This is a parallel randomized controlled trial for the treatment of dry eye disease. The main objective is to investigate the efficacy and safety of the use of insulin eye drops in the control of moderate-severe dry eye disease. Topical insulin drops will be compared to artificial tears in improving the ocular surface interface in patients with dry eye disease over 1 year period.

Patients fulfilling the selection criteria will be enrolled from eye OPD of KTH. A written informed consent will be taken after explaining the purpose of study. Data will be collected on a pre-designed structured proforma. Demographic data including age, gender, educational status, socioeconomic status will be noted. Each participant will undergo a complete history assessment and the OSDI score will be calculated after taking extensive history. Ophthalmologic examination, including visual acuity, refraction, slit-lamp examination, corneal staining, schirmer test and TBUT will be performed in each patient. Both eyes will be selected for each secondary outcome measure (TBUT & SCHIRMER TEST). However, only one OSDI score could only be obtained per patient for assessing primary outcome. All the previous medications used for dry eye will be stopped Participants' eyes will be randomized by blocked randomization in a 1:1 ratio to be treated with topical artificial tears (group I) and topical insulin 1U/ml (group II). The patients will be masked for the treatment, but not the principle investigator. Another investigator will prepare the topical insulin according to a written protocol. Participants will be given a white, unlabeled eye dropper containing the same volume of artificial tears or topical insulin for groups I and II respectively. Group I will receive artificial tears (control group) four times daily. Group II will receive topical insulin of 1u/ml four times daily. Follow-up assessments will be conducted at 4, 8 and 12 weeks for each participant to measure changes in TBUT, schirmer test, and OSDI score.

Inclusion Criteria:

• Patients having Schirmer's test values of less than 10mm after 5 minutes of the procedure recording plus a non-invasive tear breakup time (TBUT) of less than 10 seconds and the Ocular Surface Disease Index (OSDI) of more than 32 (diagnosed as dry eye disease as per the operational definition of this study).
• any gender.
• aged 18 years and above.

Exclusion Criteria:

• Patients with active ocular infection, severe ocular surface disease other than Dry eye disease, and those who have undergone ocular surgery within the past 6 months.
• Under 18 years old

The patients will be masked for the treatment, but not the principle investigator. Another investigator will prepare the topical insulin according to a written protocol. Participants will be given a white, unlabeled eye dropper containing the same volume of artificial tears or topical insulin for groups I and II respectively.