ESCRS - FP18.04 - Comparing Regional Stress-Strain Index Maps Between Post-Laser Vision Correction Normal And Ectasia Patients

Comparing Regional Stress-Strain Index Maps Between Post-Laser Vision Correction Normal And Ectasia Patients

Published 2026 - 44th Congress of the ESCRS

Reference: FP18.04 | Type: Free paper | DOI: 10.82333/1bed-s715

Authors: A/Prof. Ke Ma 1 , Mr Keyi Pei 2 , Dr Robert Herber 3 , A/Prof. Lele Cui 4 , Dr Nanji Lu* 1

1Department of Ophthalmology,West China Hospital Sichuan University,Chengdu,China, 2School of Engineering,Sichuan University,Chengdu,China, 3Department of Ophthalmology,University Hospital Carl Gustav Carus Dresden,Dresden,Germany, 4Department of Ophthalmology,Wenzhou Medical University,Wenzhou,China

Purpose

To characterize regional corneal stiffness using Stress–Strain Index (SSI) maps in post–laser vision correction (LVC) normal and post-LVC ectasia eyes, and to evaluate the diagnostic performance of SSI map–derived parameters.

Setting

West China Hospital Sichuan University and Eye Hospital of Wenzhou Medical University

Methods

A total of 296 post-LVC normal eyes (148 patients) and 54 post-LVC ectasia eyes (39 patients) were included. All eyes underwent Scheimpflug-based tomography and dynamic air-puff tonometry (Pentacam and Corvis ST). SSI maps were generated to quantify regional corneal stiffness distribution. Regional SSI values and spatial asymmetry parameters (e.g., superior–nasal [SN] minus inferior–temporal [IT] regions) were calculated. Diagnostic performance was assessed using receiver operating characteristic (ROC) curve analysis and area under the curve (AUC).

Results

Post-LVC normal eyes demonstrated significantly higher SSI values compared with post-LVC ectasia eyes (all P < 0.001). ROC analysis revealed that, among independent regional values, the inferior paracentral region demonstrated the highest diagnostic ability (AUC = 0.916; 0.64 ± 0.12 vs. 0.30 ± 0.22), followed by the IT paracentral (AUC = 0.892) and central regions (AUC = 0.890). For spatial asymmetry parameters, the highest diagnostic accuracy was achieved with the paracentral superior–inferior (S–I) difference (AUC = 0.922), closely followed by the paracentral SN–IT difference (AUC = 0.912).

Conclusions

Corneal stiffness reduction in post-LVC ectasia is highly localized rather than uniformly distributed. SSI map–derived asymmetry and regional parameters demonstrate outstanding diagnostic capability and may serve as valuable tools for the clinical evaluation of post-LVC ectasia.