Corneal aberrations after small-incision lenticule extraction versus Q value-guided laser-assisted in situ keratomileusis

Abstract

Previous studies compared ocular aberration and visual quality after small-incision lenticule extraction (SMILE) and Q value-guided femtosecond laser-assisted in situ keratomileusis (Q-FS-LASIK), but anterior corneal surface aberration properties are poorly known. This study aimed to compare the changes in anterior corneal surface aberration after SMILE versus Q-FS-LASIK. This was a prospective, observational cohort study. Patients with myopia and myopic astigmatism underwent SMILE or Q-FS-LASIK at Hangzhou MSK Eye Hospital between January 2015 and November 2015. High order aberration (HOA), primary spherical aberration (PSA), primary coma aberration (PCA), primary vertical coma aberration (PVCA), and primary horizontal coma aberration (PHCA) were assessed using pre- and postoperative Sirius scanning. Both surgery were associated with significant increases in postoperative HOA, PSA, and PCA (both groups P < .01). In the SMILE group ( n = 51), the variations in HOA, PSA, and PCA were no longer significant after postoperative week 2 ( P > .05). In the Q-FS-LASIK group ( n = 73), the variations in HOA and PCA were no longer significant after postoperative day 1 ( P > .05). In the SMILE group, the 3-month changes in PCA were not correlated with spherical, spherical equivalent (SE), and spherical plus cylinder measurements. Cylinder measurements were not correlated with HOA, PSA, and PCA. In the Q-FS-LASIK group, the 3-month changes in PCA correlated with spherical, SE, and spherical plus cylinder measurements. Both SMILE and Q-FS-LASIK resulted in an increase in HOA, PSA, and PCA at postoperative day 1, but Q-FS-LASIK introduced lower HOA and showed better stability. Spherical measurement was related to PSA.

Corneal Higher-Order Aberrations Measurements: Precision of SD-OCT/Placido Topography and Comparison with a Scheimpflug/Placido Topography in Eyes After Small-Incision Lenticule Extraction

“…Similar to other corneal refractive surgeries, SMILE increases corneal HOAs, such as SA and coma. Zhang et al [28] used Sirius to measure the total corneal HOAs RMS, SA, and coma at 3 months after SMILE over a diameter of 5.0 mm, and found values of 0.46 ± 0.18 lm, 0.22 ± 0.08 lm and 0.25 ± 0.11 lm, respectively; these were significantly higher than those before SMILE (0.24 ± 0.06 lm, 0.10 ± 0.04 lm and 0.1 ± 0.06 lm, respectively). The authors of a number of studies have pointed out that the increase in corneal HOAs after SMILE was mainly related to the deviation between the center of the ablated corneal stroma and the center of the pupil [9,10].…”

Effect of Limbal Incision Positions on Corneal Q-Value in Cataract Surgery: A Retrospective Study of Monofocal IOL and Trifocal IOL

“…In ZCB00 group, at 6.0 mm corneal diameter, the temporal corneal Q value was -0.08±0.16 mm preoperatively, -0.11±0.13mm at 1 week postoperatively and -0.11±0.18mm Review of the literatures, the corneal Q value has a positive linear correlation with posterior corneal astigmatism, and the significant positive correlation was found between the primary spherical aberration [12]. And also, Jun Zhang et al, proved that Q value-guided femtosecond laser-assisted in situ keratomileusis introduced lower HOA and better stability than small-incision extraction [13]. As a result, corneal Q value is coming to the forefront of interest of refractive-correction cataract surgeons.…”

Analysis of Asphericity and Corneal Longitudinal Spherical Aberration of 915 Chinese Myopic Adult Eyes

“…Changes in the spread of focal points may optimize visual quality or depth of field according to clinical needs. [1][2][3] The Q value is a quantitative indicator of asphericity and is defined as the radius of curvature change from the apex to the periphery. 4,5 Spherical-like aberration, which belongs to the category of transverse aberration, refers to the root mean square (RMS) of the zero-frequency Zernike coefficients above fourth-order.…”