Outcomes Of New Femtosecond Laser-Assisted Flap Creation For Lasik Retreatment

To report the safety and efficacy of new femtosecond laser-assisted flap creation for retreatment following LASIK.

Single centre, single surgeon, private practice, London, UK. 

18 eyes of 13 patients previously treated with LASIK were retreated with a new femtosecond laser flap. The Ziemer Femto LDV Z8 was used for flap creation and Schwind Amaris 1050RS for excimer ablation. Central and peripheral original LASIK flap depth was measured using anterior segment optical coherence tomography. Flaps with an original depth of ≥130µm had a new 100µm or 110µm femtosecond flap created, and 100-110µm flaps were treated with a 140-145µm femtosecond flap to allow a minimum inter-flap stromal depth of 30µm. The diameter of the flap was 9 or 9.5mm. Hinge location was superior and unchanged from the original LASIK flap. Uncorrected and corrected visual acuities, refractive outcomes and complications were reported at 3 months.

7 males and 6 females with mean age of 53 years were treated. Mean duration from primary LASIK was 11 years (range 4 months – 20 years). 11 eyes were targeted for emmetropia and 7 for myopia to address presbyopia. Mean post-operative corrected distance visual acuity was -0.11 ±0.05 LogMAR. Emmetropic aim eyes (n=11) achieved a mean uncorrected distance visual acuity of -0.1 ±0.07 LogMAR. Myopic aim eyes (n=7) achieved a mean uncorrected near visual acuity of -0.05 ±0.09 LogMAR. One eye lost one line of best corrected vision. 83.3% achieved post-operative spherical equivalent refraction within 0.25 D of target and 100% within 0.5 D. One eye required trimming of an inferior thin sliver of stromal tissue with bandage contact lens placement.

This study demonstrates that new femtosecond laser-assisted flap creation may be a feasible alternative to late flap lift and surface ablation in prior LASIK cases requiring retreatment. Visual and refractive outcomes were excellent with no visually significant complications. The literature reports creation of new femto-assisted side cuts or the creation of a ‘mini-flap’ 7mm in diameter. However, there is to our knowledge no outcomes of standard diameter newly created femto-assisted LASIK flaps for retreatment reported. Although risks involving loss of slivers of tissue remain, advances in femtosecond laser technology and precision of cuts as well as ease of resection have made this technique more achievable in experienced hands.