Densities of TUNEL-positive and DAPI-labelled cells, and total cell density (TUNEL+DAPI) were assessed. The control section was set to 30-μm depth from the untreated surface, while the lasered section was set to 30-μm depth from the lasered surface. Three-dimensional (3D) imaging from 2D z-stack images was reconstructed and viewed by using LAS X software (Leica). Using confocal laser scanning microscopy (SP8 Leica, Wetzlar, Germany), serial z-stack images (1-μm depth) of the central segment of lenticule were acquired. Subsequently, the lenticules were mounted with Fluoroshield containing 4′,6-diamidino-2-phenylindole (DAPI Santa Cruz Biotechnology, Santa Cruz, CA, USA). Fluorescence-based TUNEL assay was performed according to the manufacturer's instructions (Click-iT TUNEL Alexa-Fluor Imaging Assay Thermo Fisher Scientific, Waltham, MA, USA). Immediately after excimer laser ablation, the lenticules were fixed in 3% neutral buffered paraformaldehyde (Sigma-Aldrich) for 20 minutes and washed with PBS. 7 Lenticule implantation may also be useful to restore myopia in the nondominant eye of SMILE patients, to achieve monovision when reaching the presbyopic state. 18 One study of lenticule implantation for presbyopia has found increased uncorrected near vision acuity after implantation of a 1-mm lenticule button in the nondominant eye, trephined from a 2.50- to a 2.75–diopter (D) lenticule. 17 In patients with keratoconus and centrally positioned cones, implantation of centrally trephined lenticules caused a midperipheral steepening and consequently a central corneal flattening. 4, 5, 8, 17 In one case study of a previously complicated myopic laser-assisted in situ keratomileusis (LASIK) procedure, a SMILE-derived lenticule was successfully implanted under the corneal flap to reduce the amount of postoperative astigmatism. However, controlled lenticule dehydration before ablation is necessary in order to allow stromal thinning.įollowing the initial animal studies, clinical trials in lenticule implantation for patients with hyperopia have shown promising results with clear lenticules after surgery, although an undercorrection has been reported. 15.2 ± 5.5, P = 0.656) than the lasered group.Įxcimer laser ablation may be feasible for thinning and reshaping of SMILE-derived lenticules before reimplantation or allogenic transplantation. After implantation, the nonlasered group showed a tendency toward a greater increase in axial keratometry (6.63 ± 2.17 D vs. 233 ± 23 μm, P < 0.001) and after 5 hours in a moist chamber (46 ± 3 μm vs. The lasered porcine lenticules were thinner than the nonlasered controls during overhydration (132 ± 26 μm vs. SEM exhibited a more regular surface for the lasered lenticules, confirmed by the lower mean R z value (290.1 ± 96.1 nm vs. The collagen structure was also affected by the laser treatment but to a lesser extent. Corneal thickness and topography were assessed before and after implantation.įTIR illustrated prominent changes in the lipid profile. Ten SMILE-derived porcine lenticules, five nonlasered (107-μm thick, −6 diopter spherical power) and five excimer lasered (50% thickness reduction), were implanted into a 120-μm stromal pocket of 10 porcine eyes. The treatment effects in the lasered group were compared with the nonlasered group with respect to changes in surface functional groups (by Fourier transform infrared spectroscopy ) and surface morphology (by scanning electron microscopy and atomic force microscopy ). To evaluate the feasibility of excimer laser reshaping of biological lenticules available after small incision lenticule extraction (SMILE).įresh and cryopreserved SMILE-derived human lenticules underwent excimer laser ablation for stromal reshaping.
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