We measured eDNA abundance in tear fluid using the PicoGreen dye assay and correlated these findings with symptom severity and clinical signs in patients with dry eyes. Symptom analysis was performed using the OSDI questionnaire. The OSDI scores were 35.8 (5.2) for patients with nonautoimmune DED, 34.5 (4.1) for patients with autoimmune DED (e.g., Sjögren's syndrome), and 54.0 (5.2) for patients with GVHD. The OSDI score for all patients with dry eyes was significantly higher than the 3.4 (0.7) for healthy control subjects (
P < 0.05). The average aqueous tear production quantities in patients with nonautoimmune DED, autoimmune DED, and GVHD were 6.6 (1.1), 1.6 (0.8), and 0.5 (0.2) mm, respectively. Tear production in all patients with dry eyes was significantly lower than the 23.1 (1.7) mm seen in healthy control subjects (
P < 0.05). The severity of ocular surface disease was assessed using Rose Bengal dye staining. The Rose Bengal ocular surface staining scores were 2.8 (0.6) for patients with nonautoimmune DED, 4.6 (0.7) for patients with autoimmune DED, and 5.5 (0.7) for patients with GVHD. Healthy control subjects had no ocular surface staining with Rose Bengal dye. The staining score was significantly higher in all the dry eye groups compared with that in healthy control subjects (
P < 0.05). The corneal and conjunctival Rose Bengal staining scores were also analyzed independently. Corneal Rose Bengal staining scores in patients with nonautoimmune DED, autoimmune DED, and GVHD were 1.6 (0.5), 2.4 (0.5), and 3.1 (0.6), respectively. Conjunctival Rose Bengal staining scores in patients with nonautoimmune DED, autoimmune DED, and GVHD were 1.3 (0.3), 2.2 (0.4), and 2.4 (0.5), respectively. Both corneal and conjunctival staining scores were significantly higher for all patients with dry eyes compared with those for healthy control subjects (
P < 0.05). The PicoGreen dye assay was used to measure eDNA abundance in tear fluid after a 5-minute incubation. Tears of patients with nonautoimmune DED had a mean eDNA abundance of 2.9 (0.6) μg/mL. Tears of patients with autoimmune DED had a mean eDNA abundance of 5.2 (1.2) μg/mL. Tears of patients with GVHD had a mean eDNA abundance of 9.1 (2.3) μg/mL. The mean eDNA abundance in all tear fluid samples of patients with dry eyes was higher than the 1.4 (0.2) μg/mL in healthy control subjects (
P < 0.05). Significant differences were noted between the GVHD and nonautoimmune DED groups for eDNA abundance (
P = 0.02), OSDI score (
P = 0.02), aqueous tear production (
P < 0.001), and Rose Bengal ocular surface staining score (
P = 0.03). Between the GVHD and autoimmune DED groups, a significant difference was only noted for OSDI score (
P = 0.05). Correlation analysis was performed to evaluate the association of tear fluid eDNA abundance with ocular signs and symptoms (
Table). Tear fluid eDNA abundance correlated best with corneal Rose Bengal staining (
r = 0.55). Tear fluid eDNA abundance correlated weakly with the Schirmer I test result (
r = −0.39) and OSDI score (
r = 0.35) (
Table).