The aim of this study is to investigate the changes of visual quality and influencing factors after ray tracing-guided (RT) laser in situ keratomileusis (LASIK).

From August 2023 to December 2023, a total of 78 patients (156 eyes) with myopic astigmatism were enrolled in the Refractive Surgery of Beijing Tongren Hospital Affiliated to Capital Medical University. There were 24 males (48 eyes) and 54 females (108 eyes) with the average age of 28.5 (25.0, 34.0) years (ranging from 18 to 39 years). Patients were divided into LASIK group and RT group according to the surgical method. LASIK was performed in LASIK group, and RT LASIK was performed in RT group. The changes of visual acuity, high-order aberrations and contrast sensitivity between two groups preoperation and 6 months postoperation were compared. The spherical equivalent, high-order aberrations and contrast sensitivity conformed to the normal distribution, and were expressed as ±s. Pared t-test were used for comparison at different time points before and after surgery, and independent sample t-test was used for comparison between groups. Age was represent by median and interquartile range M (Q1, Q3), which did not follow a normal distribution according to Kolmogorov-Smirnov test.

Among the 37 patients (74 eyes) in the RT group, there were 11 males (22 eyes) and 26 females (52 eyes), with a mean age of 29.0 (23.0, 34.0) years (ranging from 18 to 39 years ). In the LASIK group consisting of 41 patients (82 eyes), there were 13 males (26 eyes) and 28 females (56 eyes), with a mean age of 28.0 (26.0, 33.0)years (ranging from 23 to 39 years). The spherical equivalent and uncorrected visual acuity in the RT group and LASIK group before surgery and at 6 months postoperatively were (-4.87±1.11)D, (0.12±0.30)D, (-5.19±1.05)D, (0.06±0.43)D, (1.21±0.26)logarithm of the minium angle of resolution (logMAR), (-0.11±0.06) logMAR, (1.14±0.24)logMAR and(-0.12±0.07)logMAR, respectively. There were statistically significant differences in the indexes within both groups before and after surgery (t=-36.79, -43.25, 42.84, 43.51; P<0.05). The root mean square values of total higher-order aberrations, coma, trefoil and spherical aberration of both eyes in the RT group and LASIK group before surgery and at 6 months postoperatively were (0.40±0.17)μm, (0.59±0.20)μm, (0.44±0.15)μm, (0.72±0.24)μm, (0.21±0.13)μm, (0.44±0.20)μm, (0.22±0.13)μm, (0.49±0.2)μm, (0.20±0.10)μm, (0.15±0.08)μm, (0.20±0.10)μm, (0.22±0.10)μm, (0.14±0.11)μm, (0.16±0.12)μm, (0.14±0.10)μm and (0.29±0.25)μm, respectively. There were statistically significant differences in the two groups before and after surgery( t=9.86, 10.00, 8.33, -6.13, 6.80, 6.72, 8.38, -6.61; P<0.05). The fourth-order spherical aberration of the right and left eyes in the LASIK group preopertion and postoperation were (0.02±0.18)μm, (0.19±0.34)μm, (-0.01±0.16)μm and (0.19±0.33)μm, respectively, and there were statistically significant differences (t=-4.27, -5.30; P<0.05). The contrast sensitivity values of the two groups at medium and high spatial frequencies of 3.0 c/d, 6.0 c/d, 12.0 c/d and 18.0 c/d before and after surgery were 1.91±0.12, 2.06±0.13, 1.77±0.23, 2.06±0.16, 1.16±0.34, 1.53±0.35, 0.67±0.48, 0.87±0.42, 1.89±0.23, 2.01±0.15, 1.71±0.35, 1.90±0.26, 1.05±0.53, 1.40±0.29, 0.57±0.42 and 0.80±0.42. There were statistically significant differences within both groups between preoperative and postoperative measurements (t=-6.89, -9.07, -6.19, -3.08, -3.76, -4.85, -5.59, -4.10; P<0.05). At the medium spatial frequencies of 3.0 c/d, 6.0 c/d and 12.0 c/d, the increase in contrast sensitivity was greater in the RT group than in the LASIK group, with statistically significant differences (t=2.36, 4.89, 2.53; P<0.05).

The high-order aberrations of RT LASIK group increase after surgery, but which are lower than those of the LASIK group. The main increase comes from coma with symmetrical change in both eyes, while spherical aberration shows no significant change. Contrast sensitivity of postoperation at medium and high spatial frequencies is higher than that of preoperation, and it is superior to the LASIK group at medium frequencies.