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Published on: March 1, 2015
Temporal redistribution of cap and residual stromal thickness after SMILE
Markus V Olsen1, Anne V Lyngstadaas, Wen Zhou
1From the Department of Medical Biochemistry, Oslo University Hospital, Oslo (Olsen, Lyngstadaas, Utheim), Department of Ophthalmology (Utheim), Oslo University Hospital, Oslo, Institute of Clinical Medicine (Olsen, Lyngstadaas), Faculty of Medicine, University of Oslo, Oslo, Department of Ophthalmology (Stojanovic), University Hospital North Norway, Tromsø, Institute of Clinical Medicine (Zhou, Stojanovic), Faculty of Medicine, University of Tromsø, Tromsø, Department of Ophthalmology (Utheim, Chen), Sørlandet Hospital, Arendal, Department of Ophthalmology (Utheim, Chen), Vestre Viken Hospital Trust, Drammen, Faculty of Health Sciences, National Centre for Optics, Vision and Eye Care, University of South Eastern Norway (Utheim, Badian, Chen), Kongsberg, Norway; and the Department of Ophthalmology (Wang), The First Affiliated Hospital of Northwestern University, Xi´an, Shanxi, China.
Purpose:
To investigate corneal sublayer alterations during the postoperative period after small-incision lenticule extraction (SMILE).
Setting:
Synslaser clinic, Oslo, Norway.
Study Design:
Retrospective.
Methods:
Patients who underwent SMILE for treating myopia were included. The thicknesses of the corneal epithelium, cap, stromal part of the cap (StromaCap), residual stromal bed (StromaRes), and total stroma (StromaTot) were measured using spectral-domain optical coherence tomography at 1 day, 1 week, 1 month, 3 months, and 6 months postoperatively. Postoperative changes in the corneal sublayer thicknesses were analyzed and correlated with changes in spherical equivalence and anterior and posterior keratometry (K).
Results:
The study was based on analyses of the right eyes of 51 patients. From 1 day to 6 months postoperatively, the corneal epithelium, cap, StromaCap, StromaRes, and StromaTot thicknesses increased from 54.4 ± 4.0 µm to 57.3 ± 5.2 µm; 137.1 ± 5.5 µm to 140.3 ± 5.1 µm; 82.7 ± 5.9 µm to 82.8 ± 6.3 µm; 375.0 ± 40.8 µm to 381.4 ± 30.6 µm; and 457.6 ± 41.1 µm to 462.1 ± 36.7 µm, respectively. Between 1 month and 6 months postoperatively, the increase in anterior K correlated significantly with the thickening of the cap (r = 0.37, P = .03) and the stromal component of the cap (r = 0.36, P = .04) within the central cornea.
Conclusions:
The post-SMILE remodeling behavior between the anterior (StromaCap) and posterior (StromaRes) stroma were dissimilar. There was a significant correlation between changes in anterior K and the central cap and the stromal component of the cap. This might be because of biomechanical changes, tissue remodeling, and wound healing or a combination of some or all of the aforementioned processes.
