Visual Quality Similar After SMILE, LASEK for Patients With Low Myopia

Both small incision lenticule extraction and laser-assisted subepithelial keratomileusis yield stable long‑term visual quality improvements in low myopia.

Both small incision lenticule extraction (SMILE) and laser-assisted subepithelial keratomileusis (LASEK) yield stable, long‑term improvements in vision for patients who underwent the procedures for low-myopia correction, according to research published in BMC Ophthalmology.

Investigators conducted a prospective study to compare visual quality and corneal wavefront aberrations following SMILE and LASEK for c correction between June 2018 and January 2019.

The team assessed 2-year visual outcomes and objective and subjective measures visual quality, including uncorrected and corrected distance visual acuity (UDVA and CDVA), manifest refraction, and corneal wavefront aberrations.

A total of 29 eyes of 29 patients who underwent SMILE (mean age, 26.79 years; range, 21-40 years; 72% men, 28% women) and 23 eyes of 23 patients who received LASEK (mean age, 29.34 years; range, 20-40 years; 48% men, 52% women) participated in the study.

The researchers report a 2-year efficacy index (postoperative UDVA/preoperative CDVA) of 1.19±0.17 in the SMILE group and 1.23±0.20 in the LASEK group (P =.42). They found that no eyes lost more than 2 lines of CDVA and that 93% of eyes in the SMILE group and 91% of eyes in the LASEK group had spherical equivalent within ±0.25 diopters (D). 

The team observed that postoperative increases in the total corneal spherical aberration and the corneal front spherical aberration were lower in the SMILE group than in the LASEK group (P <.01, for both). They also found that the increases in the total corneal vertical coma and the corneal front vertical coma in the SMILE group were greater than those in the LASEK group (P <.01, for both). 

Compared with SMILE, less corneal tissue is removed in LASEK, and therefore it is more suitable for patients with relatively thin cornea.

The researchers reported that all procedures during the study period were uneventful.

“In addition to safety and efficacy, other considerations also should be considered when selecting surgical methods for patients,” researchers explain. SMILE and LASEK have their own advantages and disadvantages. For example, SMILE maintains the integrity of the corneal epithelium and Bowman’s layer and is free of fap-related complications; however, it requires 10 to 30 μm of additional base thickness in the corneal stroma, and thus more corneal tissue is removed using this technique. “LASEK is also a fapless procedure, which prevents fap-related complications. Compared with SMILE, less corneal tissue is removed in LASEK, and therefore it is more suitable for patients with relatively thin cornea.”

Limitations of the study included lack of analysis of the effect of total ocular aberrations on visual quality, inclusion of only patients with spherical equal to -3.00 D or less and astigmatism equal to 1.50 D or less, and the relatively small sample size.

References:

Fu M, Li M, Wei R, Zhang C, Huang Y, Niu L, Wang X, Zhang H, Zhou X. Long-term visual quality after small incision lenticule extraction (SMILE) and laser assisted subepithelial keratomileusis (LASEK) for low myopia. BMC Ophthalmol. 2022;22(1):347. doi:10.1186/s12886-022-02568-8