Evaluation of Dry Eye in patients with Psoriasis

Purpose: To evaluate the role of routine tear film tests such as Schirmer, tear film break up time (TBUT), Rose Bengal staining (RBS) and conjunctival impression cytology for dry eye evaluation in patients with psoriasis. Methods: A case control study was performed at two referral eye centers. Symptomatic patients with psoriasis were enrolled based on their response to (Dry Eye Scoring System, DESS©), a questionnaire of dry eye related symptoms (Table 1). They further underwent Schirmer, TBUT, RBS and conjunctival impression cytology (CIC). Age and sex matched healthy subjects, served as controls. Means of groups were compared using t tests. Sensitivity and specificity of tear film tests for dry eye diagnosis was estimated by the area under receiver operating characteristic (ROC) curve. A correlation analysis (with regression) was done between dry eye symptoms and tear function tests in both groups, respectively. Adjusted Pearson's coefficient (R2) and slopes of normal probability plots were compared; R2 >0.5 was considered significant. Results: The diagnostic accuracy of tear film tests was CIC (AUC=0.969) >TBUT (AUC=0.962)>Schirmer (AUC= 0.882)>RBS (AUC=0.880). Nelson grade (R2=0.840) correlated best with dry eye symptom severity. Schirmer (R2=0.612) and TBUT (R2=0.630) also correlated well but with a smaller magnitude. However, there was lack of correlation between symptom severity and RBS (R2=0.334). Conclusion: Nelson grade correlates better with dry eye symptom severity as compared to TBUT, Schirmer and RBS. CIC is more sensitive and specific than routine tear function tests for dry eye evaluation in patients with psoriasis.