PMC

In 7 corneas with varying severity of Fuchs dystrophy, CPTR₄ was determined from 3-5 repeated measurements. The median coefficient of variation (CV) was 1.3%. Each symbol represents a different cornea.

Agreement between two corneal specialists was only moderate (κ=0.32). The two observers agreed exactly for 30/68 eyes, and were within one grade for 57/68 eyes. Data are offset for clarity, and the number of observations is indicated.

The central-to-peripheral thickness ratio at 4 mm (CPTR₄) provided excellent discrimination between corneas with Fuchs dystrophy and normal corneas, whereas central corneal thickness measured by ultrasound (CCT_us) provided only moderate discrimination. AUC, area under curve.

CPTR₄ increased with age in normal corneas (r= 0.59, p<0.001, n=254) and corneas with mild and moderate Fuchs dystrophy (r= 0.48, p=.0008, n=42), but not in corneas with advanced Fuchs dystrophy (r= 0.14, p=0.26, n=65). After adjusting thickness ratios for age, CPTR₄ was higher in advanced Fuchs dystrophy (1.03 ± 0.07, n=65) than in mild (0.96 ± 0.06, n=28, p<0.001) or moderate (0.94 ± 0.05, n=14, p<0.001), and higher in mild and moderate Fuchs dystrophy than normal (0.87 ± 0.05, n=254 p<0.001). Regression lines: gray, mild and moderate Fuchs dystrophy; dashed, normal.

CPTR₄ was correlated with the grade of Fuchs dystrophy (r= 0.77, p<0.001, n=359); grade 0 represents corneas without Fuchs dystrophy. The regression line is a third-order polynomial indicating that there are two phases of central corneal edema; the first phase was at grades 1 to 4.5, and the second phase was at grades 5 to 6.

Left, In normal corneas, central corneal thickness (CCT) was not correlated with age (r=0.15, p=0.08, n=267), whereas peripheral corneal thickness at 4 mm from the center (PCT₄) decreased with age (r= -0.33, p<0.001, n=254). Right, In corneas with Fuchs dystrophy, CCT was not correlated with age (r= -0.08, p=0.24, n=117), whereas PCT₄ was correlated with age (r= -0.17, p=0.04, n=107) Although PCT₄ was higher in Fuchs dystrophy (650 ± 51 μm) compared to normal corneas (643 ± 43 μm, p=0.002 after adjusting thickness for age), the difference was small and clinically insignificant. All data were measured with the scanning-slit pachymeter. Solid lines, regression lines for PCT₄.