Objectively quantifying facial erythema in rosacea aided by the ImageJ analysis of VISIA red images

BACKGROUND: Facial erythema, a prominent characteristic of rosacea, causes concern to both the patient and doctor. In clinical practice, commonly used erythema severity subjective assessment tools lack objectivity and are less comprehensive. Even with images taken by the VISIA(®) system, diffused erythema is difficult to segment and evaluate fully due to the automatic threshold segmentation method. This study aimed to explore a more objective and scientific erythema quantification tool with the aid of the ImageJ software analysis of the red area images taken by the VISIA(®) system. MATERIALS AND METHODS: Patients with rosacea were enrolled and assessed for the clinical severity of their illness using various stools—the standard grading systems (SGS) for rosacea, investigator's global assessment (IGA), and clinician's erythema assessment (CEA). Facial images in the red area mode of the VISIA(®) system were further analyzed by the ImageJ for the relative intensity of redness and percentage of erythema area; the correlation with the scores of the subjective grading systems was evaluated. RESULTS: This study included 201 patients (195 females and 6 males). The relative intensity of redness was positively correlated to the SGS, IGA, and CEA scores (0.688, 0.725, and 0.718, respectively) (p < 0.001). The percentage of erythema area was positively correlated to the SGS, IGA, and CEA scores (0.615, 0.666, and 0.656, respectively) (p < 0.001). CONCLUSION: We demonstrated a more objective and precise method of assessing the severity of facial erythema rosacea, which could comprehensively assess the severity by both the area and intensity of facial erythema.