Abstract
BACKGROUND: Early detection of keratoconus is essential for maximizing the potential of cross-linking treatments designed to halt keratoconus progression, minimizing the risks of iatrogenic ectasia as well as reducing the need for corneal transplantation. This review focuses on the progress that has been made in the early detection of keratoconus using biomechanical and topographical properties derived from three different technologies, namely the ocular response analyser (ORA), corneal visualization Scheimpflug tonometer (Corvis ST) and optical coherence tomography (OCT). METHOD: A PubMed search was performed using the keywords of 'early keratoconus', 'subclinical keratoconus', 'forme fruste keratoconus', 'very asymmetric ectasia with normal topography/tomography' and 'ocular response analyser' and/or 'Corvis ST'/'corneal visualized Scheimpflug tomographer/tomography' and/or 'optical coherence tomography/tomographer'. RESULTS: The integration of biomechanical parameters and corneal morphological data from the topography/tomography or OCT, or the assessment of bilateral asymmetry, has demonstrated improvement in the accuracy of diagnosing early-stage keratoconus. CONCLUSIONS: As measurement principles differ depending on the technique used for keratoconus assessment, comprehensive metrics may be needed to reflect subtle anterior or posterior corneal changes and help identify eyes with very early ectasia. Although clinical experts have always, and will most likely, continue to play a pivotal role in decision-making for early keratoconus diagnosis, future developments in technology and AI may lead to enhanced early detection in the future.