Xiaoying He1, Qin He2, Minjie Yuan1, Zhi Fang1, Kai Zhang1, Tiepei Zhu1, Wei Han3. 1. Department of Ophthalmology, Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China. 2. Department of Ophthalmology, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China. 3. Department of Ophthalmology, Eye Center of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China. hanweidr@zju.edu.cn.
Abstract
PURPOSE: The aim of this study is to evaluate morphological features of corneal flap/cap and the correlations with corneal higher-order aberrations (HOAs) changes after femtosecond laser in situ keratomileusis (FS-LASIK) and small incision lenticule extraction (SMILE). METHODS: This was a retrospective study. Pre- and postoperative (1 and 3 months) corneal HOAs were assessed with Pentacam HR. The corneal flap/cap thickness at 32 points (± 1.5 mm, ± 2 mm, ± 2.5 mm, and ± 3 mm from the corneal vertex on meridian 0°/45°/90°/135°) were measured using anterior segment optical coherence tomography at 3 months postoperatively. Morphological features of corneal flap/cap including predictability (P), uniformity (U), and symmetry (S) were calculated and used for correlation analysis with corneal HOAs changes. RESULTS: Eighty-six eyes (44 patients) and ninety-six eyes (50 patients) were involved in FS-LASIK and SMILE groups, respectively. Significant thicker corneal flap/cap than the predicted was observed at each measuring point and meridian in both groups (difference > 2.225 μm, the within-subject standard deviation over 6-mm optical zone). There was no statistically significant difference in predictability of corneal flap/cap thickness, while U6 mm (P < .0001), U0 (P < .001), U45 (P = .002), U90 (P < .0001), U135 (P = .004), S6 mm (P < .0001), S0 (P < .001), and S90 (P < .0001) over 6 mm zone were less in SMILE than in FS-LASIK. The changes of corneal tHOAs, Z (3, - 1), Z (3, 1), and SA were significantly correlated with morphological features of corneal flap/cap. CONCLUSION: Both FS-LASIK and SMILE had good predictability in flap or cap thickness, while the uniformity and symmetry of SMILE cap were better than FS-LASIK flap. The quality of flap/cap was closely associated with the changes of corneal HOAs.
PURPOSE: The aim of this study is to evaluate morphological features of corneal flap/cap and the correlations with corneal higher-order aberrations (HOAs) changes after femtosecond laser in situ keratomileusis (FS-LASIK) and small incision lenticule extraction (SMILE). METHODS: This was a retrospective study. Pre- and postoperative (1 and 3 months) corneal HOAs were assessed with Pentacam HR. The corneal flap/cap thickness at 32 points (± 1.5 mm, ± 2 mm, ± 2.5 mm, and ± 3 mm from the corneal vertex on meridian 0°/45°/90°/135°) were measured using anterior segment optical coherence tomography at 3 months postoperatively. Morphological features of corneal flap/cap including predictability (P), uniformity (U), and symmetry (S) were calculated and used for correlation analysis with corneal HOAs changes. RESULTS: Eighty-six eyes (44 patients) and ninety-six eyes (50 patients) were involved in FS-LASIK and SMILE groups, respectively. Significant thicker corneal flap/cap than the predicted was observed at each measuring point and meridian in both groups (difference > 2.225 μm, the within-subject standard deviation over 6-mm optical zone). There was no statistically significant difference in predictability of corneal flap/cap thickness, while U6 mm (P < .0001), U0 (P < .001), U45 (P = .002), U90 (P < .0001), U135 (P = .004), S6 mm (P < .0001), S0 (P < .001), and S90 (P < .0001) over 6 mm zone were less in SMILE than in FS-LASIK. The changes of corneal tHOAs, Z (3, - 1), Z (3, 1), and SA were significantly correlated with morphological features of corneal flap/cap. CONCLUSION: Both FS-LASIK and SMILE had good predictability in flap or cap thickness, while the uniformity and symmetry of SMILE cap were better than FS-LASIK flap. The quality of flap/cap was closely associated with the changes of corneal HOAs.
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