DEEP FLAP (>120 ΜM) LASIK: INTRAOPERATIVE FINDINGS, POST-OPERATIVE COURSE AND IMPLICATIONS FOR FLAP THICKNESS SAFETY

To report a case of femtosecond-created LASIK flap depth >120 µm in a myopic patient, describing intraoperative management, postoperative outcomes, and discussing the implications of deep flap creation on residual stromal bed, biomechanics and complication risk.

Single-centre refractive surgery unit in Cologne, Germany

A 28-year-old male with myopia -6.50 D and astigmatism -1.25 D underwent LASIK using femtosecond flap creation. The planned flap thickness was 100 µm but intraoperative pachymetry and flap-lift OCT indicated an actual flap thickness of 125 µm. The ablation profile was adjusted accordingly. Pre- and post-operative metrics included uncorrected distance visual acuity (UDVA), best-corrected visual acuity (BCVA), corneal tomography (thickness, residual stromal bed), flap edge inspection, interface clarity, and slit-lamp findings at day 1, week 1, month 1 and month 6.

Intraoperative confirmation of flap thickness at 125 µm left a residual stromal bed of 295 µm (pre-operative central thickness 420 µm). UDVA was 20/20 at 1 month and maintained at 6 months. No signs of ectasia or flap-related complications (e.g., flap dislocation, striae, epithelial ingrowth) were observed. Corneal tomography at 6 months showed stable keratometry and no posterior elevation. The flap-bed interface was clear. The deeper flap did not negatively impact visual outcome in this case, but highlights need for intraoperative verification of flap parameters and caution when residual stromal bed margin is reduced.

Although outcomes were favourable, a flap thickness exceeding 120 µm may reduce safe residual stromal bed margin and theoretically increase biomechanical risk. This case underscores the importance of accurate flap creation, intraoperative measurement, and tailoring ablation when flap depth deviates from plan. Surgeons should consider deeper flap thickness as a variable in refractive surgery risk assessment and counselling.