In this randomized clinical trial, patients with Meibomian gland dysfunction aged 50 year and more will be enrolled. The Meibomian gland dysfunction diagnosis will confirmed by a cornea specialist. The enrolled patients will be randomly allocated to the treatment and placebo group. The patients in treatment group will receive topical vitamin D every 6 hours daily (25 Microgram/cc or 1000 IU). The control group will receive the same-shape packed drop without vitamin D. The patients in both group will receive the conventional treatment including hot compress and shampoo scrub.

The primary outcome is the change in Ocular surface disease index and 5-Item Dry Eye Questionnaire score assessed before the topical treatment and every one-months until 3 months. The secondary outcome measures are Tear breakup time, Schirmer test, Corneal fluorescein staining, Meibomian gland expressibility.

The grader and the patients will blind to the study group.

Inclusion Criteria:

• patients aged more than 50 years old and suffering from dry eye caused by meibomian gland dysfunction.

Exclusion Criteria:

• Patients with Vitamin D deficiency
• Patients taking Vitamin D systemic Supplementation
• Patient with prior ocular surgeries within previous 6 months.
• Patient with other causes of dry eye, such as aqueous tear deficiency or ocular surface disease