Corneal High-Order Aberrations and Backscatter in Fuchs' Endothelial Corneal Dystrophy

      Purpose

      Suboptimal visual acuity after endothelial keratoplasty has been attributed to increased anterior corneal high-order aberrations (HOAs). In this study, we determined anterior and posterior corneal HOAs over a range of severity of Fuchs' endothelial corneal dystrophy (FECD).

      Design

      Cross-sectional study.

      Participants

      A total of 108 eyes (62 subjects) with a range of severity of FECD and 71 normal eyes (38 subjects).

      Methods

      All corneas were examined by using slit-lamp biomicroscopy to determine the severity of FECD versus normality. Fuchs' endothelial corneal dystrophy corneas were categorized as mild, moderate, or advanced according to the area and confluence of guttae and the presence of clinically visible edema. Normal corneas were devoid of any guttae. Wavefront errors from the anterior and posterior corneal surfaces were derived from Scheimpflug images and expressed as Zernike polynomials through the sixth order over a 6-mm diameter optical zone. Backscatter from the anterior 120 μm and posterior 60 μm of the cornea also was measured from Scheimpflug images and was standardized to a fixed scatter source. Variables were compared between FECD and control eyes by using generalized estimating equation models to adjust for age and correlation between fellow eyes.

      Main Outcome Measures

      High-order aberrations, expressed as root mean square of wavefront errors, and backscatter of the anterior and posterior cornea.

      Results

      Total anterior corneal HOAs were increased in moderate (0.61±0.27 μm, mean ± standard deviation; P = 0.01) and advanced (0.66±0.28 μm; P = 0.01) FECD compared with controls (0.47±0.16 μm). Total posterior corneal HOAs were increased in mild (0.22±0.09 μm; P = 0.017), moderate (0.22±0.08 μm; P < 0.001), and advanced (0.23±0.09 μm; P < 0.001) FECD compared with controls (0.16±0.03 μm). Anterior and posterior corneal backscatter were higher for all severities of FECD compared with controls ( P ≤ 0.02, anterior; P ≤ 0.001, posterior).

      Conclusions

      Anterior and posterior corneal HOAs and backscatter are higher than normal even in early stages of FECD. The early onset of HOAs in FECD might contribute to the persistence of HOAs and incomplete visual rehabilitation after endothelial keratoplasty.

      Abbreviations and Acronyms:

      CCT ( central corneal thickness), CI ( confidence interval), ECDe ( effective endothelial cell density), FECD ( Fuchs' endothelial corneal dystrophy), GEE ( generalized estimating equation), HOA ( high-order aberration), SU ( scatter units)
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