Investigation of Ocular Tear Ferning in Controlled and Uncontrolled Diabetic Subjects

Objectives: To investigate the ocular tear film in controlled and uncontrolled diabetes mellitus (DM) subjects and the relationship between dry eye and diabetes. Methods: One hundred twenty-four diabetes adults (65 male and 59 female, with 62 controlled and 62 uncontrolled DM) were assessed by McMonnies dry eye questionnaire, tear break-up time (TBUT), phenol red thread (PRT) test. In addition, tear samples were collected from the lower tear meniscus of right eyes and dried onto glass slides under controlled room temperature (25 degrees C) and humidity (40%). The glass slides were observed using a digital microscopy and the tear ferning (TF) patterns observed were graded based on Masmali TF grading scale. Patients with a HbA1c value below 6.5% were defined as "controlled DM" and those with a HbA1c value above 6.5% were defined as "uncontrolled DM." The Spearman's correlation coefficient was used to determine the relationship between various tests. Results: Several subjects having dry eye varied depending on the test used. McMonnies questionnaire scores suggested that 28 subjects (23%) showed dry eye (score > 14.5), of whom 23 subjects (82%) showed uncontrolled diabetes. The TF patterns showed that 44 subjects (35.5%) showed dry eyes (Grade >= 2), of whom 32 subjects (72.7%) showed uncontrolled diabetes. Phenol red thread test found that 46 subjects (37%) showed dry eye (wetting < 10 mm), of whom 38 subjects (82.6%) showed uncontrolled diabetes. Tear break-up time found that 57 subjects (46%) showed dry eye (time < 10 sec), of whom 45 subjects (78.9%) showed uncontrolled diabetes. In controlled diabetic subjects, TF grades showed medium negative correlations with both TBUT and PRT (-0.374 and -0.349, respectively). In uncontrolled subjects, TF grades have a strong negative correlation with TBUT (-0.539) and a medium negative correlation with PRT (-0.410). Conclusions: Dry eye disease is common in diabetic subjects, particularly in people with poor diabetic control. Uncontrolled blood glucose level seemed to be a risk factor for dry eye syndrome. Tear ferning test showed a correlation between diabetes and dry eye in diabetic subjects and can be used as a reliable test to evaluate the quality of the ocular tear film.