Evaluation of Factors Affecting the Tear-film Lipid Layer Thickness

In this study, the investigators aim to determine the effects of age, sex, history of ocular surgery and contact lens use, and ocular surface and meibomian gland parameters on the lipid layer thickness (LLT) in normal subjects and patients with dry eye syndrome. Patients with dry eye syndrome and subjects with a healthy ocular surface will be enrolled. All participant will underwent LLT measurement with a LipiView interferometer, tear meniscus height measurement using optical coherence tomography, tear film break-up time (TBUT) determination, corneal and conjunctival staining, Schirmer's test, examination of the lid margins and meibomian glands, and assessment using the Ocular Surface Disease Index(OSDI) questionnaire.