Enhanced Screening for Ectasia Risk: Multimodal Refractive Imaging Observations From the Fellow Unoperated Eye of Patients With Post-Laser In Situ Keratomileusis Ectasia

Abstract

The aim of this study was to report multimodal refractive imaging findings that may predict ectasia susceptibility on nonoperated eyes of patients who developed post-LASIK ectasia in the fellow eye. This is a retrospective case series. The nonoperated fellow eyes of 5 patients who had unilateral LASIK with progressive ectasia underwent a comprehensive ophthalmologic evaluation and multimodal refractive imaging (MRI), including Pentacam HR and Corvis ST (Oculus; Wetzlar, Germany), along with segmental OCT (RTVue; Optovue, Inc, Fremont, CA). Different objective indices and parameters from the Pentacam, Corvis ST, and OCT were analyzed. None of the 5 cases showed ectasia detection on the Pentacam TKC (topographic keratoconus classification), and inferior–superior (IS) asymmetry values were lower than 1.0 D in all 5 cases. Corneal thicknesses at the thinnest points measured with the Pentacam were 530, 466, 517, 488, and 511 µ, and with the OCT were 512, 460, 508, 480, and 495 µ, in cases 1to 5, respectively. The keratoconus risk scoring system based on OCT measurements demonstrated a high risk in 2 patients. The BAD-D (Belin-Ambrósio Enhanced Ectasia Deviation) was higher than 1.22 in all 5 cases and higher than 1.6 in 2 cases. Four cases had ARTmax (Ambrósio Relational Thickness to the meridian with maximal progression increase) lower than 390. The PRFI (Pentacam Random Forest Index) was equal or higher than 0.12 in all 5 cases, and enhanced posterior elevation, which is calculated using data from the standard elevation map, excluding a 3.5-mm area centered on the thinnest point, was abnormal in all 5 cases. The value of the current version of the tomographic biomechanical index (TBI V1), derived from artificial intelligence (AI) algorithms, which integrate Scheimpflug-based tomography and biomechanical data, was equal or higher than 0.29 in 3 cases. Signs of ectasia susceptibility were detected in all nonoperated eyes based on multimodal imaging. These findings support the clinical relevance of such analysis when screening for ectasia risk among candidates for refractive surgery.