

Novyi Zir Clinic, Kyiv, Ukraine

This study included patients who underwent femtosecond-assisted LASIK using WaveLight FS200 femtosecond laser complicated by a vertical gas breakthrough during November 2023 – December 2023. Cases analysis included the next data: flap thickness (FT), bed laser pulse energy (BLPE), spot separation (SS), preoperative spherical equivalent (SEQ), surgical algorithm depending on depth of cavitation bubbles penetration related to the Bowman's membrane (BM) and relation to the optical zone (OZ), best corrected visual acuity (BCVA) preoperatively and 3 months after the procedure. The incidence of this complication during the 2 months and 2 months after changing flap thickness were recorded.

4 eyes (4 patients) were included to the study, with a mean follow-up of 2.25±0.96 months. In all 4 cases FT of 110 μm was programmed. BLPE was 0.80 mJ, with 8 μm SS. In all 4 cases preoperative BCVA was 0.00 LogMAR.  Mean preoperative SEQ was -5.75±1.06 D.  In 2 cases (50%) cavitation bubbles (CB) created buttonhole in the OZ followed by the abortion of ablation (1 case) and outside of the OZ followed by the ablation (1 case). In 2 cases (50%) CB stay under the BM, flap wasn’t lifted in 1 case and in 1 case ablation was performed. After 3 months post-op mean BCVA in 4 cases was 0.08±0.04 LogMAR. The incidence of this complication during the 2 months was 1.6% and 2 subsequent months after changing FT to 120 μm was 0% (p<0.01). 

Creation of a thicker flap could be an effective way to overcome technical malfunction of femtosecond laser to safely create thin corneal flaps. FINANCIAL DISCLOSURE: None