Small incision lenticule extraction (SMILE) in the correction of myopic astigmatism: outcomes and limitations - an update

Abstract

Small Incision Lenticule Extraction (SMILE) is a flap-free intrastromal technique for the correction of myopia and myopic astigmatism. To date, this technique lacks automated centration and cyclotorsion control, so several concerns have been raised regarding its capability to correct moderate or high levels of astigmatism. The objective of this paper is to review the reported SMILE outcomes for the correction of myopic astigmatism associated with a cylinder over 0.75 D, and its comparison with the outcomes reported with the excimer laser-based corneal refractive surgery techniques. A total of five studies clearly reporting SMILE astigmatic outcomes were identified. SMILE shows acceptable outcomes for the correction of myopic astigmatism, although a general agreement exists about the superiority of the excimer laser-based techniques for low to moderate levels of astigmatism. Manual correction of the static cyclotorsion should be adopted for any SMILE astigmatic correction over 0.75 D.

Influence of Preoperative Astigmatism Type and Magnitude on the Effectiveness of SMILE Correction

“…[7][8][9] However, there is still some controversy when it comes to treating astigmatism with SMILE. 10 Some patients who have SMILE may have a resultant refractive error, induced astigmatism, or regression. 10,11 If their resultant refractive error is significant enough, these patients may seek further refractive correction or enhancement.…”

“…10 Some patients who have SMILE may have a resultant refractive error, induced astigmatism, or regression. 10,11 If their resultant refractive error is significant enough, these patients may seek further refractive correction or enhancement. Re-treatment rates after SMILE have not been extensively reported, but Re-instein et al 12 reported a 4% enhancement rate after low myopic treatment (spherical equivalent [SE] up to -3.50 diopters [D] and cylinder up to 1.50 D).…”

Two-Year Outcomes After Full-Thickness Astigmatic Keratotomy Combined with Small-Incision Lenticule Extraction for High Astigmatism

“…13,20−23 Several adjustments of current treatment nomograms have been suggested, leading to a 10% increment in the magnitude of astigmatism correction. 4,24 Currently, however, there are no standardized nomograms for astigmatism correction.…”

Corneal refractive surgery combined with simultaneous corneal cross‐linking: Indications, protocols and clinical outcomes—A review

“…[1][2][3][4][5][6] However, despite advancements in femtosecond and excimer lasers, refractive corrective surgeries have a definite impact on the biomechanical properties of cornea. [1][2][3][4][5][6] However, despite advancements in femtosecond and excimer lasers, refractive corrective surgeries have a definite impact on the biomechanical properties of cornea.…”

“…Corneal refractive surgery is performed worldwide for correction of myopia, myopic astigmatism and hyperopia. [1][2][3][4][5][6] However, despite advancements in femtosecond and excimer lasers, refractive corrective surgeries have a definite impact on the biomechanical properties of cornea. [7][8][9][10] The creation of a flap in laser in situ keratomileusis (LASIK) plus ablation with excimer laser, removal of a lenticule from corneal stroma in small incision lenticule extraction (SMILE), and ablation of Bowman's layer in photorefractive keratectomy (PRK), all lead to weakening of anterior stroma and decrease in corneal stiffness.…”