Ectasia Detection In Scheimpflug-Tomographically Normal Keratoconus Fellow Eyes Using An Anterior Segment Optical Coherence Tomography-Based Algorithm

Scheimpflug corneal tomographic analysis has become widely established in early detection of corneal ectasia. More recently, the anterior segment optical coherence tomography (AS-OCT) was introduced as a new technology in ectasia diagnostics. The Screening Corneal Objective Risk of Ectasia (SCORE) algorithm allows automated evaluation of AS-OCT corneal tomography, with positive values indicating an ectasia-suspect tomography. The aim of this study was to determine whether the Scheimpflug-tomographically normal fellow eyes of keratoconus patients are also classified as normal using the AS-OCT-based SCORE algorithm.

International Vision Correction Research Centre (IVCRC), Department of Ophthalmology, University of Heidelberg, Heidelberg, Germany.

In this monocentric cross-sectional study, 22 patients with very asymmetric ectasia (VAE) were included. 22 healthy subjects served as a control group. VAE was defined as a tomographically-significant keratoconus in one eye and normal Scheimpflug tomography in the fellow eye, according to the Belin/Ambrósio D value and the Belin-ABCD keratoconus classification (Pentacam, Oculus, Wetzlar, Germany). The AS-OCT was performed using ANTERION (Heidelberg Engineering, Heidelberg, Germany) and the SCORE values of Scheimpflug-tomographically normal eyes of VAE patients (n=22) were compared with the values of healthy eyes (n=22) using Mann-Whitney-U-test. The p-value of <0.05 was considered statistically significant. 

The median (interquartile range) SCORE value was -1.7 (1.3) in healthy eyes, -0.5 (2.2) in Scheimpflug-tomographically normal fellow eyes of VAE patients, and 11.1 (11.0) in eyes with tomographically-significant keratoconus of VAE patients. The SCORE value was positive in 9.1% (n=2) of healthy eyes, in 45.5% (n=10) of Scheimpflug-tomographically normal eyes of VAE patients, and in 100% (n=22) of eyes with tomographically-significant keratoconus. The Scheimpflug-tomographically normal keratoconus-fellow eyes of VAE patients had higher SCORE values compared to those of the control group (p<0.001).

The Scheimpflug-tomographically normal eyes of keratoconus patients showed significantly higher SCORE values compared to healthy eyes. The SCORE algorithm was able to detect early tomographic ectatic changes in 46% of the Scheimpflug-tomographically normal keratoconus-fellow eyes. The AS-OCT based SCORE can therefore serve as an alternative to the Scheimpflug-based indices in detecting corneal ectasia.