AUTHOR=Zhao Yu , Fu Dan , Chen Zhuoyi , Zhou Xingtao 

TITLE=Three-Year Follow-Up of Posterior Corneal Elevation in Thin Corneas After Small Incision Lenticule Extraction

JOURNAL=Frontiers in Medicine

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2022.758223

DOI=10.3389/fmed.2022.758223

ISSN=2296-858X

ABSTRACT=<sec><title>Purpose</title><p>To evaluate the changes in posterior corneal elevation in thin corneas after small incision lenticule extraction (SMILE).</p></sec><sec><title>Methods</title><p>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.</p></sec><sec><title>Results</title><p>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 (<italic>P</italic> ≥ 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 (<italic>P</italic> = 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 (<italic>P</italic> ≤ 0.006) (except for the inferior area, the 4-mm and 6-mm optical zone).</p></sec><sec><title>Conclusions</title><p>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.</p></sec><sec><title>Synopsis</title><p>Careful preoperative assessment and suitable surgical design should be taken to ensure posterior corneal stability after SMILE in thin corneas.</p></sec>