ABSTRACT
PURPOSE: The changes in tear film lipid layer thickness (LLT) after artificial tears application using LipiView®II interferometer were assessed. METHODS: We performed a prospective study of patients with dry eye disease. All subjects underwent measurement of tear film break-up time, Schirmer test, ocular surface staining, meibomian gland evaluation, and subjective score assessment using the Ocular Surface Disease Index. All subjects were randomly assigned to 1 of 3 groups using table of random numbers (group 1, sodium hyaluronate [HA] 0.1% eye drops without preservatives; group 2, HA 0.3% eye drops without preservatives and group 3, HA 0.1% with benzalkonium chloride 0.003%). LLT was measured before, immediately after and 1 hr, 3 hrs, and 6 hrs after artificial tears application. Additionally, the patients were divided into 2 subgroups depending on the presence of meibomian gland dysfunction (MGD) and further evaluated. RESULTS: Significant change in LLT was observed at 3 hrs after artificial tears instillation. LLT in groups 1 and 2 showed significant changes over time (p < 0.01 and p < 0.01, respectively). However, LLT in group 3 showed no change. LLT was unchanged in patients without MGD. Conversely, in MGD patients, a significant difference in LLT between groups 1 and 2 was observed immediately after and 1 hr and 3 hrs after instillation of artificial tears (p = 0.04, p < 0.01 and p = 0.02, respectively) but not at 6 hrs. However, no significant difference in LLT between groups 1 and 3 was observed in MGD patients. CONCLUSIONS: LLT after instillation of artificial tears measured using LipiView®II interferometer was affected by artificial tear concentration and presence of preservatives. Additionally, the presence of MGD can impact the pattern of LLT changes induced by artificial tear instillation. Therefore, LLT measurements using LipiView®II interferometer require at least a 6-hrs interval after use of eye drops, especially for patients with MGD or using artificial tears with preservatives.