ESCRS - FP03.02 - Detection Of Subclinical Keratoconus Using Combined Anterior Segment Oct And Scheimpflug Imaging

Detection Of Subclinical Keratoconus Using Combined Anterior Segment Oct And Scheimpflug Imaging

Published 2025 - 43rd Congress of the ESCRS

Reference: FP03.02 | Type: Free paper | DOI: 10.82333/50v2-3004

Authors: David López Delgado* 1 , Denisse Angel Pereira 1 , Zaira Hernadez Gonzalez 2 , Luis Reyes Gallardo 1 , Gerardo Jose Reboso Prieto 1 , Paula Alonso Gonzalez 1 , Paula Martín Gutierrez 1

1Ophtalmology,CHUC,La Laguna,Spain, 2General practitioners,CHUC,La Laguna,Spain

Purpose

One of the main risk factors for postoperative ectasia is subclinical keratoconus, which is frequently invisible with just one imaging modality. In order to identify subclinical keratoconus, this study intends to assess the combined diagnostic value of anterior segment OCT (Optopol REVO FC 80) and Scheimpflug imaging (Sirius Plus). We aimed to improve sensitivity and specificity in comparison to stand-alone devices by combining posterior corneal elevation data, pachymetric progression indices, and epithelial thickness mapping. The study pinpoints in using important diagnostic characteristics, giving refractive surgeons a powerful tool for better surgical planning and early disease diagnosis.

Setting

  • Prospective, observational study conducted over 18 months.
  • Inclusion: 100 eyes (50 subclinical keratoconus, 50 controls based on expert evaluation and Belin/Ambrosio Enhanced Ectasia Display).
  • Ethical clearance and informed consent obtained.
  • Data from SD OCT (Optopol Revo FC 80) - epithelial thickness mapping and Stromal mappping.
  • Data from Sirius Plus tomography - Anterior and Posterior corneal topography, Pachymetry and biomechanical indices.

Methods

Imaging Devices:

  • Optopol REVO FC 80 OCT: For epithelial thickness mapping and stromal analysis.
  • Sirius Plus Scheimpflug Imaging: For anterior and posterior corneal tomography, pachymetry, and biomechanical indices.

Data Collection:

  • Sirius Plus Parameters:
    • Anterior/posterior elevation.
    • Pachymetric progression index.
    • Keratometric values and Belin/Ambrosio Enhanced Ectasia Display metrics.
  • OCT Parameters:
    • Epithelial thickness profile (central and regional variations).
    • Stromal thickness and distribution.

Statistical Analysis:

  • Sensitivity, specificity, and AUC-ROC were calculated for each modality and the combined approach.
  • Comparative analysis was conducted using paired t-tests and ANOVA.

Results

A total of 100 eyes (50 subclinical keratoconus, 50 controls) were analyzed. Sirius Plus detected abnormal posterior elevation and increased pachymetric progression index, achieving 89.0% sensitivity, 88.2% specificity, and AUC-ROC of 0.87. Optopol REVO OCT showed epithelial thickness asymmetry and stromal thinning with 91.5% sensitivity, 89.8% specificity, and AUC-ROC of 0.88. Combining modalities improved diagnostic accuracy to 94.5% sensitivity, 93.2% specificity, and AUC-ROC of 0.96. The integrated approach effectively distinguished subclinical keratoconus from normal corneas.

Conclusions

When paired with Scheimpflug imaging (Sirius Plus) and anterior segment OCT (Optopol REVO FC 80), the detection of subclinical keratoconus greatly improved. While OCT offered crucial information on stromal patterns and asymmetry in epithelial thickness, Sirius Plus showed accurate identification of posterior corneal elevation and pachymetric development. By combining these modalities, a thorough framework for early detection was provided, improving sensitivity (94.5%), specificity (93.2%), and diagnostic accuracy (AUC-ROC: 0.96).  The combined strategy lowers the risk of postoperative ectasia enabling better refractive surgery planning while being non-invasive and reliable, emphasizing multimodal imaging in keratoconus screening.