A novel grading method for superficial punctate keratopathy magnitude and its correlation with corneal epithelial permeability

Objectives: To propose a novel grading method for superficial punctate keratopathy (SPK) magnitude and to examine the quantitativeness of the method. Methods: In 351 eyes diagnosed as having dry eye syndrome, SPK was graded as follows. After fluorescein staining, the total sum of the area of SPK was graded from A0 through A3, and the density was graded from DO through D3. The grading was represented as the combination of the area and density grades. The correlation between the SPK grade and the corneal epithelial permeability to fluorescence, measured using an anterior fluorophotometer, was analyzed in the 351 eyes. Main Outcome Measures: The correlation between the fluorescein concentration in the cornea and the sum of the area and density grades. Results: The higher the density and area grades, the higher the fluorescein concentration, except for A3D2. There was a clear exponential correlation between the sum of the area and density grades and the fluorescein concentration in the cornea, measured using an anterior fluorophotometer. The regression curve was y = 61.2e(0.59x), where y is the fluorescein concentration (nanograms per milliliter), and x is the sum of the area and density grades (P<.001). Conclusions: The SPK grade is positively correlated with the corneal epithelial permeability to fluorescence, measured using an anterior fluorophotometer. Our results indicate that this grading method can be clinically useful.