Detection of Subclinical Keratoconus With a Validated Alternative Method to Corneal Densitometry

Purpose: To enhance the current standards of subclinical keratoconus screening based on the statistical modeling of the pixel intensity distribution of Scheimpflug images. Methods: Scheimpflug corneal tomographies corresponding to 25 corneal meridians of 60 participants were retrospectively collected and divided into three groups: controls (20 eyes), subclinical keratoconus (20 eyes), and clinical keratoconus (20 eyes). Only right eyes were selected. After corneal segmentation, pixel intensities of the stromal tissue were statistically modeled using aWeibull probability density function from which parameter alpha (pixel brightness) was derived. Further, data were transformed to polar coordinates, smoothed, and interpolated to build amap of the corneal alpha parameter. The discriminative power of the method was analyzed using receiver operating characteristic curves. Results: The proposed platform-independent method achieved a higher performance in discriminating subclinical keratoconus from control eyes (90.0% sensitivity, 95.0% specificity, 0.97 area under the curve [AUC]) than the standard method (Belin-Ambrosio enhanced ectasia display), which uses only corneal morphometry (85.0% sensitivity, 85.0% specificity, 0.80 AUC). Conclusions: Analysis of light backscatter at the cornea successfully discriminates subclinical keratoconus from control eyes, upgrading the results previously reported in the literature. Translational Relevance: The proposed methodology has the potential to support clinicians in the detection of keratoconus before showing clinical signs.