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ETIOLOGY AND INCIDENCE OF IRREGULAR FLAPS
Femtosecond LASIK
An irregular flap may happen after suction loss and a repeated flap cut attempt. Another risk factor for an irregular second pass is the disappearance of the transient opaque bubble layer before performing the second femtosecond pass. Irregular flap incidence with femtosecond LASIK is unknown.
Microkeratome LASIK
Irregular flaps (bileveled, bisected, or with a notch) may result from poor suction, damaged microkeratome blades, or irregular oscillation. Irregular flap incidence with microkeratome LASIK varies between 0.09% and 0.2%.1,2
Figure 9-1. Initial surgery resulted in an incomplete flap construction due to suction loss occurring at two-thirds the distance across the planned cut.
FEMTOSECOND LASIK COMPLICATIONS AND IMMEDIATE SOLUTIONS
Complication #1: Double Flap Due to Recut at Different Plane
Video section: 0 minutes 7 seconds
Platform: WaveLight FS200 (Alcon Labs)
Flap diameter: 9.1 mm
Flap target depth: 110 microns (µm)
The initial surgery on the right eye resulted in an incomplete flap construction due to suction loss occurring at one-third the distance across the planned cut. The second pass resulted in complete flap creation. Flap lifting revealed the presence of 2 different flaps that disrupted during dissection (video 9; time: 0 minutes 7 seconds; Figures 9-1, 9-2, 9-3, 9-4, 9-5, 9-6, and 9-7).
Some practical measures are as follows:
- Abort the surgery.
- Try to reconstruct the irregular flap before repositioning.
- Plan for a future surface refractive procedure.
Figure 9-2. Second pass resulted in complete flap creation.
Figure 9-3. Flap lifting revealed the presence of 2 different flap planes.
Figure 9-4. Several attempts were undertaken to reconstruct the irregular flap.
Figure 9-5. Flap was repositioned, and surgery was aborted. On the first day after surgery, the patient had a corrected distance visual acuity of 20/40 with a clear LASIK flap on slit lamp examination. At his 4-month follow-up visit, his corrected distance visual acuity was 20/25 with −2.50 −0.50 × 90 (see Figure 9-14). He underwent a surface refractive procedure with 40 seconds of mitomycin-C 0.02% 1 week later.
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