A novel scraping cytology score system (SCSS) grades inflammation in dry eye patients.

PURPOSE

We propose a conjunctival Scraping Cytology Scoring System (SCSS) as a reliable method to diagnose and score ocular surface inflammation in dry eye.

METHODS

Twenty normal subjects and 46 patients with dry eye of various severities were included in the study. Clinical signs were scored 1-4; an Ocular Surface Disease Index (OSDI) questionnaire was used to grade subjective symptoms. Concentrations of serum albumin and interleukin-6 (IL-6) in tears were evaluated. Scraped conjunctival cytology samples were processed and examined with light microscopy. The number of inflammatory cells was staged and sub-scores were assigned. SCSS resulted from their sum and ranged from 0-12. Statistical evaluation was performed by applying the unpaired Student's t-test and the Spearman's correlation test (significance p < 0.05). SCSS was also analyzed for sensitivity, specificity, ROC curves, likelihood ratio LR+, positive (PPV) predictive value.

RESULTS

SCSS was positively correlated to clinical sign score, OSDI score, exudated serum albumin, and IL-6 in either control (Spearman's correlation test always p < 0.05) and in dry eye patients (respectively, p < 0.0001, p < 0.01, p < 0.05, and p < 0.0001). SCSS >or= 4 was selected as the cut-off value for moderate dry eye (LR+ 10,9; PPV 22,5), SCSS >or= 9 was selected as the cut-off value for severe dry eye (LR+ 15,6; PPV 26,2).

CONCLUSIONS

SCSS can be applied in any trained laboratory. It is correlated with clinical signs and symptoms, and it shows a diagnostic performance to grade inflammation in dry eye, comparable to more expensive cytokine assay.