Scheimpflug Imaging Characteristics of Fuchs Endothelial Corneal Dystrophy

Abstract

 

Purpose

 

Anterior corneal haze (backscatter), measured by confocal microscopy, increases in Fuchs endothelial corneal dystrophy (FECD). In clinical practice, non-contact Scheimpflug cameras are faster and simpler to use than confocal microscopy. This study assessed Scheimpflug image characteristics across a range of severity of FECD.

 

Methods

 

Eighty-three eyes of 46 participants (median age, 67 years; range, 44-89 years) were examined by using slit-lamp biomicroscopy. FECD severity was graded clinically based on the area and confluence of guttae, and the presence of edema (modified Krachmer scale). Eyes were grouped as controls (grade 0, n = 16), or mild (grade 1-2, n = 25), moderate (grade 3-4, n = 24), or advanced (grade 5-6, n = 18) FECD. Central corneal haze in the anterior 120 μm, mid-stroma, and posterior 60 μm of the cornea was measured from Scheimpflug images (Pentacam) standardized to a fixed scatter source and expressed as “Scatter Units” (SU), the concentration of Amco Clear (GFS Chemicals) that gave the same image brightness as the corneal image. Effective endothelial cell density (ECD_e), an objective measure of disease severity, was determined from the area of guttae and local cell density in confocal microscopy images (ConfoScan 4) of the same corneas. Central corneal thickness (CCT) was measured by ultrasonic pachymetry. Variables were compared between groups by using generalized estimating equation (GEE) models to account for correlation between fellow eyes. Correlations were assessed by using Pearson coefficients with significances determined by using GEE models.

 

Results

 

Central corneal haze in mild, moderate, and advanced FECD was higher than normal in all three depths of the cornea (Table). ECD_e was correlated with anterior (r = -0.55, p < 0.001), mid-stromal (r = -0.43, p = 0.006), and posterior (r = -0.59, p < 0.001) corneal haze. CCT in mild, moderate, and advanced FECD was higher than normal (Table). CCT was correlated with anterior (r = 0.41, p < 0.001), mid-stromal (r = 0.31, p < 0.001), and posterior (r = 0.41, p = 0.031) corneal haze.

 

Conclusions

 

Scheimpflug imaging detected increased haze at all depths of the cornea in FECD, and in the earliest stages of FECD. Haze was associated with increasing disease severity (decreasing ECD_e). Non-contact Scheimpflug photography might provide a simple method of assessing FECD and its follow-up in clinical practice.