Comparison of corneal consumption in correcting high with-the-rule astigmatism between refractive lenticule extraction and laser-assisted in situ keratomileusis.

Abstract

Purpose: To compare corneal thickness (CT) and corneal volume (CV) consumption after the refractive lenticule extraction and the femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) in myopic eyes with high with-the-rule (WTR) astigmatism.

Methods: 70 myopic eyes (50 patients) with high WTR astigmatism (-2.00 to -3.25 D) received refractive lenticule extraction (35 eyes) or FS-LASIK (35 eyes) in this retrospective study. Predicted central corneal thickness (CCT) consumption was obtained from the corresponding laser platform software. The CT in different positions (thinnest location, center, around the thinnest location at 2 mm, 4 mm, 6 mm rings and four different directions points in every ring), and CV in different areas (around the CCT at 3 mm, 5 mm, 7 mm, and 10 mm zone) were measured via corneal tomography before surgeries and at 1, 3, and 6-month follow-up.

Results: The results of the postoperative examination indicated that refractive lenticule extraction and FS-LASIK had proximate satisfaction, safety, accuracy, and stability. In SMILE group and FS-LASIK group, the predicted CCT consumption was 111.66 ± 13.08 μm and 103.26 ± 12.79 μm, respectively (P = 0.010). At the 6-month follow-up, the actual changes of CCT in two groups were 96.71 ± 12.88 μm and 114.74 ± 16.42 μm, respectively (P < 0.001). The reduction of CCT was overestimated by 14.94 ± 8.42 μm (P < 0.001) in SMILE group, while it was underestimated by 11.34 ± 7.61 μm (P < 0.001) in FS-LASIK group. The ΔCT (every area and each point) was significantly lower than in FS-LASIK group at 3 postoperative time points (1, 3, 6 months) in SMILE group. The data showed that ΔCV of all areas (3, 5, 7, 10-mm diameter area) in SMILE group was significantly fewer than FS-LASIK group in each follow-up.

Conclusion: Refractive lenticule extraction had less consumption in CT and CV compared with FS-LASIK in equivalent refractive error. In refractive lenticule extraction, the CCT consumption has been overrated, whereas underrated in FS-LASIK. Compared with refractive lenticule extraction, the actual CCT changes of FS-LASIK approached the predicted value.

Key messages: What is known Corneal consumption is known as the important index in the treatment of refractive lenticule extraction and the femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) for patients who suffer from myopia with astigmatism. What is new This study evaluated corneal thickness (CT) and corneal volume (CV) consumption of myopic patients with high with-the-rule (WTR) astigmatism before and after refractive lenticule extraction and FS-LASIK. There was less ΔCT and ΔCV consumption in SMILE group compared with FS-LASIK group in patients with high WTR astigmatism. The predictability of CCT consumption in FS-LASIK is better than in refractive lenticule extraction.