Abstract
Purpose. To evaluate the change in intraocular pressure (IOP), central corneal thickness (CCT), axial length, peripapillary retinal nerve fiber layer (RNFL) thickness, and macular ganglion cell complex (GCC) thickness after small incision lenticule extraction (SMILE) surgery. Methods. This prospective observational study was conducted in Espace Nouvelle Vision, Ophthalmological Clinic, Paris, France. Fifty eyes of 25 patients were enrolled in this study and underwent SMILE surgeries. IOP, central corneal thickness (CCT), axial length (AL), peripapillary RNFL thickness, and macular GCC thickness were measured before and at 3 months after SMILE. Results. The mean preoperative spherical equivalent was −3.15 ± 1.50 diopters (D), and the mean postoperative value was 0.15 ± 0.28 D. After SMILE surgery, IOP decreased from 15.03 ± 2.79 mmHg to 11.02 ± 2.73 mmHg and 10.02 ± 2.21 mmHg at 1 and 3 months, respectively ( P < 0.01 for both comparisons). The mean decrease in measured IOP as a function of ablation depth was 0.065 ± 0.031 mmHg/μm. CCT decreased from 545.98 ± 26.61 μm to 478.40 ± 30.26 μm after SMILE surgery ( P < 0.01 ). AL decreased from 24.80 ± 0.84 mm to 24.70 ± 0.83 mm ( P < 0.01 ). There was no statistically significant change in mean peripapillary RNFL or mean GCC thickness after SMILE surgery. Conclusions. SMILE surgery modified IOP measurement, CCT, and AL but did not change peripapillary RNFL and macular GCC thicknesses. The postoperative drop in measured IOP might be explained by the decreased CCT. An accurate re-evaluation of AL should be performed before cataract surgery among post-SMILE patients.
Highlights
Small incision lenticule extraction (SMILE) is a novel form of refractive surgery for the treatment of myopia and myopic astigmatism
axial length (AL) decreased from 24.80 ± 0.84 mm to 24.70 ± 0.83 mm (P < 0.01). ere was no statistically significant change in mean peripapillary retinal nerve fiber layer (RNFL) or mean ganglion cell complex (GCC) thickness after small incision lenticule extraction (SMILE) surgery
central corneal thickness (CCT) decreased from 545.98 ± 26.61 μm to 478.40 ± 30.26 μm 3 months after SMILE surgery (P < 0.01)
Summary
Small incision lenticule extraction (SMILE) is a novel form of refractive surgery for the treatment of myopia and myopic astigmatism. Intraocular pressure (IOP) has been reported to increase during both FS-LASIK [5, 6] and SMILE refractive surgeries [7, 8]. Intraoperative and postoperative complications such as macular hole [9] and retinal detachment [10] related to the sudden increase in IOP have been reported in FS-LASIK patients. During the SMILE procedure, a curved lens is applied to the edge of the cornea and limbus, and the suction pressure generated by the VisuMax laser system is lower than in FS-LASIK, approximately 35 mmHg [14]; SMILE should not induce complications related to a sudden increase in IOP, as the pressure is low enough to maintain the intraocular circulation. The FLEx procedure takes significantly more time (25–28 seconds) than FS-LASIK; eyes undergoing FLEx are exposed to a longer duration of increased IOP [8]
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