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Abstract：
OBJECTIVE: To evaluate the changes in posterior corneal elevation in thin corneas after small incision lenticule extraction (SMILE).
METHODS: In this prospective study, 97 eyes of 97 patients undergoing SMILE were recruited. Eyes were categorized into the following groups based on the preoperative minimum central corneal thickness (CCT): group A (37 eyes, 480-499 μm), group B (30 eyes, 500-529 μm), and group C (30 eyes, 530-560 μm). The posterior corneal surface was measured with a Pentacam over a 3-year follow-up period. Changes in the posterior corneal elevation at the central point (PCE), thinnest point (PTE), and predetermined area were measured.
RESULTS: No iatrogenic keratectasia was observed during the follow-up period. The mean changes in PCE, PTE, and the inferior area in group A were 1.14 ± 3.40 μm, -0.11 ± 3.20 μm, and -0.26 ± 1.23 μm, respectively (P ≥ 0.125). Although statistically significant change in the central-4 mm area was noted, the value was quite small (0.98 ± 1.67 μm) and was not higher than that in the other two groups (P = 0.003). For all three groups, the elevation remained stable or showed a backward change in the central annulus, while there was a small forward displacement in the 6-mm optical zone. In group A, changes in elevation values yielded negative statistical correlations with residual bed thickness and CCT (P ≤ 0.006) (except for the inferior area, the 4-mm and 6-mm optical zone).
CONCLUSIONS: With a strict preoperative assessment, SMILE achieved good safety and efficacy in correcting myopia in thin corneas and enabled a stable posterior corneal surface over a 3-year follow-up period.
CONCLUSIONS: Careful preoperative assessment and suitable surgical design should be taken to ensure posterior corneal stability after SMILE in thin corneas.
METHODS: In this prospective study, 97 eyes of 97 patients undergoing SMILE were recruited. Eyes were categorized into the following groups based on the preoperative minimum central corneal thickness (CCT): group A (37 eyes, 480-499 μm), group B (30 eyes, 500-529 μm), and group C (30 eyes, 530-560 μm). The posterior corneal surface was measured with a Pentacam over a 3-year follow-up period. Changes in the posterior corneal elevation at the central point (PCE), thinnest point (PTE), and predetermined area were measured.
RESULTS: No iatrogenic keratectasia was observed during the follow-up period. The mean changes in PCE, PTE, and the inferior area in group A were 1.14 ± 3.40 μm, -0.11 ± 3.20 μm, and -0.26 ± 1.23 μm, respectively (P ≥ 0.125). Although statistically significant change in the central-4 mm area was noted, the value was quite small (0.98 ± 1.67 μm) and was not higher than that in the other two groups (P = 0.003). For all three groups, the elevation remained stable or showed a backward change in the central annulus, while there was a small forward displacement in the 6-mm optical zone. In group A, changes in elevation values yielded negative statistical correlations with residual bed thickness and CCT (P ≤ 0.006) (except for the inferior area, the 4-mm and 6-mm optical zone).
CONCLUSIONS: With a strict preoperative assessment, SMILE achieved good safety and efficacy in correcting myopia in thin corneas and enabled a stable posterior corneal surface over a 3-year follow-up period.
CONCLUSIONS: Careful preoperative assessment and suitable surgical design should be taken to ensure posterior corneal stability after SMILE in thin corneas.
摘要：
目的：评估小切口微透镜摘除（SMILE）后薄角膜后角膜抬高的变化。
方法：在这项前瞻性研究中，招募97例接受SMILE治疗的患者的97只眼。根据术前最小中央角膜厚度（CCT）将眼睛分为以下几组：A组（37只眼，480-499μm),B组(30只眼,500-529μm),和C组(30只眼，530-560μm)。在3年的随访期内，用Pentacam测量了角膜后表面。中央点（PCE）的后角膜抬高的变化，最薄点（PTE），并测量预定面积。
结果：在随访期间未观察到医源性角膜扩张症。PCE的平均变化，PTE,A组的下面积为1.14±3.40μm，-0.11±3.20μm,和-0.26±1.23μm，分别为(P≥0.125)。尽管注意到中央4毫米区域的统计显着变化，该值很小（0.98±1.67μm），不高于其他两组（P=0.003）。对于所有三个小组，海拔保持稳定或显示中心环的向后变化，而在6毫米的光学区域有一个小的向前位移。在A组中,海拔值的变化与残余床层厚度和CCT呈负统计相关性（P≤0.006）（下层区域除外，4毫米和6毫米光学区)。
结论：经过严格的术前评估，SMILE在矫正薄角膜近视方面取得了良好的安全性和有效性，并在3年的随访期内实现了稳定的后角膜表面。
结论：应采取仔细的术前评估和适当的手术设计，以确保薄角膜SMILE术后后角膜的稳定性。
方法：在这项前瞻性研究中，招募97例接受SMILE治疗的患者的97只眼。根据术前最小中央角膜厚度（CCT）将眼睛分为以下几组：A组（37只眼，480-499μm),B组(30只眼,500-529μm),和C组(30只眼，530-560μm)。在3年的随访期内，用Pentacam测量了角膜后表面。中央点（PCE）的后角膜抬高的变化，最薄点（PTE），并测量预定面积。
结果：在随访期间未观察到医源性角膜扩张症。PCE的平均变化，PTE,A组的下面积为1.14±3.40μm，-0.11±3.20μm,和-0.26±1.23μm，分别为(P≥0.125)。尽管注意到中央4毫米区域的统计显着变化，该值很小（0.98±1.67μm），不高于其他两组（P=0.003）。对于所有三个小组，海拔保持稳定或显示中心环的向后变化，而在6毫米的光学区域有一个小的向前位移。在A组中,海拔值的变化与残余床层厚度和CCT呈负统计相关性（P≤0.006）（下层区域除外，4毫米和6毫米光学区)。
结论：经过严格的术前评估，SMILE在矫正薄角膜近视方面取得了良好的安全性和有效性，并在3年的随访期内实现了稳定的后角膜表面。
结论：应采取仔细的术前评估和适当的手术设计，以确保薄角膜SMILE术后后角膜的稳定性。
