Abstract
Purpose :
Scheimpflug imaging can be used to classify and predict the prognosis of Fuchs endothelial corneal dystrophy (FECD) based on abnormalities in pachymetry map and posterior surface tomographic patterns. In this study, we determined posterior corneal aberrations and their relationship to visual acuity in eyes with FECD based on these tomographic findings.
Methods :
Eyes with a range of severity of FECD and age-matched eyes with normal corneas were examined by corneal specialists and enrolled in a cross-sectional study. Tomography maps derived from Scheimpflug imaging (Pentacam, Oculus) were evaluated by a masked observer for 3 features of clinical/subclinical edema: loss of parallel isopachs, displacement of the thinnest point of the cornea, and the presence of focal posterior surface depression (towards the anterior chamber). Posterior corneal high-order aberrations (HOAs, 6 mm-diameter optical zone) extrapolated from tomography were expressed as Zernike coefficients. High-contrast best-corrected visual acuity (BCVA, measured by e-ETDRS) in pseudophakic FECD eyes without other comorbidities was correlated with total HOAs. Significances of differences and correlations were assessed by generalized estimating equation models; P-values were adjusted for multiple comparisons.
Results :
Posterior corneal total HOAs in FECD with all 3 tomographic features (0.33 ± 0.15 µm [mean ± SD], n=45) and with 1 or 2 tomographic features (0.23 ± 0.09 µm, n=21) were increased compared to normal corneas (0.17 ± 0.03 µm, n=78; p<0.001 and p=0.01, respectively), whereas no difference was found between FECD with no tomographic features (0.17 ± 0.03 µm, n=46) and normal corneas (p=0.99). In pseudophakic FECD eyes, BCVA correlated with posterior corneal total HOAs (r=0.76, p<0.001, n=28); BCVA was 0.18 ± 0.16 logMAR (all 3 tomographic features present), 0.15 ± 0.24 logMAR (1 or 2 features present), and 0.01 ± 0.10 logMAR (no features present).
Conclusions :
In FECD, posterior corneal HOAs derived from Scheimpflug images increase when pachymetry map and posterior elevation patterns are abnormal. BCVA strongly correlates with posterior corneal HOAs in FECD, and remains excellent when tomography is normal. These findings suggest that BCVA in FECD does not decrease until tomographic patterns of subclinical edema occur. Scheimpflug tomography should be evaluated prior to surgical intervention in FECD.
This is a 2020 ARVO Annual Meeting abstract.