Mild Decentration Measured by a Scheimpflug Camera and Its Impact on Visual Quality Following SMILE in the Early Learning Curve

Abstract

This study suggests that, although mild decentration occurred in the early learning curve, good visual outcomes were achieved after the SMILE surgery. Special efforts to minimize induced vertical coma are necessary.

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

“…28 In 100 eyes of 55 patients treated with SMILE, the mean total decentered distance from the corneal vertex was 0.17 6 0.09 mm (range, 0.02-0.49 mm) in an anterior elevation corneal topography map from the Scheimpflug Camera, and all eyes were within 0.50 mm of the corneal vertex. 12 Although the mean total decentration values from our study were slightly larger than those reported from other studies, techniques for calculating decentration varied. A direct comparison among the studies without considering centration analysis method should be performed with caution.…”

“…26 On the other hand, one recent study evaluating the centration following the SMILE procedure found no statistically significant difference in induced ocular aberrations, rather than purely corneal aberrations, when comparing eyes with decentered distances greater than 0.30 mm to those within 0.30 mm. 12 Although the present study had several limitations, including its retrospective design, it is the first study to investigate lenticule decentration following the SMILE procedure on the tangential topography difference map of the Keratron Scout. On the basis of the current results, we concluded that minimal decentration in myopic SMILE is related to smaller induction of total HOAs, coma, vertical coma, horizontal coma, and spherical aberration.…”

“…[8][9][10] The SMILE procedure takes place under mild suction and does not involve an eye tracking system. 11,12 Currently, the alignment of the refractive lenticule relies much on the patients' cooperation, which enables a coaxial fixation to the light at the moment of application of suction, resulting in lenticule formation centered on the corneal vertex of the coaxially fixating eye. That is, optical zone centration in myopic SMILE is targeted to the coaxial corneal light reflex, also known as the first Purkinje image, which is a major advantage in SMILE.…”

“…[24][25][26] With regards to SMILE, decentrations have been reported in the literature due to presumed difficult patient cooperation and docking. 12,27,28 In the current study, we aimed to investigate the amount of lenticule decentration following SMILE and to evaluate the relationship between the magnitudes of decentration and preoperative pupillary offset (angle kappa) on tangential topography difference maps obtained with the Keratron Scout (Optikon, Rome, Italy). Furthermore, because no established studies have been published investigating the relationship of the amount of decentration with tangential maps derived from small cone Placido-based topography to induced corneal aberrations, we wanted to determine whether the rate of induction of aberrations is comparable between small and large decentrations.…”

Small-incision lenticule extraction

“…The horizontal decentration was positively correlated with the quantity of induced horizontal trefoil; obversely, the vertical decentration did not result in HOA elevation. 57 …”