Fuchs' endothelial corneal dystrophy: subjective grading versus objective grading based on the central-to-peripheral thickness ratio.
OBJECTIVE
To assess interobserver agreement between 2 corneal specialists grading Fuchs' dystrophy clinically and to determine if the corneal central-to-peripheral thickness ratio (CPTR) may be an alternative and objective metric of disease severity.


METHODS
Cross-sectional study.


METHODS
Forty-five eyes (26 subjects) with mild and moderate Fuchs' dystrophy, 73 eyes (60 subjects) with advanced Fuchs' dystrophy, and 267 eyes (142 subjects) with normal corneas.


METHODS
Corneas with Fuchs' dystrophy were graded by 2 corneal specialists based on the confluence and area of guttae and the presence or absence of edema. Central corneal thickness (CCT) and peripheral corneal thickness at 4 mm from the center (PCT4) were measured by using scanning-slit pachymetry. The value of CPTR4 was the quotient of CCT and PCT4.


METHODS
Interobserver agreement for clinical grade and CPTR4.


RESULTS
Interobserver agreement for clinical grading of Fuchs' dystrophy was moderate (κ = 0.32; 95% confidence interval, 0.19-0.45). In normal corneas, CCT was not correlated with age (r = -0.10; P = 0.28; n = 267), PCT4 decreased with age (r = -0.33; P<0.001; n = 254), and CPTR4 increased with age (r = 0.59; P<0.001; n = 254). Central corneal thickness was higher in Fuchs' dystrophy (652 ± 61 μm; n = 118) than in normal corneas (559 ± 31 μm; n = 267; P<0.001). Also, PCT4 was higher in Fuchs' dystrophy (650 ± 51 μm; n = 107) than in normal corneas (643 ± 43 μm; n = 254; P<0.001 after adjusting thickness for age). Furthermore, CPTR4 was higher in advanced Fuchs' dystrophy (1.03 ± 0.07; n = 65) than in mild and moderate Fuchs' dystrophy (0.95 ± 0.07; n = 42; age-adjusted P<0.001), which in turn was higher than in normal corneas (0.87 ± 0.05; n = 254; age-adjusted P<0.001). Finally, CPTR4 was highly correlated with clinical grade of Fuchs' dystrophy (r = 0.77; P<0.001; n = 361), was repeatable (median coefficient of variation, 1.3%), and provided excellent discrimination between Fuchs' dystrophy and normal corneas (area under the receiver operator characteristic curve, 0.93).


CONCLUSIONS
Agreement between corneal specialists for the subjective and morphologic clinical grading of Fuchs' dystrophy is only moderate. The corneal CPTR is an objective, repeatable, and possibly functional, metric of severity of Fuchs' dystrophy that warrants further investigation to determine its role in monitoring disease progression and predicting the need for keratoplasty.
Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota 55905, USA.
Daniel J
DJ
Repp
David O
DO
Hodge
Keith H
KH
Baratz
Jay W
JW
McLaren
Sanjay V
SV
Patel
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003315:Cornea / Q000473:pathology*; D063171:Corneal Pachymetry / Q000379:methods*; D003430:Cross-Sectional Studies; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D005642:Fuchs' Endothelial Dystrophy / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D055815:Young Adult