Abstract

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%.

Highlights

  • If angle kappa adjustment is not considered during the pupil positioning and tracking scan, it will lead to surgically induced decentration [2], resulting in an increase in higherorder aberrations (HOAs) after surgery [3]. erefore, adjusting the excimer laser cutting center from the pupil center to the visual axis to compensate for the offset effect of angle kappa has become the consensus among corneal refractive surgeons [4, 5]

  • By analyzing the distribution rule of the vector between the pupil center and the coaxially sighted corneal light reflex, it is intended to analyze the effect of individualized excimer laser in situ keratomileusis with different angle kappa compensation, through the percentages of 50% and 100% angle kappa compensation, on diopter and visual quality in eyes with moderate myopia. e study provides a reliable theoretical and experimental basis for the design of an optimized femtosecond laser combined with excimer laser in situ keratomileusis that meets the optical characteristics of individual human eyes

  • Compensation for angle kappa combined with various modes of personalized LASIK has a good theoretical basis, there is still a significant gap between the actual and ideal visual quality [9, 10]. e currently available [11] angle kappa adjustment is compensated according to the vector percentage between the pupil center and the corneal coaxial reflection point, but the input value is a fixed decentration

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Summary

Introduction

Erefore, adjusting the excimer laser cutting center from the pupil center to the visual axis to compensate for the offset effect of angle kappa has become the consensus among corneal refractive surgeons [4, 5]. According to the data regarding changes in angle kappa, can we obtain individual kappa angle adjustment vector percentages, find the cutting center point closest to the visual axis, and ensure that each excimer laser spot is in the exact position?. By analyzing the distribution rule of the vector between the pupil center and the coaxially sighted corneal light reflex, it is intended to analyze the effect of individualized excimer laser in situ keratomileusis with different angle kappa compensation, through the percentages of 50% and 100% angle kappa compensation, on diopter and visual quality in eyes with moderate myopia. By analyzing the distribution rule of the vector between the pupil center and the coaxially sighted corneal light reflex, it is intended to analyze the effect of individualized excimer laser in situ keratomileusis with different angle kappa compensation, through the percentages of 50% and 100% angle kappa compensation, on diopter and visual quality in eyes with moderate myopia. e study provides a reliable theoretical and experimental basis for the design of an optimized femtosecond laser combined with excimer laser in situ keratomileusis that meets the optical characteristics of individual human eyes

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