Correlation of Arachadonic Acid–Derived Tear–Film Lipids and Ocular Surface Disease in Dry Eye
To examine the relationship between arachadonic acid (AA)-derived lipids in the tear film and clinically familiar measures of ocular surface disease in patients with dry eye.
Tear film samples were collected by micropipette from 18 subjects with dry eye (DE) symptoms. All patients underwent a comprehensive dry eye evaluation including measurement of ocular surface staining, Schirmer's testing, and tear breakup time (TBUT). Liquid chromatography/mass spectrometry-based lipidomic analysis was performed targetting arachadonic acid (AA) and its metabolites, prostaglandin E2 (PGE2), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) in the tear film samples.
AA and its downstream metabolites (e.g., 5-HETE), PGE2, DHA and EPA were detected in the tears of DE patients. Mean AA was 15,858 pg/sample (SD 18,247, range 0-68,737), PGE2 12.2 pg/sample (SD 3.2), EPA 44.5 pg/sample (SD 45, range 23.7-157), and DHA 2,190 pg/sample (SD 1,602, range 796-6,747). Patients with abnormal ocular surface parameters (Schirmers, staining, TBUT) had elevated AA and DHA which trended toward significance. More importantly, the ratio of anti-inflammatory (EPA+DHA) over pro-inflammatory (AA) mediators was positively correlated with corneal staining and negatively correlated with Schirmers (p<0.05). PGE2 levels positively correlated with AA levels (r=0.48, p=0.04) and negatively with TBUT (-0.58, p=0.01).
Tear film AA and its downstream metabolites appear to be important correlates of ocular surface disease. These findings may help to design new strategies for protection of the ocular surface in patients with DE.