Abstract
Purpose :
Scheimpflug imaging can be used to predict the prognosis of Fuchs endothelial corneal dystrophy (FECD) by detecting tomographic patterns consistent with the presence of subclinical corneal edema based on posterior elevation and pachymetry maps. In this study, we developed a severity scale for FECD based on these maps, and evaluated intra- and inter-observer variation for assessing severity.
Methods :
In a cross-sectional study, eyes with a range of severity of FECD were examined by two cornea specialists and underwent Scheimpflug imaging (Pentacam, Oculus). An ordinal scale was developed to assess the severity of FECD ranging from normal (grade 1) to severe edema (grade 6), based on loss of parallel isopachs, displacement of the thinnest point of the cornea, and posterior surface depression within the central 4 mm of the cornea. Subtle findings suspicious for early tomographic edema were defined as grade 2. Progressive severity of edema was based on the depth of posterior surface depression (mild, moderate, advanced, and severe were grades 3-6, respectively). Masked and randomized images were presented to both cornea specialists without associated clinical information. Intra-observer (1 observer evaluating the same images on 2 occasions separated by 2 weeks) and inter-observer agreement were assessed by using the kappa statistic (κ) with 95% confidence interval (CI), and McNemar’s test for significant differences.
Results :
Exact agreement between repeated assessments by one observer occurred for 97% (277/286) of eyes (κ=0.96, CI 0.93 to 0.99, p=0.88). All disagreements were by 1 grade only. Exact agreement between assessments by both observers occurred for 85% (244/286) of eyes (κ=0.81, CI 0.76 to 0.86, p=0.12). Disagreements were by 1 grade for 40 eyes and by 2 grades for 2 eyes, and mainly occurred because one observer assigned increased severity relative to the other when determining normal tomography from those with suspicious findings of early edema.
Conclusions :
Assessing the severity of FECD from Scheimpflug tomography has excellent intra- and inter-observer agreement based on the proposed severity scale. The lower inter-observer agreement was a result of lack of sufficient standardization between observers rather than limitations of the imaging technology. Further investigation is needed to determine if this severity assessment can detect tomographic and clinical progression.
This is a 2021 ARVO Annual Meeting abstract.