Posters

Evaluation of aberrometric and topographic changes after refractive surgery using the SMILE technique

Poster Details

First Author: P.Tañá SPAIN

Co Author(s):    J. Belmonte   J. Rodríguez-Prats   J. Muñoz   C. Tello     

Abstract Details

Purpose:

The SMILE (Small Incision Lenticule Extraction) is a variation of the ReLEx (Refractive Lenticule Extraction) technique that allows surgical correction of myopia without requiring a flap to be lifted for extracting the lenticule. The aim of this study was to evaluate short-term topographic and aberrometric changes in the anterior corneal surface of patients undergoing SMILE.

Setting:

Oftalvist Ophthalmology Clinic, Oftalvist Group, Alicante, Spain.

Methods:

Seventy-eight (78) patients, 33 men and 45 women with a mean age of 31.87 ± 7.04 years (157 eyes) underwent SMILE refractive surgery between October 2012 and December 2013. The study was performed in accordance with the guidelines of the Declaration of Helsinki. All subjects were over 18 years of age and signed informed consent. All patients were treated according to the same surgical protocol. The following parameters were defined: flap thickness, 120 or 130 µm; optic zone diameter, 6.5 mm; and flap diameter 7.5 mm. All incisions, between 2 and 4 mm, were made at 110-120°. Flat, steep and mean keratometric radii, asphericity, 4th order spherical aberration, horizontal and vertical coma and trefoil were evaluated before surgery and one month after the procedure. Keratometric and aberrometric parameters were also correlated with refractive changes and visual acuity after surgery.

Results:

The spherical equivalent before surgery was −4.52 ± 1.96 diopters, falling to −0.22 ± 0.48 diopters after the procedure. Mean uncorrected distance visual acuity post-surgery (UDCVA) was −0.03 ± 0.11 LogMAR. 90.4% achieved UDCVA of at least 0.1 LogMAR (0.8 decimal). 88% showed no refraction one month after surgery and 96.5% had postoperative refraction of ≤0.50 D. Mean asphericity was −0.26 ± 0.19 before surgery and 0.19 ± 0.29 after surgery. Statistically significant differences were found for steep K, flat K, mean K, asphericity, spherical aberration and vertical coma (p < 0.005). On the other hand, no significant differences were found in the Root Mean Square (RMS) for higher order aberrations, horizontal coma or trefoil. Postoperative asphericity correlated strongly with 4th order spherical aberration and vertical coma. Six eyes developed intraoperative complications (confusion between the anterior and posterior planes with stromal damage, loss of suction during the creation of the anterior surface of the lenticule and decentering when creating the lenticule) and five eyes developed complications after surgery (haze, diffuse lamellar keratitis and self-limiting epithelial growth).

Conclusions:

Significant changes in the topographic parameters of the anterior corneal surface, spherical aberration and vertical coma were found after SMILE surgery. However, higher order RMS was not affected. In addition, the SMILE technique seems to be effective and predictable with a high degree of success in terms of refraction and uncorrected visual acuity one month after surgery. FINANCIAL INTEREST: NONE