Purpose. To analyze the distribution of the offset between the pupil center and the coaxially sighted corneal light reflex (P-Dist), the effects of 50% and 100% angle kappa adjustments on refractive and visual quality in patients with moderate myopia were investigated. Methods. A randomly selected 254 patients (254 eyes) with moderate myopia who underwent femtosecond laser-combined LASIK were examined. During the operation, the P-Dist of the patients was recorded by the x- and y-axis eyeball-tracking adjustment program of the WaveLight Eagle Vision EX500 excimer laser system. Preoperatively and 3 months postoperatively, the WaveLight® ALLEGRO Topolyzer was used to measure the pupil size and center position, and the wavefront sensor was used to measure the wavefront aberrations. The visual function tester (OPTEC 6500) measured contrast sensitivity. Results. The average P-Dist was 0.220 ± 0.102 mm. When the P-Dist >0.220 mm, the postoperative residual cylinder was 0.29 ± 0.34 D in the group with the 50% adjustment and 0.40 ± 0.32 D in the 100% group, which was significantly higher than the 50% group P = 0.036 . The coma was 0.21 ± 0.17 μm in the 50% adjusted group and 0.34 ± 0.25 μm in the 100% group, which was significantly higher than that in the 50% group P = 0.021 . At the 1.5 c/d spatial frequency, contrast sensitivity in the adjusted 100% group was significantly lower than that in the 50% group under visual glare conditions P = 0.039 . Conclusion. The postoperative visual acuity and spherical equivalent were not affected in the two groups. However, when P-Dist >0.220 mm, the residual astigmatism and coma were lower in the 50% group. Individualized operations for those with moderate myopia and large-angle kappa in which 100% adjustment is chosen may not result in a better visual quality effect than 50%.

Background To explore the dynamic distribution of pupil size and center,the eccentricity distribution of angle kappa, and its correlation with other biomechanics about suitable for excimer laser refractive surgery. Methods Randomly selected 225 patients (407 eyes) who underwent femtosecond laser combined with excimer laser in situkeratomileusis,preoperative use of Wavelight Allegro Topolyzer Corneal Topography ( Wavelight Laser Technologies AG, Erlangen, Germany ) to measure the pupil size and center position, the German Wavelight EX500 excimer Laser (500Hz) records the deviation between the pupil center and the coaxially sighted corneal light reflex when the patient is supine. Results The average displacement distribution of P-Dist (the eccentricity between the pupil center and the coaxially sighted corneal light reflex point) is 0.225 ± 0.102 mm, and 80% of the eyes are ≤ 0.30 mm.The coaxially sighted corneal light reflex point is mainly deviated to the superior temporal side of the corneal center (34%).Under the dark light condition, the x-axis of the left eye was: -0.046 ± 0.091 mm, the x-axis of the right eye was: -0.152 ± 0.084 mm, with statistical difference ( P = 0.015) (the right eye shifted to the temporal side), the y-axis direction had no statistical change ( P = 0.062). The WTW was positively correlated with changes of pupil diameter (dark pupil diameter-bright pupil diameter) ( r = 0.270, P <0.001).The SE and measured centroid shift was negative correlated ( r = - 0.214, P = 0.002). Conclusion The pupil of the left eye becomes smaller, the anterior chamber becomes shallower, and the angle kappa increases relative to the right eye.In patients with large WTW, a darker light environment is maintained during the operation to improve the efficiency of pupil matching.The dynamic change of angle kappa in high myopia population is small.

Background: To investigate the characteristics and distribution of anterior surface wavefront aberrations in patients suitable for corneal refractive surgery. Methods: A total of 121 myopic patients (121 eyes, 18-45 years old) who underwent corneal refractive surgery were randomly selected by the Pentacam anterior segment analysis system with a spherical equivalent (SE) of -0.25 to -10.00 D. The corneal anterior aberrations (total higher-order aberration; spherical aberration; Coma; Trefoil) and Q and K values were detected, and a correlation analysis of the relevant parameters was carried out. Results: The root-mean-square (RMS) of the third to sixth order aberrations of the corneal anterior wavefront aberrations at a 6mm analysis diameter showed a decreasing trend in patients suitable for the corneal refractive surgery, and the RMS of the third order aberrations accounted for 62.92% of the total HOAs. The coma ratio (coma/total cornea higher-order aberrations) was increased with the increasing diopters, while the spherical aberration ratio (spherical aberration/ total cornea higher-order aberrations) was not changed. In addition, the spherical aberration was 0.203±0.082 μm (range: 0.061 to 0.503 μm), and the Q30 was -0.19±0.03 (range: -0.58 to 0.31). There were significant differences in the coma aberrations of preoperative corneal anterior surface (3, 1) between the low, middle and high myopia groups (P=0.013). The spherical equivalent was positively correlated with the corneal coma of the anterior corneal surfaces (R=-0.241, P=0.009), and the Q value was positively correlated with the total higher-order aberrations (R=0.326, P<0.001). Conclusions: Individual wavefront aberrations on the anterior surfaces of the cornea are comparatively different, and the Zernike coefficients are related to the degree of myopia. Spherical aberrations are the most overriding aberrations of the cornea.

Background To investigate the characteristics and distribution of anterior and posterior surface wavefront aberrations in patients suitable for corneal refractive surgery. Methods Sixty myopic patients (120 eyes, 14-46 years old) who underwent corneal refractive surgery were randomly selected by the Pentacam anterior segment analysis system with a spherical equivalent (SE) of -1.50 to -12.00 D. The corneal anterior and posterior aberrations (higher-order aberration, HOA; spherical aberration, SA; Coma; Trefoil) and Q and K values were detected, and a correlation analysis of the relevant parameters was carried out. Results The root mean square (RMS) values from 3 to 6 (RMS 3 to 6) of the whole eye higher-order wave surface aberrations at a 6.0 mm pupil diameter showed a decreasing trend in patients with corneal refractive surgery, and an RMS value of 3 accounted for 62.92% of the total HOAs. The coma ratio increased with increasing diopter, while the spherical aberration ratio was not changed. In addition, the spherical aberration was 0.203 ± 0.082 μm (range: 0.061 to 0.503 μm), and the Q30 was -0.19 ± 0.03 (range: -0.58 to 0.31), which showed a normal distribution. There were significant differences in coma aberrations (3, 1) in the low, middle and high myopia groups (P=0.013). The spherical equivalent was positively correlated with corneal coma (R = -0.241, P = 0.009), and the Q value was positively correlated with total higher-order as well as spherical aberrations (R = 0.326, P <0.001; R = 0.675, P <0.001). Conclusions Individual wavefront aberrations on the anterior and posterior surfaces of the cornea are comparatively different, and the Zernike coefficients are related to the degree of myopia. Spherical aberrations are the most overriding aberrations of the cornea.