Relationship Between Decentration and Induced Corneal Higher-Order Aberrations Following Small-Incision Lenticule Extraction Procedure

Abstract

Citation: Lee H, Roberts CJ, ArbaMosquera S, Kang DSY, Reinstein DZ, Kim T. Relationship between decentration and induced corneal higherorder aberrations following small-incision lenticule extraction procedure. Invest Ophthalmol Vis Sci. 2018;59:2316-2324. https://doi.org/ 10.1167/iovs.17-23451 PURPOSE. To investigate the amount of lenticule decentration following small-incision lenticule extraction (SMILE) by using the Keratron Scout tangential topography difference map, and the relationship between the magnitudes of total decentration and induced corneal higher-order aberrations (HOAs).METHODS. This retrospective observational case series study analyzed decentration values obtained from the Keratron Scout tangential topography difference map of 360 eyes (360 patients) that underwent SMILE. Root mean square total HOAs, third order coma aberration, fourth order spherical aberration, as well as individual coefficients for vertical and horizontal coma were measured preoperatively and 3-months postoperatively. Simple linear regression analysis and piecewise regression models were used to determine the relationship between the magnitudes of total decentration and induced corneal HOAs.RESULTS. The mean total decentration distance from the corneal vertex was 0.36 6 0.22 mm (range, 0.02-1.27 mm). There were significant differences in total HOAs, coma, vertical and horizontal comas, and spherical aberration between preoperative and 3-month postoperative assessments. Significant relationships between the magnitudes of total decentration and induced corneal HOAs were noted. Subgroup analysis according to the degree of total decentration (group I, total decentered displacement 0.335 mm; and group II, total decentered displacement >0.335 mm) revealed that induced changes in total HOAs, coma, vertical coma, and spherical aberration were significantly larger in group II than in group I. CONCLUSIONS.A minimal degree of decentration was closely related to a smaller induction of corneal HOAs. Efforts to optimize centration are critical for achieving better surgical outcomes in SMILE.

Prospective, Randomized, Contralateral Eye Comparison of Functional Optical Zone, and Visual Quality After SMILE and FS-LASIK for High Myopia

“…Four kinds of aberrations were analyzed because of their clinical importance: spherical aberration (SA), vertical coma, horizontal coma, and total HOAs. 14 …”

Review on Centration, Astigmatic Axis Alignment, Pupil Size and Optical Zone in SMILE

“…The normal corneal vertex could be measured by corneal topography machines, with a Scheimpflug camera and/or a Placido system. 9,10 Corneal vertex, a stable reference of the cornea, has been recommended to be the central point of alignment for laser corneal refractive surgeries, because it has been proven to be closest to the corneal intercept of the visual axis. 7,11–13…”

“…12 It is noteworthy that vertical decentration was observed more common among the lenticule decentrations, and postoperative induced HOAs, including vertical coma and spherical aberration occurred more frequently among the surgeons at their early learning stage. 10,11,17,18…”

Characteristics of Pupil Offset in Young Asian Adults With Mild-Moderate and High Myopia

“…Accurate centration is crucial in refractive surgery because decentered treatment may result in undesirable visual outcomes. 5 Previous studies have shown that CV is an ideal ablation center with fewer postoperative higher-order aberrations (HOAs) introduced than PC. 6 , 7 With the increase in HOAs, there are a series of complications related to postoperative visual qualities, such as poor night vision, glare, monocular diplopia, and astigmatism.…”