Das biomechanische E-Staging: In-vivo-Biomechanik beim Keratokonus

Zusammenfassung

Die ABCD-Klassifikation des Keratokonus nach Belin ermöglicht eine Stadieneinteilung des Keratokonus basierend auf den Kriterien Vorder- (A) und Rückflächenverkrümmung (B), dünnster Pachymetrie (C) und bestkorrigiertem Visus mit Brille (D). Diese Parameter ermöglichen auch eine Progressionsbeurteilung, berücksichtigen jedoch nicht die korneale Biomechanik. Die korneale Biomechanik ermöglicht mit dem Corvis ST (Oculus, Wetzlar, Deutschland) zunächst die Trennung zwischen gesunden und Keratokonus-Hornhäuten mittels Corvis Biomechanischem Index (CBI) und Tomografisch-Biomechanischem Index (TBI). Bei hoher Reliabilität der Corvis-ST-Messungen in unterschiedlichen Keratokonus-Stadien wurde daher ein biomechanischer Parameter für Keratokonus-Hornhäute entwickelt, der eine biomechanische Stadieneinteilung des Keratokonus ermöglicht und der auf dem linearen Term des CBI basiert. Dieser Corvis Biomechanische Faktor (CBiF) ist zugleich Grundlage der Einführung des biomechanischen E-Stagings, was die ABCD-Klassifikation um den Eckpfeiler der kornealen Biomechanik erweitert. Der Artikel zeigt Stärken und Limitationen der ABCDE-Klassifikation auf. Der (vermeintlich) „einseitige Keratokonus“ erweist sich zumeist als Momentaufnahme einer stark asymmetrisch ausgeprägten Keratektasie. Der reguläre Astigmatismus ist mitunter eine wichtige Differenzialdiagnose zur Keratektasie und schwierig von dieser abzugrenzen. Zudem wird die Anwendung des biomechanischen E-Stagings zur Progressionsbeurteilung des Keratokonus und nach Behandlung mittels kornealem Crosslinking oder Implantation intrakornealer Ringsegmente demonstriert und diskutiert.

Schlüsselwörter

Keratokonus - ABCDE-Klassifikation - E-Staging - Biomechanik - Corvis Biomechanischer Faktor CBiF

Publication History

Received: 30 November 2022

Accepted: 14 April 2023

Article published online:
22 June 2023

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