Comparative study of wave-front aberration and corneal Asphericity after SMILE and LASEK for myopia: a short and long term study

Abstract

Background The study compares the wave-front aberration and corneal asphericity from multiple perspectives after Small Incision Lenticule Extraction and Laser-assisted Subepithelial Keratomileusis for mild to moderate myopia in a short and long time period. Methods This prospective and comparative study included 32 eyes in the SMILE group, with a mean spherical equivalent (SE) of − 4.1 ± 0.9D and 32 eyes in the LASEK group, with a mean SE of − 3.7 ± 1.0D. Visual acuity, refractive error, wave-front aberration, corneal Q value and corneal refractive power were analyzed pre-, 3 months and 3 years post-operatively. Results There was no significant difference in refractive error, wave-front aberration, corneal Q value and corneal refractive power before treatment. Three months postoperative, Q value within 6 mm (SMILE: 0.46 ± 0.27, LASEK: 0.63 ± 0.28, p = 0.02), the relative peripheral corneal power (5-8 mm: p < 0.05), change of higher order aberration (SMILE: 0.10 ± 0.16, LASEK: 0.24 ± 0.20, p = 0.004) and spherical aberration (SA, SMILE: -0.07 ± 0.30, LASEK: -0.41 ± 0.40, p < 0.001) were significantly lower in the SMILE than in LASEK group. The visual acuity, refractive error, coma, peripheral Q value, central corneal power had no significant difference between the two groups. Three years post-operation, the corneal power distribution results and SA were similar to that of 3-month, while the Q value had no significant difference between the two groups. Conclusion In the early stage after SMILE, the HOAs was lower, the corneal refractive power from central to periphery was more uniform than after LASEK; and in the long-term run, SMILE still preceded LASEK in the corneal asphericity and aberration. Electronic supplementary material The online version of this article (10.1186/s12886-019-1084-3) contains supplementary material, which is available to authorized users.

Corneal asphericity and related factors in the geriatric population: A population‐based study

“…This list includes studies that primarily aimed to investigate the distribution of the Q value or its associated factors. Others only evaluated Q value changes after a therapeutic intervention (mainly refractive surgery) that were not included in this table due to their small sample size 12,38‐42 . As shown in Table 6 , reported values of the mean anterior Q value cover a wide range from −0.03 to −0.44.…”

“…4,8 Accordingly, even a small change in the corneal shape can be associated with a significant reduction in image quality. 9 Awareness of corneal asphericity is critical to understanding the overall shape of the cornea and is important for a variety of clinical purposes, including contact lens fitting, 10 measurement of ocular aberrations, 11 refractive surgery, 12,13 diagnosis of corneal pathology 14 and intraocular lens implantation. 15,16 Today, with aspheric intraocular lenses, the goal of cataract surgery has changed from merely restoring visual acuity to achieving superior postoperative function (including restoring contrast sensitivity and improving retinal image quality under different illuminations, including daylight, mesopic, and scotopic conditions).…”

Clinical Outcomes of Small Incision Lenticule Extraction in Myopia: Study of Vector Parameters and Corneal Aberrations

“…Postoperative coma can increase with decentration [21]. Studies have suggested that mild decentration without a tracking system may induce a smaller increase in coma [18,22]. We tried to minimize decentration using the triple centration technique [7].…”

Astigmatism Correction Using SMILE

“…This could be because of its more uniform corneal refractive power, leading to fewer changes in corneal higher order aberrations. 6 Last year, SMILE was approved by the FDA for the treatment of myopic astigmatism up to 3.00 D. However, astigmatism correction remains a challenge in SMILE, especially for surgeons new to the technique. The purpose of this review is to discuss the factors that affect astigmatism correction in SMILE and to discuss techniques to improve refractive outcomes.…”