Retroillumination Photography Analysis Enhances Clinical Definition of Severe Fuchs Corneal Dystrophy.

PURPOSE: Retroillumination photography analysis (RPA) provides an objective assessment of the number and distribution of guttae in Fuchs corneal dystrophy. Here, we assess its correlation with clinical grading using slit-lamp biomicroscopy across varying levels of severity.
METHODS: Retroillumination photographs were conducted for 95 affected corneas with slit-lamp flash photography after pupillary dilation. Individual guttae were counted manually and the position of individual points recorded. Clinical grading using the Krachmer scale was documented for each eye during examination, and regression analyses were performed to identify the strength of association with number of guttae. We assessed range at each stage of clinical grading and used the Mann-Whitney U test to assess whether clinical grading levels demonstrated successively higher numbers of guttae.
RESULTS: Krachmer score ranged from 1 to 5, with mean of 2.6. Mean numbers of guttae at each level of severity were 289 (1+), 999 (2+), 2669 (3+), 5474 (4+), and 7133 (5+). Each stage demonstrated significantly higher numbers of guttae than its preceding level except from 4+ to 5+ (P = 0.30), consistent with the definition of 4+ as the highest level defined by the presence of guttae. Higher levels of clinical grading were associated with larger ranges of guttae (P < 0.01). A linear regression model resulted in a strong fit between RPA and Krachmer score (r = 0.81).
CONCLUSIONS: In this largest study of RPA data and comparison with subjective clinical grading of Fuchs dystrophy severity, RPA correlates strongly and demonstrates enhanced definition of severity at advanced stages of disease.