Preoperative Tomographic Risk Factors And Clinical Characteristics Of Corneal Ectasia Following Small Incision Lenticule Extraction: A Retrospective Case-Series Study
Published 2026 - 44th Congress of the ESCRS
Reference: FP18.12 | Type: Free paper | DOI: 10.82333/q0ky-7n32
Authors: Dr Xiaoyu Zhang* 1 , Ling Sun 1 , Xingtao Zhou 1
1Eye Institute and Department of Ophthalmology,Eye & ENT Hospital,Shanghai,China
Purpose
To characterize ectasia following small incision lenticule extraction (SMILE) and investigate the associations between preoperative tomographic parameters and the occurrence of post-SMILE ectasia.
Setting
This was a retrospective case-series study.
Methods
We reviewed preoperative corneal tomography characteristics and surgical parameters in 18 patients (25 eyes) who developed ectasia after SMILE, including 7 bilateral cases and 11 unilateral cases. All cases were followed for at least 3 years post-SMILE. Evaluated parameters included age, tomographic indices (e.g., corneal thickness, asymmetry, and higher-order aberrations), residual stromal bed (RSB), percent tissue altered (PTA), and Ectasia Risk Score System (ERSS) scores.
Results
Among the 25 post-SMILE ectasia eyes, 5 eyes (20%) had a PTA <40%, and 13 eyes (52%) had an RSB ≤300 µm. The ectasia cases exhibited thinner preoperative central corneal thickness (mean 512 ± 28 µm), higher PTA (mean 38.2 ± 5.1%), lower RSB (mean 285 ± 42 µm), and elevated ERSS scores (mean 4.2 ± 1.8). Abnormal posterior elevation was noted in 68% of cases.
Conclusions
Post-SMILE ectasia can occur even with PTA <40% or RSB >300 µm, highlighting the limitations of these thresholds in isolation. Comprehensive preoperative tomographic evaluation, focusing on posterior corneal changes and PTA, is essential for identifying at-risk patients and optimizing SMILE candidacy.