# Screening with the Bilateral Corneal Symmetry 3-D Analyzer

## TL;DR

A new tool called BiCSA and a corneal symmetry index called VBS were tested to detect keratoconus by analyzing corneal shape differences.

## Contribution

The study introduces a novel corneal symmetry index (VBS) and evaluates its effectiveness in early keratoconus detection.

## Key findings

- Keratoconus patients had significantly higher VBS scores in the central 4.0 mm zone compared to healthy controls.
- A VBS threshold of 10.4 in the central zone detected 90% of keratoconus cases with a high positive predictive value of 84.2%.
- No healthy corneas exceeded a VBS threshold of 11.4 at 4 mm, suggesting values above this require further clinical evaluation.

## Abstract

This study aimed to evaluate the effectiveness of an innovative platform (the Bilateral Corneal Symmetry 3-D Analyzer—BiCSA) and a novel corneal symmetry index (the Volume Between Spheres—VBS) in differentiating normal corneas from those with keratoconus. Pentacam imaging data from 30 healthy corneas and 30 keratoconus cases were analyzed. BiCSA was utilized to determine the VBS for each case. Statistical analyses included comparing mean VBS values between groups and assessing sensitivity, specificity, and positive predictive values (PPVs). Keratoconus patients exhibited significantly higher VBS scores compared to healthy controls, particularly within the central 4.0 mm zone (11.4 versus 6.3). Using a VBS threshold of 11.3 in the central zone identified 40% of keratoconus cases (40% sensitivity), but 100% of cases surpassing the threshold were keratoconus (100% PPV). Lowering the threshold to 10.4 increased case detection to 90% while maintaining a high PPV (84.2%). These findings suggest that VBS, particularly when focused on the central 4.0 mm zone, can be a valuable tool for early keratoconus screening and identifying potential corneal abnormalities requiring further clinical evaluation. No healthy control corneas in this study exceeded a VBS threshold of 11.4 at 4 mm, indicating that values above this warrant further investigation.