The aim of this study is to investigate the patterns of corneal epithelial remodeling and related influencing factors after topography-guided laser in situ keratomileusis (TOPO-G LASIK).

A total of 119 patients (237 eyes) based on TOPO-G LASIK from May 2021 to July 2024 were retrospectively included in Beijing Tongren Hospital, Capital Medical University. There were 28 males (56 eyes) and 91 females (181 eyes) with an average age of 27.9±4.7 years (ranging from 18 to 40 years old). Patients were divided into the high myopia group (≤-6.00 D) and the moderate-to-low myopia group (>-6.00 D) based on the manifest refractive spherical equivalent (MRSE). The epithelial thickness (ET) of 17 regions in total within the 6 mm corneal range, which included 1 central zone (0 to 2 mm), as well as the inner ring zone (2 to 5 mm) and the outer ring zone (5 to 6 mm), was measured by the anterior segment optical coherence tomography preoperatively and 1, 3, 6, 12 months postoperatively. The age, visual acuity, MRSE, corneal thickness and epithelial thickness were all normally distributed and described as ±s. Paired t-tests were used in both groups before and after surgery, and independent sample t-tests were used between the two groups at different time points. And a mixed-effects model was applied to further explore the specific factors affecting postoperative ET changes.

The MRSE, uncorrected distance visual acuity, best corrected distance visual acuity, and central corneal thickness were (-7.66±1.29) D, (1.35±0.28) logarithm of the minium angle of resolution (logMAR), (-0.04±0.05) logMAR, and (535.12±22.98) μm in the high myopic group and (-4.27±1.26) D, (1.08±0.39) logMAR, (-0.05±0.04) logMAR, and (529.63±29.76)μm in the moderate-to-low myopic group. The uncorrected distant visual acuity of the moderate-to-low myopia group was better than that of the high myopia group (t=0.79, P<0.05), while no statistical differences were in the best corrected distance visual acuity and central corneal thickness (t=0.21, 0.21; P>0.05) between the two groups. The central 2 mm average ET of the two groups at 1, 3, 6, 12 months postoperatively was (55.17±4.19)μm, (57.73±4.41)μm, (57.94±3.99)μm, (58.35±3.70)μm, (53.99±4.45)μm, (54.74±3.24)μm, (55.36±3.36)μm, (56.66±4.34)μm, respectively; and the inner 2 to 5 mm ring average ET was (58.79±3.90)μm, (61.08±3.89)μm, (61.11±3.48)μm, (61.78±3.27)μm, (56.23±4.43)μm, (56.93±2.84)μm, (57.52±3.31)μm, (58.56±4.29)μm, respectively; and the outer 5 to 6 mm ring average ET was (56.84±3.57)μm, (58.94±3.12)μm, (58.55±3.18)μm, (59.32±2.87)μm, and (55.68±4.19)μm, (56.29±2.73)μm, (56.76±2.92)μm, (57.19±3.98)μm, respectively. Both groups increased compared with those preoperatively, and the high myopic group showed significant increases in the average corneal ET in the central 2 mm (t=0.20, 0.38, 0.38, 0.27; P<0.05), the inner ring 2 to 5 mm zone (t=0.43, 0.62, 0.55, 0.53; P<0.05), and the outer ring 5 to 6 mm zone (t=0.27, 0.52, 0.58, 0.41; P<0.05) at 1, 3, 6, 12 months postoperatively compared with the moderate-to-low myopic group. The superotemporal, temporal, inferotemporal, and inferior ET of the 2 to 5 mm and 5 to 6 mm zones gradually increased over time, and the increase in the high myopic group was higher than that in the moderate-to-low myopic group. The results of the mixed-effects model analysis showed that the ablation depth and MRSE were negatively correlated with Δ2 mm ET (β=-1.27, -1.87; P<0.05); the follow-up time at 3, 6, 12 months postoperatively was positively correlated with Δ2 mm epithelium (β=1.72, 1.92, 2.70; P<0.05). The interaction effect of cutting depth and follow-up time was positively correlated with Δ2 mm ET. There was statistical significance at 3 months and 6 m (β=0.60, 0.73; P<0.05).

Corneal epithelial remodeling after TOPO-G LASIK was mainly concentrated in the inferotemporal, inferior, and temporal regions of the inner and outer ring zones. The ET increase in the high myopia group was higher than that in the moderate-to-low group at all postoperative times. However, epithelial remodeling continued in both groups within 1 year after surgery and had not reached a stable state. Preoperative MRSE was the main determinant of postoperative epithelial remodeling. Ablation depth could not function independently of time, which influenced central epithelial remodeling through a time-dependent interaction effect with a more significant impact in the mid-to-long term. Therefore, enhanced mid-to-long-term follow-up is required.