Diabetes mellitus (DM), prediabetes, and obesity are emerging as major global public health problems, with their epidemic spread continuously increasing over the past decades. The occurrence of diabetic retinopathy, cataract, glaucoma, and ocular surface disease in patients with diabetes mellitus has been extensively investigated in several studies. However, mild ocular surface disorders, such as dry eye disease, have often been overlooked, with a previous study showing that 51.3% of diabetes-related dry eye disease cases remained underdiagnosed. Among systemic diseases, diabetes mellitus and obesity have been associated with an increased risk of developing dry eye disease. Chronic hyperglycemia in diabetes leads to microvascular damage, including corneal neuropathy and reduced tear production, conditions that can disrupt ocular surface health, while systemic inflammation and meibomian gland dysfunction also contribute to this process. However, the effect of newer classes of antidiabetic medications, including glucagon-like peptide-1 receptor agonists (GLP-1 RAs), on ocular surface health remains insufficiently understood. The aim of this prospective cohort study is to evaluate the effects of GLP-1 receptor agonists on dry eye disease in patients with type 2 diabetes mellitus and obesity through the assessment of ocular surface parameters, such as tear film break-up time, Schirmer test results, as well as potential changes in corneal topography.

This prospective cohort study aims to shed a light to the effects of GLP-1 RAs on Dry Eye Disease in Patients with Type 2 Diabetes Mellitus and Obesity.

Inclusion Criteria:

1. Age ≥18 years.
2. Patients who have not previously received GLP-1 receptor agonists (GLP-1 RAs).
3. Patients able to provide informed consent for participation in the study.

Exclusion Criteria:

1. Pregnant or breastfeeding patients.
2. History of multiple severe hypoglycemic episodes within the past two years.
3. Active intraocular inflammation in either eye, such as infectious conjunctivitis, keratitis, scleritis, endophthalmitis, or autoimmune uveitis.
4. Patients who have undergone cataract surgery or vitrectomy within the past 6 months.
5. History of ketoacidosis or metabolic acidosis.
6. History of corneal transplantation.

The diagnosis of diabetes mellitus will be established according to the diagnostic criteria defined by the European Association for the Study of Diabetes (EASD), the American Diabetes Association (ADA), and the European Association for the Study of Obesity (EASO).

Male and/or female patients attending the regular outpatient ophthalmology clinics, with stable refraction over the past two years, without pathological corneal findings (including corneal ulcer, keratoconus, corneal dystrophies, corneal trauma/abrasions), no history of corneal infections during the last 2 years, and no history of refractive surgery will be included.

To ensure the objectivity of the results, the assessment of dry eye disease parameters will be performed by an ophthalmologist blinded to the patient's study group allocation (single-blinded design), thereby minimizing the possibility of observer bias during data collection.