New severity grading system for Fuchs endothelial corneal dystrophy using anterior segment optical coherence tomography.

Abstract

To report a new severity grading system for Fuchs endothelial corneal dystrophy (FECD) using anterior segment optical coherence tomography (AS-OCT). This observational case series included 75 eyes of 43 patients with FECD and 33 eyes of 33 healthy subjects. Pachymetry and posterior elevation maps were used to determine the AS-OCT-based grading scores. FECD severity was graded from 0-3 as follows: 0, normal; 1, guttae only; 2, stromal oedema; and 3, epithelial and stromal oedema. We further investigated the central corneal thickness (CCT), thinnest corneal thickness (TCT), anterior and posterior best-fit spheres (BFS), and the distance between the central cornea and the thinnest point. Thirty-three eyes were graded as 0, four as 1, thirteen as 2, fourteen as 3, twenty-nine as 4, eleven as 5 and four as 6 by the modified Krachmer grade. Thirty-three, 41, 30 and 4 eyes were graded as 0, 1, 2 and 3, respectively, by the AS-OCT-based grading system. The inter-observer agreement was 100% for the AS-OCT-based grading system. The CCT, TCT, posterior BFS, and distance between the central cornea and thinnest point were significantly different between AS-OCT-based grades (p=0.0001, 0.0001, 0.0036 and 0.0001, respectively). Anterior BFS was not significantly different with the AS-OCT-based grades (p=0.1184). We devised a new severity grading using only objective evaluation and quantitatively demonstrated corneal thickening, predominant flattening of the posterior corneal surface compared with the anterior surface, and displacement of the thinnest point away from the central cornea with FECD progression.