BRUSH CYTOLOGY SCORE SYSTEM (BCSS) GRADES INFLAMMATION IN DRY EYE PATIENTS

Purpose. Despite increasing scientific evidence on the role of sub-clinical ocular inflammation in dry eye, an evaluation system of conjunctival brush cytology has not been validated yet. We propose a Brush Cytology Scoring System (BCSS) as a reliable method to diagnose and score ocular surface inflammation in dry eye. Methods. 10 normal subjects and 15 patients with dry eye of various severity were included. Clinical signs were assessed using a score of 0 (none) to 3 (severe) for each eye and the subjective symptoms with the OSDI questionnaire. Levels of exudated serum albumin and IL-6 in tears were evaluated. Conjunctival cytology samples were obtained from the lower and upper lids, processed and independently examined at LM. The number of neutrophils, eosinophils, basophils, lymphocytes and monocytes were counted in 30 consecutive microscopic fields at 400x and staged on a scale of 0-4, sum BCSS ranged 0-20. Statistical evaluation was performed by applying the unpaired Student’s t-test and the Pearson correlation test (significance p<0.05). BCSS was also analysed for sensitivity, specificity, ROC curves, likelihood ratio LR+, positive (PPV) and negative (NPV) predictive values. Results. BCSS was positively correlated to clinical sign score, OSDI score, exudated serum albumin and IL-6 in either control (Pearson’s correlation test respectively p<0.05, p<0.001, p<0.001 and p<0.01) and in dry eye patients (p< 0.001, p<0.01 and p<0.003). BCSS > 6 was selected as cut off value for moderate dry eye (LR+ 12,7; PPV 24,5), BCSS >11 was selected as cut off value for severe dry eye (LR+ 21,3; PPV 32,6). Conclusions. BCSS can be applied in any trained laboratory; our findings suggest it is correlated with clinical signs and symptoms, showing good diagnostic performance to grade inflammation in dry eye patients. This work was supported in part through a grant from the Fondazione Cassa di Risparmio in Bologna to Prof. Emilio Campo