Femtosecond (FS) laser vision correction procedure for moderate to high myopia: a prospective study of ReLEx^® flex and comparison with a retrospective study of FS‐laser in situ keratomileusis

Abstract

ABSTRACT.Purpose: To present our initial clinical experience with ReLEx Ò flex (ReLEx) for moderate to high myopia. We compare efficacy, safety and corneal higher-order aberrations after ReLEx with femtosecond laser in situ keratomileusis (FS-LASIK). Methods: Prospective study of ReLEx compared with a retrospective study of FS-LASIK. ReLEx is a new keratorefractive procedure, where a stromal lenticule is cut by a femtosecond laser and manually extracted. Forty patients were treated with ReLEx on both eyes. A comparable group of 41 FS-LASIK patients were retrospectively identified. Visual acuity, spherical equivalent (SE) and corneal tomography were measured before and 3 months after surgery. Results: Preoperative SE averaged )7.50 ± 1.16 D (ReLEx) and )7.32 ± 1.09 D (FS-LASIK). For all eyes, mean corrected distance visual acuity remained unchanged in both groups. For eyes with emmetropia as target refraction, 41% of ReLEx and 61% of FS-LASIK eyes had an uncorrected distance visual acuity of logMAR £ 0.10 at day 1 after surgery, increasing to, respectively, 88% and 69% at 3 months. Mean SE was )0.06 ± 0.35 D 3 months after ReLEx and )0.53 ± 0.60 D after FS-LASIK. The proportion of eyes within ±1.00 D after 3 months was 100% (ReLEx) and 85% (FS-LASIK). For a 6.0-mm pupil, corneal spherical aberrations increased significantly less in ReLEx than FS-LASIK eyes. Conclusions: ReLEx is an all-in-one femtosecond laser refractive procedure, and in this study, results were comparable to FS-LASIK. Refractive predictability and corneal aberrations at 3 months seemed better than or equal to FS-LASIK, whereas visual recovery after ReLEx was slower.

Comparison of Visual and Refractive Outcomes Following Femtosecond Laser-Assisted LASIK With SMILE in Patients With Myopia or Myopic Astigmatism

“…9 In a comparative study between SMILE and FS-LASIK, Vestergaard et al found that CDVA was better than 20/20 in 85% of eyes in the SMILE group and in 83% of eyes in the LASIK group postoperatively. 10 However, in a comparative study between SMILE and FS-LASIK, Lin et al found no significant difference between eyes attaining a UCVA of 20/20 in the two groups. 11 Hu et al found 48 eyes in the SMILE group and 37 eyes in the LASIK group showing a gain of one line.…”

New Developments in the Lenticule Extraction Procedure

“…4 Another study on 54 eyes found no regression during the first 6 months after surgery. 8 Similarly, no regression has been found during the first 3-6 months after 500 kHz FLEx 10,11,13,14 or for 1 year after 200 kHz FLEx. 15,16 A prospective, randomised, paired-eye study comparing SMILE and FLEx documented no significant regression between 1 week and 6 months.…”

“…ingrowth and monocular ghost images. 10,11,19 Recently, we found irregular postoperative topography in 18 of 1,574 eyes, giving rise to ghost images in six cases. 23 Topography-guided PRK was performed in four of these eyes, ameliorating the symptoms in three cases.…”

“…2,3,[8][9][10][11][12][13][14] In one study on 279 eyes after SMILE, 0.4 % of eyes were reported to have a loss of two or more lines. 3 By contrast, a 2.4 % risk for a two-line loss was found in 670 eyes by Hjortdal et al 6 However, in the same study, a safety index (CDVA before/CDVA after surgery) of 1.07±0.22 was found, indicating that CDVA on average increased after surgery, as would be expected because of the image magnification of myopic keratorefractive procedures.…”

Surgical instruments for small incision lenticule extraction (SMILE)

“…This might be due to: (i) suboptimal laser photo-disruption of the stromal fibers that subsequently causes interface scattering due to traumatic dissection [9] -this can be rectified by optimization of the laser settings, (ii) micro-distortions in Bowman's layer following lenticule removal [10], and (iii) transient increased stromal keratocyte activity at the interface resulting from the stromal pocket irrigation [11]. Hence, smooth, atraumatic dissection, of the stromal lenticule and sweeping of the anterior cap both to disperse the microdistortions to the periphery, and also to aid in drainage of the pocket fluid, can enhance the postoperative visual recovery.…”